Cancer : Articles

Cancer is the uncontrolled growth of abnormal cells in the body. Cancerous cells are also called malignant cells.

Cancer is not just one disease, but a large group of almost 100 diseases. It is a genetic disease, with two main characteristics of uncontrolled growth of the cells in the human body and the ability of those cells to migrate from the original site and spread to distant sites.

Cancer is the end product of a multistep process (carcinogenesis) that occurs over many years. The term "cancer" actually refers to numerous distinct diseases characterized by abnormal cell growth and differentiation. Cancers are categorized by the organ and/or cell of origin. For example, squamous cell carcinoma of the lung arises from pulmonary epithelial tissue, whereas adenocarcinoma of the breast arises from mammary duct epithelium. The natural history of a cancer is highly dependent on the organ and cell type from which it is derived. In addition, prognosis is influenced by the stage and histologic grade of the cancer. Staging is generally designated by the TNM (tumor, nodes, metastasis) staging system, which takes into account the size of the primary tumor(T), the extent to which local lymph nodes (glands) are involved (N), and whether or not distant metastases are present (M). The histologic grade, determined by microscopic examination of the biopsy specimen, provides an objective assessment of the degree of cellular differentiation.

A group of diseases characterized by uncontrollable cell growth. Cancer is a family of diseases in which cells replicate at an extremely rapid pace. A cancerous, or malignant, tumor begins its growth at a primary site, damaging surrounding tissue and interfering with normal organ function. Eventually, some of the cancerous cells may migrate from the primary tumor to other parts of the body-via the bloodstream and form secondary tumors. The specific causes of most forms of cancer are unknown, but researchers have uncovered many probable factors that contribute to the development of the disease, including certain chemicals and forms of radiation, cigarette smoking, diet, and, in some cases, genetic predisposition. Although most cancers occur in adults, cancer is still responsible for more deaths in children than any other disease in the United States, where it is the second leading cause of death—after accidents—in children under the age of 15. Between 7,000 and 8,000 new cases of childhood cancer are diagnosed in the U.S. every year. Like the cancer rate among the adult population, the incidence of cancer in children, especially acute lymphocytic leukemia and brain cancer, is on the rise. However, scientific advances in diagnosis and treatment have dramatically improved short- and long-term survival rates for many childhood cancers. Pediatrie oncologists specialize in the treatment of children with cancer. Childhood cancers are treated with the same three major techniques used for treating cancer in adults: chemotherapy, radiation, and surgery. In chemotherapy, medication is administered orally or intravenously to kill cancer cells, or to stop or retard their growth. Usually a combination of different drugs is used for maximum effectiveness. Chemotherapy agents are powerful drugs that cause unpleasant and sometimes serious side effects, including nausea, hair loss, mouth sores, bleeding, and decreased immune function. In radiation therapy, high doses of radiation are aimed at the affected area, killing cancer cells. This therapy brings many dangers to the patient. Radiation can kill cells or turn healthy cells into new cancer cells. Whole-body radiation, used to treat cancer that has spread, destroys the body's bone marrow. A matching donor, usually a close relative, must then be found to give marrow for a transplant procedure. Side effects of radiation include fever, irritability, hair loss, headaches, nausea, and appetite loss, in addition to skin irritations at the site where the χ rays are aimed. New treatment approaches being developed for children can reduce the side effects of radiation. These include hyperfractionation, which reduces the required dose of radiation, and tailored radiotherapy, which narrows the radiation to only a portion of the affected area. Surgery is the treatment of choice for localized cancers that are detected before they have spread. However, some cancers are more treatable by surgery than others, depending on the accessibility of the tumor. Surgery is often used in conjunction with radiation and/or chemotherapy to prevent a relapse, because if even a single cancer cell is left after the operation, it can lead to renewed abnormal growth and the recurrence of the tumor.

