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EDUCATION

WORK AND ADULT LIFE

A number of other disorders may include characteristics of autism. In fragile X syndrome, which results from a defective X chromosome, people may show poor eye contact, limited speech, hand flapping, and hyperactivity. People with Asperger’s disorder may show some symptoms of autism such as difficulties in social interactions, poor eye contact, repetitive body movements, and an insistence on routines and rituals. However, they have normal language development and do not have mental retardation. Rett’s disorder involves repetitive hand movements, social withdrawal, and impaired language development. The disorder appears before the age of four and affects only girls. Some experts regard these disorders as mild forms of autism rather than as separate disorders.



Contributed By:
Michael Woods





WORK AND ADULT LIFE

Autism
CHARACTERISTICS
CAUSES
TREATMENT

EDUCATION

WORK AND ADULT LIFE

Some individuals with autism get jobs and live independently or semi-independently as adults. They often succeed in jobs that emphasize specific skills, rather than those that require complex interactions with other people. Others with autism must depend on outside support. They may live with family members, in group homes, or in residential care facilities.

RELATED DISORDERS



Contributed By:
Michael Woods


EDUCATION Autism

EDUCATION

Federal law in the United States requires that states provide early intervention services for children aged one to three with autism and other disabilities. These services try to help children with autism develop academic and social skills in the hopes of lessening the disorder’s long-term effects. States also must provide an individual education plan when these children begin school. Children with autism may attend regular or special schools. See also Education of Students with Mental Retardation; Special Education.

WORK AND ADULT LIFE



Contributed By:
Michael Woods


TREATMENT

Autism

CHARACTERISTICS


CAUSES

TREATMENT

here is no cure for autism. But treatment may reduce symptoms and help people with autism function better. Experts disagree over the effectiveness of different treatments. Many treatments seemed promising when first introduced, but later proved disappointing. Because individuals respond in different ways, no single treatment works for everyone. Treatments include behavior modification, medication, facilitated communication, vitamin and mineral supplements, auditory training, and vision therapy.

Behavior modification involves analyzing the cause of an undesirable behavior, then using rewards and punishments or other approaches to replace the behavior with a more appropriate response. For instance, children who spin or flap their arms because of anxiety about a situation can be taught to say “stop” or point to a symbol for “stop.” Parents often collaborate with therapists in providing behavior therapy. Very intensive behavior programs, modeled on the teaching methods of American psychologist O. Ivar Lovaas, have yielded some of the best results. In such programs parents may provide therapy at home seven days a week for several years.

Physicians sometimes prescribe antipsychotic drugs, beta-blockers, anticonvulsants, and other medications to reduce self-abusive behavior, such as head banging and wrist biting. Some individuals with autism benefit from drugs that increase levels of serotonin, a brain chemical. These medications, which include fenfluramine (Pondimin), fluvoxamine (Luvox), and clomipramine (Anafranil), may reduce compulsive behavior and body movements. Other drugs that improve symptoms in some patients include naltrexone (ReVia), which blocks the action of natural opiate-like compounds in the brain, and haloperidol (Haldol), which interferes with the function of the neurotransmitter dopamine.

Facilitated communication is based on the idea that people with autism are unable to communicate because of impaired body coordination. In this technique, a trained professional, or facilitator, supports the person’s hand over an alphanumeric keyboard. The person with autism learns to type messages and responses to questions. Critics maintain that the facilitator, rather than the person with autism, is the true source of the messages.

Other treatments for autism include supplements of vitamin B6 and magnesium; auditory training for individuals who are hypersensitive to certain frequencies of sound; and vision training to correct eyesight problems.


EDUCATION

WORK AND ADULT LIFE

RELATED DISORDERS


Contributed By:
Michael Woods


CAUSES

Autism
CHARACTERISTICS

CAUSES

Scientists once regarded autism as a psychological disorder caused by traumatic experiences that forced a child to retreat into a world of fantasy. Some theorized that parents caused autism by unconsciously rejecting a child, or by failing to bond emotionally. These theories caused enormous guilt in parents and lacked any scientific validity. Scientists today still do not know what causes autism, but they have discredited and rejected theories about a parental cause.

Evidence indicates that autism results from biological abnormalities in brain structure and function. Studies have found that autistic people have abnormally low blood flow to certain parts of the brain and reduced numbers of certain brain cells. These studies suggest that mutations in genes are important in causing autism. Studies of families also support this possibility. For example, families with one autistic child are more likely to have a second autistic child. Other studies have linked some cases of autism with prenatal exposure to the rubella virus (see German Measles) and lack of oxygen during birth.

Another theory sees autism mainly as a problem of cognition. In this view, autism results from an inability to think in ways necessary for normal communication, sharing of experiences, and expression of emotions. Supporters argue that autistic people lack “a theory of the mind”—that is, they do not realize that other people have feelings, beliefs, needs, and an inner life. Without this conception of the minds of others, autistic people cannot predict or interpret the behavior of others and have severe problems in social interaction. Many experts criticize this theory, noting that autism appears at an early age when no children have a conception of the minds of others.
TREATMENT

EDUCATION

WORK AND ADULT LIFE

RELATED DISORDERS



Contributed By:
Michael Woods


CHARACTERISTICS Autism

CHARACTERISTICS

Autism is often referred to as a spectrum disorder—that is, a disorder in which symptoms can occur in any combination and with varying degrees of severity. Symptoms of autism usually begin during infancy. Autistic infants may stiffen or go limp when picked up by parents rather than clinging or cuddling up to them. Autistic infants often show little or no interest in other people and lack typical social behaviors. For example, they may not smile at their mother’s voice or make eye contact with caregivers. Autistic children fail to develop normal relationships with their parents, brothers or sisters, and other children. Often they seem unaware of the needs and feelings of other people, and may not respond if another person is hurt or in distress. They also fail to make friends.

Children with autism usually play alone. Often they engage in repetitious activities, such as arranging objects in meaningless patterns, flipping a light switch on and off, or staring at rotating objects. Some engage in repetitious body movements, such as spinning, flapping their arms, swaying, rocking, snapping their fingers, and clapping or flapping their hands. In some cases these movements may be harmful, involving repeated biting of their wrists or banging their head. Children with autism frequently become upset at minor changes in their surroundings and daily routines.

