User:Peter A. Lipson/cancersandbox
The account of this former contributor was not re-activated after the server upgrade of March 2022.
Import from article for messing around with:
Cancer is a term used to refer to a wide variety of diseases that have in common uncontrolled cell proliferation. Cancers are generally classified by the cell or tissue type of origin. Groups of cells form "tissues", like the skin and the nerves, and all mature from forerunners that made up the outer layer of cells in the early embryo gastrula. Malignant growth entails both rapid cell division and loss of the inhibition for cells to contact and overgrow other cells, that is normally present. (more often involves lack of apoptosis and continued division, rather than actual increase in RATE of cell division)As clumps of cancer cells grow, then can form "tumors". Not all cancers form tumors. For instance, in most leukemias, the cancer cells are circulating through the blood, rather than forming discrete masses. Cancers, especially rapidly growing ones, can consume a great deal of energy, and can secrete various substances that cause a general decline in health.
Cancer can cause symptoms in a number of ways: by direct effect on the organ involved (i.e. a cough with lung cancer), by growing into a vital structure (i.e. prostate cancer obstructing the urethra), or by causing generalized malaise and anorexia. This last topic is less well understood.
When cancers are "early", they are usually small, when they are both late and widely disseminated, they generally involve a much greater portion of the body. That's one reason why early and limited cancers less obviously impair health, unless they happen to involve particularly vital regions of the body, like the brain. Since it is early (smaller) cancers that are most successfully treated, by and large, much of modern medicine has been devoted to finding means to diagnose malignancies early on, and public health campaigns have promoted education of citizens to early warning signs of the various kinds of cancer.
Although the origin of cancer in an epithelial tissue is strictly required for the most technically accurate use of the term, cancer, the word is often used, even by physicians and hospitals, to include all the diseases directly caused by malignant tumors and cells. For example, malignant tumors called sarcomas arise from abnormal muscle-type cells, and since these tissues are derived from mesothelium rather than from epithelium, that word sarcoma is used rather than cancer to name the tumor. Still, cancer centers and specialists include treatment of sarcoma in practice, despite the fact that sarcomas and cancers differ in the medical classification of malignant tumors. In other words, all types of malignant tumors are sometimes referred to as cancers, but one type of these malignancies: epithelial malignancies, are, even more strictly, known as cancers.
This introductory article will give a brief description of what a malignancy is, and how cells are thought to become malignant. That understanding is important as a basis to comprehend the medical and surgical treatment of cancers, and effective approaches to their prevention. After a general introduction to malignancies, major types of cancers (epithelial malignancies) are surveyed, with links provided for further information. The clinical emphasis is on human cancers, but references to cancers in other species of animals is also made. Although the frequencies and the aggresiveness of the various types of cancers vary according to species, generally, the basic biology of cancers is true for all species of vertebrate animals, including humans and domestic animals.
Overview
The term cancer refers to many different diseases. They all have in common uncontrolled cell proliferation (growth and division). Cancers are usually named for the organ or cell type that is originally involved. After beginning at one site, cancer may metastasize (spread) to other organs. The cancer is still named by its place or origin.
Types of Cancer
Data are for USA
- Most common cancers in men:
- Deadliest cancers in men:
- Lung
- Prostate
- Colon
- Pancreatic
- Leukemia
- Liver
- Stomach
- Most common cancers in women
- Breast
- Lung
- Colorectal
- Deadliest cancers in women
- Lung
- Breast
- Colorectal
- Pancreatic
- Uterus
- Stomach
Prevention and Screening
Preventative strategies are continuously being revised. Please see references below for up to date information.
- Breast cancer: In women without a family history of breast cancer, mammograms should be done yearly. Clinical breast exam by a medical professional should also be done yearly. Women who have had abortions are significantly more likely to contract breast cancer.
- Lung cancer: There are no currently accepted preventative guidelines
- Prostate cancer: evidence is inconclusive, but most doctors recommend yearly PSA blood test and digital rectal exam
- Colon cancer: in people without a family history of colon cancer, most sources recommend a colonoscopy at age 50, with further studies based on the results. Fecal occult blood testing should also be conducted yearly.
- Cervical cancer: yearly Pap smears should be done on all women who have been sexually active and have a cervix. Over age 65, women in monogamous relationships and recent normal Pap smears probably do not need to be screened as frequently.
- Testicular cancer: the evidence is unclear, however most physicians recommend routine testicular exams in young men.
- Skin cancer: keep skin protected from sunlight by use of clothing and sunscreen, and watch you skin for new moles, or changes in existing moles.
References
- http://www.cdc.gov
- http://www.cancer.org/docroot/stt/stt_0.asp
- http://www.ahrq.gov/clinic/pocketgd.htm