INCLUSION CRITERIA A preliminary list of cancers and related topics was compiled from a wide variety of sources, including professional medical guides and textbooks, as well as consumer guides and encyclopedias. The advisory board, made up of medical doctors and oncology pharmacists, evaluated the topics and made suggestions for inclusion. Final selection of topics to include was made by the advisory board in conjunction with the Gale editor. ABOUT THE CONTRIBUTORS The essays were compiled by experienced medical writers, including physicians, pharmacists, nurses, and other health care professionals. The advisors reviewed the completed essays to ensure that they are appropriate, up-to-date, and medically accurate. HOW TO USE THIS BOOK The Gale Encyclopedia of Cancer has been designed with ready reference in mind. Straight alphabetical arrangement of topics allows users to locate information quickly. Bold-faced terms within entries direct the reader to related articles. Cross-references placed throughout the encyclopedia direct readers from alternate names and related topics to entries. A list of key terms is provided where appropriate to define unfamiliar terms or concepts. A list of questions to ask the doctor is provided whenever appropriate to help facilitate discussion with the patient's physician. The Resources section for non-drug entries directs readers to additional sources of medical information on a topic. Valuable contact information for organizations and support groups is included with each cancer type entry. Appendix II at the back of Volume II contains an extensive list of organizations arranged in alphabetical order. A comprehensive general index guides readers to all topics mentioned in the text. A note about drug entries :Drug entries are listed in alphabetical order by common generic names . However, because many oncology drugs have more than one common generic name, and because in many cases, the brand name is also often used interchangeably with a generic name, drugs can be located in one of three ways. The reader can: find the generic drug name in alphabetical order, be directed to the entry from an alternate name cross-reference, or use the index to look up a brand name , which will direct the reader to the equivalent generic name entry. If the reader would like more information about oncology drugs than these entries provide, the reader is encouraged to consult with a physician, pharmacist, or the reader may find helpful any one of a number of books about cancer drugs. Two that may be helpful are: D. Solimando's Drug Information Handbook for Oncology , or R. Ellerby's Quick Reference Handbook of Oncology Drugs . GRAPHICS The Gale Encyclopedia of Cancer contains over 200 full-color illustrations, photos and tables. Eleven illustrations of various body systems can be found in the front matter of the book, and these can help the reader to understand which cancers may affect which organs, and how the various systems interact. ACKNOWLEDGMENTS The editor would like to express appreciation to the following medical professionals who reviewed several entries within their areas of expertise for the Gale Encyclopedia of Cancer . Linda Bressler, Pharm.D., B.C.O.P. Clinical Associate Professor College of Pharmacy University of Illinois Chicago, Illinois Susan M. Mockus, Ph.D Scientific Consultant Seattle, Washington James H. Morse, M.D. Assistant Professor Division of Gastroenterology University of Virginia Health Sciences Center Charlottesville, Virginia PHOTO ACKNOWLEDGMENTS On the cover, clockwise from upper left: Colored computed tomography (CT) scan of a human brain. (Dept. of Clinical Radiology, Salisbury District Hospital, Science Source/Photo Researchers. Reproduced by permission.) Color digitized image of the herpes simplex virus. (Custom Medical Stock Photo. Reproduced by permission.) Colored CT scan revealing cancer of the liver. (Dept. of Clinical Radiology, Salisbury District Hospital, Science Source/Phot

Cancer is not just one disease, but a large group of diseases characterized by uncontrolled and abnormal growth of the cells in the human body and the ability of these cells to spread to distant sites (metastasis). If the spread is not controlled, cancer can result in death.

Cancer is a group of diseases characterized by uncontrolled growth of tissue cells in the body and the invasion by these cells into nearby tissue and migration to distant sites.

The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute is the most authoritative source of information on cancer incidence and survival in the United States. Established in 1973, SEER originally provided cancer incidence data for Connecticut, Iowa, New Mexico, Utah, and Hawaii, and for the metropolitan areas of Detroit and San Francisco-Oakland. Since then, a number of other areas have been added to the program, including the metropolitan areas of Atlanta, Seattle, and Los Angeles; counties in Georgia; Native-American populations in Arizona and Alaska; and the states of New Jersey, Louisiana, Kentucky, and California. SEER registries routinely collect data on cancer patients, demographics, primary tumor site, morphology, stage at diagnosis, first course of treatment, and follow-up for vital status. SEER data, publications, and resources are available at http://www.seer.cancer.gov . B RENDA K. E DWARDS ( SEE ALSO : Cancer ; Data Sources and Collection Methods ; Demography ; Epidemiology ; National Institutes of Health ; Vital Statistics )

Cancer is not just one disease, but a large group of diseases characterized by uncontrolled and abnormal growth of the cells in the human body and the ability of these cells to spread to distant sites (metastasis). If the spread is not controlled, cancer can result in death.

Cancer is not just one disease, but a large group of almost one hundred diseases. Its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites. If the spread is not controlled, cancer can result in death .

Cancer is characterized by uncontrolled growth of cells in the body and the ability of these malignant cells to spread (metastasize) to distant sites within the body. If the spread is not controlled, cancer can result in death. Cancer is not just one disease but a group of almost one hundred different types of malignant diseases.

Cancer is a disease characterized by the uncontrolled growth and spread of abnormal cells. Around the world, over 10 million cancer cases occur annually. Half of all men and one-third of all women in the United States will develop some form of cancer during their lifetime. It is one of the most feared diseases, primarily because half of those diagnosed with cancer in the United States will die from it. Cancer is a leading cause of death around the world, causing over 6 million deaths a year. The exact causes of most types of cancer are still not known, and there is not yet a cure for cancer. However, it is now known that the risk of developing many types of cancer can be reduced by adopting certain lifestyle changes, such as quitting smoking and eating a better diet .

A continuous process in which multiple alterations occur in genes that control cell division and differentiation that leads to cancer—the uncontrolled division and proliferation of cells. These genetic alterations are referred to as mutations, which are changes in the normal DNA sequence of a particular gene. Mutations may include deletions, chromosomal translocations, inversions, amplifications, or point mutations. Cancer genetics is the understanding of the genetic processes underlying the actual disease occurrence. This understanding plays a significant role in early detection, therapy, prevention, and prognosis.