Autistic children also have difficulties with language. Some never learn to speak or develop very limited speech. An autistic child may say “you” when he means “I” and produce incorrectly formed sentences. For example, when the child wants a drink he may say, “You want a drink.” Autistic children may also demonstrate echolalia, mechanically repeating words or phrases that other people say.

About 75 percent of autistic children are classified as having mental retardation, meaning that they score well below average on a standard test of intelligence and that they have a significantly impaired ability to cope with common life demands. Many show great variability in their skill levels across different aspects of intelligence tests, characteristically scoring higher on tests of visual-spatial skills and rote memory than on tests of verbal skills and social understanding. Some experts argue that standard intelligence tests are inappropriate measures of an autistic person's intellectual abilities. These experts note that some symptoms of autism—such as speech and language problems, difficulty paying attention, and behavioral problems—may interfere with an autistic child's performance on standard intelligence tests.

Children and adults with autism who score in the average or high range on intelligence tests are considered to have high-functioning autism. About 10 percent of autistic individuals have extraordinary talents such as the ability to memorize long lists of information, the ability to make lightning-fast mathematical calculations, or precocious musical or artistic abilities. Experts call such individuals autistic savants. Savants may score above or below average on standard intelligence tests.

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TREATMENT

EDUCATION

WORK AND ADULT LIFE

RELATED DISORDERS



Contributed By:
Michael Woods


Autism

Autism



Therapist and Autistic Child

A therapist works with an autistic boy in a public school. Autism severely impairs a child’s ability to learn, communicate, and interact with others. Behavior modification and other forms of treatment can improve the language and social skills of children with autism.

Autism, disorder that severely impairs development of a person’s ability to communicate, interact with other people, and maintain normal contact with the outside world. The disorder was first described in 1943 by American psychiatrist Leo Kanner. One of the most common developmental disabilities, autism affects approximately 1 in 500 to 1 in 166 children and appears before the age of three. It is about four times more common in males than in females.

CHARACTERISTICS
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EDUCATION

WORK AND ADULT LIFE

RELATED DISORDERS



Contributed By:
Michael Woods


Computer Science

Computer Science, study of the theory, experimentation, and engineering that form the basis for the design and use of computers—devices that automatically process information. Computer science traces its roots to work done by English mathematician Charles Babbage, who first proposed a programmable mechanical calculator in 1837. Until the advent of electronic digital computers in the 1940s, computer science was not generally distinguished as being separate from mathematics and engineering. Since then it has sprouted numerous branches of research that are unique to the discipline.

II.THE DEVELOPMENT OF COMPUTER SCIENCE WORLD OF SCIENCE

Dr. Atanasoff's ComputerAmerican physicist John Atanasoff built the first rudimentary electronic computer in the late 1930s and early 1940s, although for several decades afterward credit for the first electronic computer went to the scientists who assembled the Electronic Numerical Integrator and Computer (ENIAC) for the United States military by 1945. Danish physicist Allan Mackintosh recounts in a Scientific American article how Atanasoff first conceived of the design principles that are still used in present-day computers. Open sidebarEarly work in the field of computer science during the late 1940s and early 1950s focused on automating the process of making calculations for use in science and engineering. Scientists and engineers developed theoretical models of computation that enabled them to analyze how efficient different approaches were in performing various calculations. Computer science overlapped considerably during this time with the branch of mathematics known as numerical analysis, which examines the accuracy and precision of calculations. (see ENIAC, UNIVAC.)As the use of computers expanded between the 1950s and the 1970s, the focus of computer science broadened to include simplifying the use of computers through programming languages—artificial languages used to program computers, and operating systems—computer programs that provide a useful interface between a computer and a user. During this time, computer scientists were also experimenting with new applications and computer designs, creating the first computer networks, and exploring relationships between computation and thought.In the 1970s, computer chip manufacturers began to mass produce microprocessors—the electronic circuitry that serves as the main information processing center in a computer. This new technology revolutionized the computer industry by dramatically reducing the cost of building computers and greatly increasing their processing speed. The microprocessor made possible the advent of the personal computer, which resulted in an explosion in the use of computer applications. Between the early 1970s and 1980s, computer science rapidly expanded in an effort to develop new applications for personal computers and to drive the technological advances in the computing industry. Much of the earlier research that had been done began to reach the public through personal computers, which derived most of their early software from existing concepts and systems.Computer scientists continue to expand the frontiers of computer and information systems by pioneering the designs of more complex, reliable, and powerful computers; enabling networks of computers to efficiently exchange vast amounts of information; and seeking ways to make computers behave intelligently. As computers become an increasingly integral part of modern society, computer scientists strive to solve new problems and invent better methods of solving current problems.The goals of computer science range from finding ways to better educate people in the use of existing computers to highly speculative research into technologies and approaches that may not be viable for decades. Underlying all of these specific goals is the desire to better the human condition today and in the future through the improved use of information.

III.THEORY AND EXPERIMENT

Computer science is a combination of theory, engineering, and experimentation. In some cases, a computer scientist develops a theory, then engineers a combination of computer hardware and software based on that theory, and experimentally tests it. An example of such a theory-driven approach is the development of new software engineering tools that are then evaluated in actual use. In other cases, experimentation may result in new theory, such as the discovery that an artificial neural network exhibits behavior similar to neurons in the brain, leading to a new theory in neurophysiology.It might seem that the predictable nature of computers makes experimentation unnecessary because the outcome of experiments should be known in advance. But when computer systems and their interactions with the natural world become sufficiently complex, unforeseen behaviors can result. Experimentation and the traditional scientific method are thus key parts of computer science.

IV.MAJOR BRANCHES OF COMPUTER SCIENCE

Computer science can be divided into four main fields: software development, computer architecture (hardware), human-computer interfacing (the design of the most efficient ways for humans to use computers), and artificial intelligence (the attempt to make computers behave intelligently). Software development is concerned with creating computer programs that perform efficiently. Computer architecture is concerned with developing optimal hardware for specific computational needs. The areas of artificial intelligence (AI) and human-computer interfacing often involve the development of both software and hardware to solve specific problems.

A.Software DevelopmentIn developing computer software, computer scientists and engineers study various areas and techniques of software design, such as the best types of programming languages and algorithms (see below) to use in specific programs, how to efficiently store and retrieve information, and the computational limits of certain software-computer combinations. Software designers must consider many factors when developing a program. Often, program performance in one area must be sacrificed for the sake of the general performance of the software. For instance, since computers have only a limited amount of memory, software designers must limit the number of features they include in a program so that it will not require more memory than the system it is designed for can supply.Software engineering is an area of software development in which computer scientists and engineers study methods and tools that facilitate the efficient development of correct, reliable, and robust computer programs. Research in this branch of computer science considers all the phases of the software life cycle, which begins with a formal problem specification, and progresses to the design of a solution, its implementation as a program, testing of the program, and program maintenance. Software engineers develop software tools and collections of tools called programming environments to improve the development process. For example, tools can help to manage the many components of a large program that is being written by a team of programmers.Algorithms and data structures are the building blocks of computer programs. An algorithm is a precise step-by-step procedure for solving a problem within a finite time and using a finite amount of memory. Common algorithms include searching a collection of data, sorting data, and numerical operations such as matrix multiplication. Data structures are patterns for organizing information, and often represent relationships between data values. Some common data structures are called lists, arrays, records, stacks, queues, and trees.Computer scientists continue to develop new algorithms and data structures to solve new problems and improve the efficiency of existing programs. One area of theoretical research is called algorithmic complexity. Computer scientists in this field seek to develop techniques for determining the inherent efficiency of algorithms with respect to one another. Another area of theoretical research called computability theory seeks to identify the inherent limits of computation.Software engineers use programming languages to communicate algorithms to a computer. Natural languages such as English are ambiguous—meaning that their grammatical structure and vocabulary can be interpreted in multiple ways—so they are not suited for programming. Instead, simple and unambiguous artificial languages are used. Computer scientists study ways of making programming languages more expressive, thereby simplifying programming and reducing errors. A program written in a programming language must be translated into machine language (the actual instructions that the computer follows). Computer scientists also develop better translation algorithms that produce more efficient machine language programs.Databases and information retrieval are related fields of research. A database is an organized collection of information stored in a computer, such as a company’s customer account data. Computer scientists attempt to make it easier for users to access databases, prevent access by unauthorized users, and improve access speed. They are also interested in developing techniques to compress the data, so that more can be stored in the same amount of memory. Databases are sometimes distributed over multiple computers that update the data simultaneously, which can lead to inconsistency in the stored information. To address this problem, computer scientists also study ways of preventing inconsistency without reducing access speed.Information retrieval is concerned with locating data in collections that are not clearly organized, such as a file of newspaper articles. Computer scientists develop algorithms for creating indexes of the data. Once the information is indexed, techniques developed for databases can be used to organize it. Data mining is a closely related field in which a large body of information is analyzed to identify patterns. For example, mining the sales records from a grocery store could identify shopping patterns to help guide the store in stocking its shelves more effectively. (see Information Storage and Retrieval.)Operating systems are programs that control the overall functioning of a computer. They provide the user interface, place programs into the computer’s memory and cause it to execute them, control the computer’s input and output devices, manage the computer’s resources such as its disk space, protect the computer from unauthorized use, and keep stored data secure. Computer scientists are interested in making operating systems easier to use, more secure, and more efficient by developing new user interface designs, designing new mechanisms that allow data to be shared while preventing access to sensitive data, and developing algorithms that make more effective use of the computer’s time and memory.The study of numerical computation involves the development of algorithms for calculations, often on large sets of data or with high precision. Because many of these computations may take days or months to execute, computer scientists are interested in making the calculations as efficient as possible. They also explore ways to increase the numerical precision of computations, which can have such effects as improving the accuracy of a weather forecast. The goals of improving efficiency and precision often conflict, with greater efficiency being obtained at the cost of precision and vice versa.Symbolic computation involves programs that manipulate nonnumeric symbols, such as characters, words, drawings, algebraic expressions, encrypted data (data coded to prevent unauthorized access), and the parts of data structures that represent relationships between values (see Encryption). One unifying property of symbolic programs is that they often lack the regular patterns of processing found in many numerical computations. Such irregularities present computer scientists with special challenges in creating theoretical models of a program’s efficiency, in translating it into an efficient machine language program, and in specifying and testing its correct behavior.

B.Computer ArchitectureComputer architecture is the design and analysis of new computer systems. Computer architects study ways of improving computers by increasing their speed, storage capacity, and reliability, and by reducing their cost and power consumption. Computer architects develop both software and hardware models to analyze the performance of existing and proposed computer designs, then use this analysis to guide development of new computers. They are often involved with the engineering of a new computer because the accuracy of their models depends on the design of the computer’s circuitry. Many computer architects are interested in developing computers that are specialized for particular applications such as image processing, signal processing, or the control of mechanical systems. The optimization of computer architecture to specific tasks often yields higher performance, lower cost, or both.

C.Artificial IntelligenceArtificial intelligence (AI) research seeks to enable computers and machines to mimic human intelligence and sensory processing ability, and models human behavior with computers to improve our understanding of intelligence. The many branches of AI research include machine learning, inference, cognition, knowledge representation, problem solving, case-based reasoning, natural language understanding, speech recognition, computer vision, and artificial neural networks.A key technique developed in the study of artificial intelligence is to specify a problem as a set of states, some of which are solutions, and then search for solution states. For example, in chess, each move creates a new state. If a computer searched the states resulting from all possible sequences of moves, it could identify those that win the game. However, the number of states associated with many problems (such as the possible number of moves needed to win a chess game) is so vast that exhaustively searching them is impractical. The search process can be improved through the use of heuristics—rules that are specific to a given problem and can therefore help guide the search. For example, a chess heuristic might indicate that when a move results in checkmate, there is no point in examining alternate moves.

D.RoboticsAnother area of computer science that has found wide practical use is robotics—the design and development of computer controlled mechanical devices. Robots range in complexity from toys to automated factory assembly lines, and relieve humans from tedious, repetitive, or dangerous tasks. Robots are also employed where requirements of speed, precision, consistency, or cleanliness exceed what humans can accomplish. Roboticists—scientists involved in the field of robotics—study the many aspects of controlling robots. These aspects include modeling the robot’s physical properties, modeling its environment, planning its actions, directing its mechanisms efficiently, using sensors to provide feedback to the controlling program, and ensuring the safety of its behavior. They also study ways of simplifying the creation of control programs. One area of research seeks to provide robots with more of the dexterity and adaptability of humans, and is closely associated with AI.

E.Human-Computer InterfacingHuman-computer interfaces provide the means for people to use computers. An example of a human-computer interface is the keyboard, which lets humans enter commands into a computer and enter text into a specific application. The diversity of research into human-computer interfacing corresponds to the diversity of computer users and applications. However, a unifying theme is the development of better interfaces and experimental evaluation of their effectiveness. Examples include improving computer access for people with disabilities, simplifying program use, developing three-dimensional input and output devices for virtual reality, improving handwriting and speech recognition, and developing heads-up displays for aircraft instruments in which critical information such as speed, altitude, and heading are displayed on a screen in front of the pilot’s window. One area of research, called visualization, is concerned with graphically presenting large amounts of data so that people can comprehend its key properties.


V.CONNECTION OF COMPUTER SCIENCE TO OTHER

DISCIPLINES Because computer science grew out of mathematics and , it retains many close connections to those disciplines. Theoretical computer science draws many of its approaches from mathematics and logic. Research in numerical computation overlaps with mathematics research in numerical analysis. Computer architects work closely with the electrical engineers who design the circuits of a computer.Beyond these historical connections, there are strong ties between AI research and psychology, neurophysiology, and linguistics. Human-computer interface research also has connections with psychology. Roboticists work with both mechanical engineers and physiologists in designing new robots.Computer science also has indirect relationships with virtually all disciplines that use computers. Applications developed in other fields often involve collaboration with computer scientists, who contribute their knowledge of algorithms, data structures, software engineering, and existing technology. In return, the computer scientists have the opportunity to observe novel applications of computers, from which they gain a deeper insight into their use. These relationships make computer science a highly interdisciplinary field of study.
Contributed By:Charles C. Weems

PREVENTION

PREVENTION
Scientists estimate that more than 60 percent of cancer deaths in the United States are preventable through lifestyle changes. Although there is no certain way to avoid all cancers, reducing individual risk factors significantly decreases the likelihood of contracting many forms of this devastating disease.

Lifestyle Changes

The ACS estimates that smoking causes nearly 30 percent of all cancer deaths in the United States—that is, approximately 166,000 cancer deaths each year. All cancer deaths caused by tobacco smoking could be prevented completely by not smoking and not using smokeless tobacco. For those who already smoke, quitting will reduce the risk of developing cancer. Studies show that after about ten years of not smoking, a past smoker’s risk lowers to about the level of those who have never smoked.
After quitting smoking, eating a healthy diet is the best way to lower the risk of cancer. Certain foods have been found to protect against cancer. Among these foods are broccoli, cauliflower, cabbage, tomatoes, soy products, and foods high in vitamins A, C, and E. In addition, green and possibly black teas contain compounds that protect the body from carcinogens. These foods contain substances called antioxidants that block the action of free radicals. Other chemicals in fruits and vegetables are thought to block the cell growth promoting effects of steroid hormones, protecting against cancers of the breast and prostate.
To lower cancer risk, diets should include little or no red meat. Other foods to avoid or consume in moderation include sugar, saturated fat from animal products, and salt. Added fats and oils should come from vegetables, such as olives or corn, rather than from animal sources. Carbohydrates should come from whole grains, such as brown rice and whole wheat bread, rather than from processed foods, such as white rice and white bread.
The risk of cancer of the esophagus increases with heavy alcohol consumption, and many studies suggest that consuming alcoholic beverages increases the risk of breast cancer as well. Studies show that limiting intake to two drinks a day for men, and one drink per day for women, reduces cancer risk.
Low levels of physical activity have been implicated in colon cancer. Moderate activity for 30 minutes a day enhances the immune system, shortens the time food takes to move through the intestines, and alters body composition and hormone levels. Researchers are studying how these effects might lower cancer risk. Physical activity also helps avoid obesity, which is associated with an increased risk for cancers of the colon and rectum, prostate, breast, endometrium, and kidney. By maintaining a healthy weight through regular physical activity and a healthy diet, individuals can substantially lower their risk for these cancers.
Protecting the skin from the sun’s rays could prevent about 80 percent of all skin cancers. When in the sun for prolonged periods, always wear sunscreen with a sun protection factor (SPF) of 15 or greater, particularly if you have fair skin or freckles. Skin needs protection every day, not just on sunny days. The Skin Cancer Foundation also recommends that people avoid the sun at its peak (from 10 am to 4 pm), seek shade, and cover up with clothing and a brimmed hat.
People also can help prevent cancer by practicing safe sex or abstaining from sex. The human papilloma virus (HPV) linked to cervical cancer is the most common cancer-causing virus in the United States. Minimizing the number of sexual partners, using condoms, or practicing sexual abstinence reduces risk of infection with HPV. Infection with the human immunodeficiency virus (HIV), also sexually transmitted, greatly increases an individual’s risk for cancers of the immune and lymphatic system, such as Kaposi’s sarcoma. Infection with the hepatitis B virus (HBV) is the predominant cause of liver cancer in the United States. HBV is transmitted from person to person through unprotected sexual intercourse with an infected person, or through the sharing of infected needles or other sharp instruments that break the skin. Vaccination against hepatitis B reduces the spread of this virus, which leads to reduced incidence of liver cancer.



Screening and Early Detection
Double-Contrast Barium X Ray of the Large Intestine
Detecting cancer in its early stages significantly improves a patient’s chances for survival. The American Cancer Society recommends that symptom-free patients undergo a number of regular screening tests. One such test, a double-contrast barium enema, is used to detect colorectal cancer. Barium, an X-ray opaque material or contrast medium, makes intestinal tumors and other defects stand out as dark spots against the brighter healthy intestinal tissue in X rays. The American Cancer Society recommends people over age 50 have a double-contrast barium enema every 5 to 10 years.

The next best thing to lifestyle changes is early detection to prevent cancer from becoming life threatening. Detecting a tumor while it is still in an early stage is the best predictor of long-term survival. For this reason, the ACS recommends a number of screening tests for people who do not have symptoms. A cancer-related checkup is recommended every three years for people aged 20 to 40 and every year for people over age 40. For more information about other screening tests, see the table on Cancer Screening Recommendations.
In addition to regular cancer check ups, advanced technologies may help detect certain cancers. Scientists have developed tests for the presence of certain genetic mutations. People who test positive for these genetic mutations may take preventive measures such as more frequent cancer screening examinations and dietary modification to reduce their risk. Women who test positive for a mutated breast cancer gene, such as BRCA1 or BRCA2, may choose to have a mastectomy even when no cancer is present. This eliminates most breast tissue before cancer has a chance to form.
The ability to determine a person's genetic risk for cancer years or even decades before it develops has raised a number of ethical, social, and psychological implications. Several government committees have published guidelines to prevent discrimination in hiring or firing employees who have had a genetic test or have tested positive for a particular cancer-causing gene. Families with high risk for cancer are also affected by the psychological implications of knowing which family members are at risk and which are not. In some cases, tests are available to identify people at risk for certain cancers, such as inherited forms of breast or colon cancers, but surefire preventive or treatment measures for these cancers have not been developed yet. While some people would prefer to know their risk for disease so they can make appropriate lifestyle changes, others prefer not to be hampered by this knowledge when no treatment exists for the problem.
CANCER RESEARCH
Sixty percent of people diagnosed with cancer now survive more than five years. Between 1990 and 1995 cancer incidence and death rates dropped for the first time in 20 years. In 1998 the ACS, the NCI, and the Centers for Disease Control and Prevention (CDC) confirmed that cancer rates are still on the decline. In the past 40 years, the death rate from cancer in children has dropped 62 percent. These improved cancer statistics are due in part to behavioral and lifestyle changes, but equal credit goes to the advances in cancer research that have taken place in the last three decades.

Clinical Trials

Clinical trials are research studies that use human patients to determine if a new treatment is effective. Medical and ethical panels overseen by the Food and Drug Administration (FDA) carefully review the research methods and ethics of a clinical trial before the trial begins, then monitor the trial throughout its four main phases. Phase I of a clinical trial studies a small number of patients to determine the best dosage and delivery method of a new drug treatment. Patients who participate in a Phase I trial usually have advanced cancer and would not be helped by other known treatments. Phase II, conducted with a different group of patients, determines how well the treatment actually works in different types of cancer. Phase III compares the effectiveness of the new treatment in one set of patients to another set of patients who receive the best currently available drug treatment. In Phase IV studies, the treatment becomes part of the standard treatment regimen, but it is tested for how effective it is when combined with other treatments.
Researchers continually study and find new ways to treat cancer. Studies in an area of research called antimetastasis focus on halting tumor cells from spreading and invading new tissues. Other researchers study how to stop a tumor from developing its own blood supply, a process called antiangiogenesis. Two antiangiogenesis drugs, called angiostatin and endostatin, stop the growth of blood vessels and have been quite successful in treating tumors in mice. These two drugs are currently in clinical trials in humans.
Several drugs that block oncogene signals are in clinical trials. Researchers are also introducing genes into immune cells that will specifically recognize and kill cancer cells. Other research is investigating the introduction of a normal gene into a tumor cell to increase the tumor's sensitivity to chemotherapeutic drugs.
A growing field of cancer prevention research is chemoprevention, or the use of natural or synthetic compounds to decrease the number of mutations that may lead to cancer. Chemoprevention research seeks to identify those compounds that reduce risk and use them in pills or food additives as a prevention measure for those who are at high risk for cancer. More than two dozen chemopreventive compounds are currently being studied for how well they work in humans.

Basic Research


Scientists who conduct basic research on the causes of cancer focus on the fundamental genetic mutations that underlie cancer. One goal seeks to identify all of the mutations present in a patient’s tumor, enabling better prediction of the tumor’s future behavior. Developing technologies use a tiny glass chip the size of a computer chip to compare DNA in tumor cells to DNA in healthy cells. This new diagnostic tool will someday help physicians to tailor the treatment of individual patients according to their tumors’ genetic makeup.
Since cancer is uncontrolled cell division, research into the genetic mechanisms that control normal cell division also holds promise. A better understanding of the normal function of a mutated gene may provide better insight into what goes wrong in tumor cells. This may lead to better treatments designed to combat specifically the effects of the mutation.
Contributed By:Karen R. Peterson

Immunotherapy

Immunotherapy



Producing Monoclonal Antibodies
In the creation of a monoclonal antibody, a normal B cell (a type of lymphocyte, or white blood cell) is united with a myeloma cell (a type of cancer). This union results in the formation of hybridomas (hybrid cells) that have the cancer cell’s trait of dividing endlessly and the B cell’s ability to produce a specific type of antibody. Monoclonal antibodies are designed to target specific molecules in the body. They have a variety of uses from pregnancy testing to treating certain cancers.

Immunotherapy, also called biologic therapy, uses the body’s own immune system to fight cancer cells or protect the body from side effects. Immunotherapy relies on antibodies, naturally occurring proteins dedicated to defending the body against invasion by foreign substances. In one kind of immunotherapy, antibodies are used to attack tumor cells directly, while in another approach, antibodies are used to deliver toxic agents, such as radioactive substances or drugs, that selectively target and harm cancer cells. Monoclonal antibodies are laboratory-produced antibodies used to fight many diseases, including cancer. One of the newest treatments for breast cancer is a monoclonal antibody called Herceptin, which targets cancer cells that overproduce HER-2, the protein implicated in about one-third of all breast cancers.

Other forms of immunotherapy include the use of interferon, a naturally and synthetically produced protein that fights disease-causing agents in the body, particularly viruses. Interferons slow the growth of tumor cells in some patients, and they stimulate the immune system to attack cancerous cells. Another therapy, interleukin-2, is a naturally occurring immune system chemical that stimulates a type of immune cell that attacks cancer cells. Colony stimulating factors help regulate the production of white blood cells, enabling the body to better combat the disease.

Contributed By:Karen R. Peterson


TREATMENT CANCER



TREATMENT
Oncologists select from a number of options when treating cancer, depending on the type and stage of the tumor involved. The major treatments currently available are surgery, radiation therapy, chemotherapy, hormone therapy, and immunotherapy. Often, targeting cancerous tumors requires the artful combination of more than one type of cancer therapy.


Surgery

Surgery is the most effective and fastest treatment for tumors that are caught early and have not metastasized. It is the only option ensuring that the entire visible tumor is eliminated. However, there is no guarantee that all microscopic extensions of a tumor have been removed. For this reason, surgeons may also remove a large portion of healthy tissue that surrounds the tumor. This may not be possible if the tumor lies near or within a vital tissue, such as a major nerve or organ.

Often, cancer surgery requires general anesthesia, in which the patient loses consciousness, and a hospital stay of several days. For example, women with breast cancer may have a lumpectomy or mastectomy, surgical removal of part (or all) of the breast. Depending on the stage of the tumor, doctors may also remove the nearby lymph nodes and muscle tissue. As with any major surgery, mastectomies and other major surgical cancer treatments involve some risk, and doctors must consider the overall health of the patient, as well as the stage of the tumor.
Some cancers can be treated surgically with less-invasive techniques, such as laser surgery. Laser surgery uses a powerful beam of high-energy light to vaporize certain tumors of the cervix, larynx, and skin. Physicians perform laser surgery with an endoscope inserted through a small incision in the skin. Laser surgery and other less-invasive surgical procedures may require only local anesthesia, in which a patient loses feeling in one particular area of the body but never loses consciousness.

Sometimes oncologists recommend surgery to improve a patient’s quality of life, even if it is not likely to rid the body of cancer. Surgery of this type aims to correct a problem that is causing discomfort or disability. For example, some cancers may spread to the spine, pressing on the spinal cord or nearby nerves. This pressure may cause severe pain, and in some instances, paralysis. Surgical removal of all or part of the tumor near the spine may alleviate these symptoms.

Radiation Therapy

Radiation Treatment
Here, a patient undergoes radiation treatment for cancer of the spine. In this procedure the radioisotope cobalt 60 is used as the source of gamma radiation. A high dose of gamma radiation is guided by laser targeting to a localized area of treatment.
Therapeutic radiology uses high-energy particles or waves, such as X rays or gamma rays, to focus damaging radiation on the region of a tumor, inflicting genetic damage that kills cancerous cells. Radiation therapy damages rapidly dividing cells, mostly cancer cells but also healthy cells that reproduce quickly. This leads to side effects such as fatigue, skin changes, and loss of appetite. Other side effects usually are related to the treatment of specific areas, such as hair loss following radiation treatment to the head. Radiation therapy can also cause a decrease in the number of white blood cells, cells that help protect the body against infection. Most side effects are short-lived, as healthy tissues recover from radiation much better than cancer cells because healthy cells repair damaged DNA more efficiently.
Many short doses of radiation therapy, instead of fewer heavier doses, can minimize side effects. The total dose and the number of treatments depend on the size, location, and type of cancer and the patient’s general health. Patients usually receive radiation therapy five days a week for five to eight weeks. Weekend rest breaks allow normal cells to recover.

Unlike surgery, radiation can destroy microscopic cancer cells that have moved into surrounding tissues. Radiation is also a safer option for older patients or those weakened from other diseases, who may not recover well from surgery. Oncologists may use radiation to shrink the tumor, making surgery feasible. For other tumors, radiation may be used following surgery. However, radiation does not always eliminate all tumor cells, and it cannot treat widespread metastases. Like surgery, radiation therapy may be used to relieve pain and discomfort, even when a cure is not likely

Chemotherapy

Chemotherapy uses powerful anticancer drugs that travel through the bloodstream, making it potentially useful for cancers that have spread. Oncologists use about 50 different chemotherapeutic drugs to combat cancer, generally administering more than one drug at a time because these drugs are more powerful when combined. Taken orally or injected into the bloodstream, chemotherapeutic drugs interfere with cancer cells’ ability to make new DNA or divide properly. In some cases, the drugs cause programmed cell death. Many leukemias and lymphomas and cancer of the testicles are successfully treated with chemotherapy. Breast, lung, colorectal, and prostate cancer are not currently curable with chemotherapy alone, so chemotherapy is often used in combination with other therapies. In fact, the most common combination of cancer treatments is surgery or radiation therapy followed by chemotherapy.
Chemotherapy often causes severe side effects, particularly reduced resistance to infection, internal bleeding, diarrhea, nausea, vomiting, hair loss, and insufficient oxygen in the blood, known as anemia. Some tumors develop resistance to many drugs after exposure to just one drug, a condition called multidrug resistance. When this happens, there may be no drugs that are effective against the tumor.

Hormone Therapy

Some types of cancer, such as breast and prostate cancer, depend on sex hormones to grow. Hormone therapy prevents cancer cells from receiving or using the hormones they need. Hormone therapy may include surgery to remove organs in the endocrine system that make hormones. In other cases, hormone therapy relies on drugs to stop hormone production or change the way hormones work. Antiestrogen drugs, such as tamoxifen and raloxifene, given to women with breast cancer block estrogen and inhibit its ability to stimulate cell growth. Sometimes called designer estrogens, these drugs cause only mild side effects because treatment is limited to tissues affected by hormones. Androgen blockers are given to men with prostate cancer to block the production of testosterone and other male hormones that may contribute to cancer growth.
Contributed By:Karen R. Peterson

Staging

Staging

When a tumor is detected, the physician takes a biopsy by removing a sample of the tissue. The biopsy sample is inspected under a microscope to determine if the tumor is benign or malignant. Cancerous cells usually appear abnormal in shape and no longer orient themselves in orderly configurations. If the tumor is cancerous, the physician assigns it a stage, indicating how far cancer has spread. The stage is a key factor in determining both the cancer’s treatment and prognosis. Oncologists, physicians who specialize in the diagnosis and treatment of cancer, use several different staging systems. In one system, tumors are grouped into four stages denoted by Roman numerals I through IV. Stage I cancers are small localized cancers that are usually curable. Stage II and III tumors are usually locally advanced and may or may not have invaded nearby lymph nodes, and stage IV tumors have usually metastasized—that is, spread to distant tissues in the body.
The most widely used staging system is the Tumor, Lymph Node, and Metastasis system, commonly abbreviated TNM. This system uses numbers between zero and three to assess the size of the tumor (T), the extent that it has spread to nearby lymph nodes (N), and the extent that it has spread throughout the body (M). A cancer’s stage depends on a combination of these numbers. For example, a T-1, N-0, and M-0 tumor is a stage 1 tumor. This tumor is 2 cm (1 in) or less (T-1) and has not spread to nearby lymph nodes (accounting for N-0) or metastasized (M-0). The five-year survival rate for a patient with this stage tumor is accordingly excellent. A T-3, N-1, and M-0 tumor is a stage 3 tumor. This tumor is greater than 5 cm (2 in) and has spread to nearby lymph nodes, but there is no evidence that the cancer has spread to distant tissues. The five-year survival rate for a patient with this tumor is not as high as the T-1, N-0, M-0 patient. Stage 4 tumors are distinguished by an M-1 number. This means they have progressed to the point where metastasis is widespread, and the prognosis is usually quite poor.
Contributed By:Karen R. Peterson

DIAGNOSIS of CANCER

DIAGNOSIS
Diagnosis of cancer often begins when a person notices an unusual health symptom and consults a doctor. Early warning signs of cancer include changes in bowel or bladder habits, a sore that does not heal, unusual bleeding or discharge, thickening or a lump in the breast or any other part of the body, indigestion or difficulty swallowing, change in appearance of a wart or mole, or a nagging cough or hoarseness.


People with early warning signs should consult their family doctor, who will evaluate symptoms and may refer the patient to a physician who specializes in cancer. A physician will first take the patient’s medical history to learn about current symptoms, past history of disease, and family members diagnosed with cancer. The procedures used in a physical exam depend on the patient’s clinical symptoms and may include a digital rectal examination, in which the physician uses a gloved finger to gently check the smoothness of the rectal lining. The physician may perform a breast exam on female patients, in which the breasts are gently probed to feel for lumps or unusual masses.

During the examination the physician may use a thin, lighted tube called an endoscope to look for tumors in internal body cavities. The endoscopy procedure used depends on the organ or body cavity examined. In gastric endoscopy, the doctor feeds a specialized endoscope down the throat to examine the lining of the esophagus, stomach, and first part of the small intestine. Fiberoptic sigmoidoscopy, in which a flexible instrument is inserted into the lower intestinal tract through the anus, enables a physician to visually examine the interior of the colon and rectum. Colonoscopy uses a much longer flexible instrument to view the entire length of the large intestine.



Cervical Cells
Healthy cervical cells (left) are fairly uniform in size and shape, while diseased cervical cells (right) are irregular and disfigured. Gynecologists use a Pap smear to detect abnormalities in cervical cells, which may signal cancer. Cells are scraped from the cervix, and then are spread on slides and studied with a microscope.


A number of laboratory tests help narrow the possible diagnoses. In a Pap smear, cells are removed from the cervical epithelium with a small plastic brush. These cells are examined under a microscope for cell changes that are a sign that cancer may be developing as well as signs of malignancy. If a patient’s clinical signs suggest colorectal cancer, the doctor may search for blood in the stool using a fecal occult blood test. A small sample of the patient’s stool is smeared on a card coated with a chemical called guaiac, which reacts with blood. The card is analyzed in a laboratory for occult (hidden) blood. Certain blood tests determine if levels of red and white blood cells are low, a possible indication of leukemia. Others test for the presence of tumor markers, chemicals that are present in higher levels when certain cancers are present. For example, a prostate-specific antigen (PSA) test measures levels of prostate-specific antigen in the blood. Prostate cancer cells overproduce this protein, causing an elevation of PSA levels in blood.

Medical imaging techniques help doctors locate and evaluate a tumor. These include computed tomography (CT) and magnetic resonance imaging (MRI) scans. CT and MRI scans use computers to form a three-dimensional image of the tumor and surrounding tissues. X-ray images of the breast called mammograms help physicians detect and evaluate breast cancer. Ultrasound scanning bounces high-frequency sound waves off a tumor and surrounding tissue to create an image of the tumor. The multimodality display technique combines the images from several imaging tools into one picture, providing a final three-dimensional image with much greater detail. Computer-aided diagnosis uses complex computer programming technology called artificial intelligence to scan mammograms and X rays to help look for signs of cancer and offer an automated second opinion.



Type Stomach Cancer

Type Stomach Cancer

About 21,500 Americans and 2,800 Canadians are diagnosed with cancer of the stomach each year. Stomach cancer is about twice as common in men as it is in women, and it occurs much more frequently in people who have experienced long-term infection with the Helicobacter pylori bacterium. Incidence of stomach cancer varies significantly between different populations. In Japan, for example, the disease is five times more common than it is in the United States. Researchers attribute these regional risk differences to dietary differences. Diets high in smoked or cured meats appear to increase the risk of stomach cancer. In the United States, stomach cancer is now only one-fourth as common as it was in 1930. This decline may be due, in part, to the increased use of refrigeration for food storage and decreased use of salted and smoked foods.

Approximately 90 to 95 percent of all cancers of the stomach are adenocarcinomas that develop in the lining of the stomach. Cancers of the immune tissue in the stomach wall, called gastric lymphomas, make up about 4 percent of all cancers of the stomach. Gastric sarcomas develop in the muscle tissue in the stomach wall, and account for only about 3 percent of all stomach cancers.

Like many cancers of the internal organs, stomach cancer rarely produces noticeable symptoms until it has spread to other sites in the body. When symptoms are present, they may include abdominal pain, heartburn, nausea, and vomiting. Stomach cancer is rarely detected early, and only about 20 percent of people diagnosed with stomach cancer in the United States live five years or longer.

Contributed By:Karen R. Peterson

Type Ovarian Cancer

Type Ovarian Cancer

About 23,100 cases of ovarian cancer in American women and 2,500 cases in Canadian women are diagnosed annually. Women over the age of 50 have a higher risk for ovarian cancer, as do women who have had breast cancer. Other conditions that increase the risk for ovarian cancer include early age at first menstruation, late menopause, having a first child after age 30, or having no children at all. Women with a close relative who has ovarian cancer are also at greater risk, as are women with inherited mutations in the tumor suppressor genes BRCA1 and BRCA2.
The ovaries, two almond-shaped glands on either side of the uterus, produce eggs and release hormones that regulate menstruation and pregnancy. Malignant ovarian tumors arise in the epithelial tissue of the ovaries, in the connective tissue, or in the germ cells—the egg-producing cells. Ovarian carcinomas, those that arise in the epithelial tissue, account for 85 to 90 percent of all ovarian cancer. Sarcomas account for less than 5 percent of all cases, and several different types of germ cell cancers account for the remaining 5 to 10 percent of ovarian cancers.
Ovarian cancer accounts for just under 5 percent of all cancer in women. While rare, it often does not produce symptoms and goes undiagnosed until the cancer has spread and become more deadly. At that point, a woman may experience any of a variety of symptoms, such as an enlarged abdomen, persistent abdominal discomfort, indigestion, nausea or vomiting, weight loss, diarrhea or constipation, and bleeding that is not part of a normal menstrual period. If diagnosed and treated before the cancer has spread, the five-year survival rate in the United States is 95 percent, but only about 25 percent of ovarian cancers are detected this early. Overall, the five-year survival rate is 50 percent. Contributed By:Karen R. Peterson

Type Pancreatic Cancer

Type Pancreatic Cancer







Pancreas
Epidemiologists estimate that smoking causes 30 percent of all cases of pancreatic cancer, the fourth leading cause of cancer death in the United States. The pancreas has both a digestive and a hormonal function. Composed mainly of exocrine tissue, it secretes enzymes into the small intestine, where they help break down fats, carbohydrates, and proteins. Pockets of endocrine cells called the islets of Langerhans produce glucagon and insulin, hormones that regulate blood-sugar levels. About 95 percent of all pancreatic cancers begin in the exocrine tissue.

Each year about 28,300 Americans and 3,100 Canadians are diagnosed with cancer of the pancreas, a small gland sandwiched between the stomach and intestine that secretes chemicals used in digestion. Epidemiologists estimate that smoking causes about 30 percent of all cases of pancreatic cancer. Men are 30 percent more likely to develop this type of cancer than women, and in the United States, pancreatic cancer affects African Americans more than any other ethnic group.

The pancreas is composed of two different types of glands: exocrine and endocrine glands. Exocrine glands, which make up the bulk of the pancreas, produce enzymes that help the body break down fats and proteins. About 5 percent of the cells in the pancreas are endocrine glands. These cells secrete the hormones insulin and glucagon, which help control blood sugar levels. About 95 percent of all cancers that originate in the pancreas are adenocarcinomas of the exocrine glands. Cancers of the endocrine glands are very rare, and the following discussion pertains to cancer of the exocrine glands.

Although rarer than many types of cancer, pancreatic cancer is the fourth leading cause of cancer death in the United States because it produces few if any symptoms before it metastasizes. When symptoms are present, they may include jaundice, a yellowing of the skin, eyes, and fingernails; abdominal pain; weight loss; and digestive problems. Usually by the time symptoms appear, the cancer has spread to distant organs in the body. For this reason, only about 4 percent of all people diagnosed with pancreatic cancer in the United States survive five years or more.

Contributed By:Karen R. Peterson


Leukemia

Leukemia


Hairy Cell Leukemia
Pathologists can distinguish various types of leukemia by the appearance of the cancerous cells underneath a microscope. Hairy cell leukemia, a rare form of chronic lymphocytic leukemia, is characterized by cells with minute, hairlike projections on their surface.

Leukemia is cancer of the blood cells. About 31,000 new cases of leukemia are diagnosed in the United States and 3,500 new cases are diagnosed in Canada each year. Leukemia is typically thought to be a childhood disease, but in fact it strikes many more adults. Smoking increases the risk of developing leukemia, as does long-term exposure to high levels of the chemical benzene and high-dose radiation exposure.
There are four types of leukemia, classified by the type of blood cell affected and whether the cells are mature or immature. The four major types are acute myelocytic leukemia (AML), chronic myelocytic leukemia (CML), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL). AML and CLL are most common in adults, while ALL is the most common form in children. CML also affects adults. Acute leukemias progress rapidly, while chronic leukemias tend to develop slowly.

Most symptoms of leukemia result from the lack of normal blood cells that occurs when leukemia cells crowd out normal cells. General symptoms include weight loss, fever, and loss of appetite, and less often, profuse bleeding from the gums and mucous membranes under the skin. Low levels of red blood cells may also indicate the presence of leukemia.
In the United States the five-year survival rate varies according to the type of leukemia and the age of the patient. Almost 68 percent of the people diagnosed with CLL live at least five years. The five-year survival rate for adult ALL is almost 56 percent and is 70 percent for children with ALL. More than 27 percent of those diagnosed with CML survive five years or more. AML is the most fatal of the leukemias. The five-year survival rate for adults with this disease is just over 11 percent, while for children it is 40 percent.

Contributed By:Karen R. Peterson

 
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