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:For other meanings of Cancer: see Cancer (disambiguation).When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis.
Cancer is a group of related diseases characterized by uncontrolled cell division. Currently, it is believed that cancers arise from both genetic and environmental factors that lead to aberant growth regulation of a stem cell population, or by the dedifferentiation of more mature cell types. Normally, cells proliferate only in response to injury, immune responses, or, in a few cases, to replace cells that have undergone apoptotic cell death. Mutations in DNA that lead to cancer appear to disrupt this orderly process.
The rapid proliferation of cells can lead to a tumor (or neoplasm) that is either benign (not cancerous) or malignant (cancerous). Benign tumors do not spread to other parts of the body or invade other tissues, and they are rarely a threat to life. Malignant tumors can invade other organs, spread to distant locations ( metastasize) and become life threatening.
1 Types of cancer
Cancers originate within a single cell. Hence, cancers can be classified by the type of cell in which it originates and by the location of the cell.
Carcinomas originate in epithelial cells, e.g. skin, digestive tract or glands. LeukemiaLeukemia leukaemia in international English) is a group of cancers of the blood-forming tissues. The word leukemia tends to be used as an umbrella term. In the 19th century, it was seen as one single, homogenous deadly disease, characterized by a white ap starts in the bone marrowBone marrow is the tissue comprising the center of large bones. It is the place where new blood cells are produced. Bone marrow contains stem cells which produce three types of blood cells: leukocytes, red blood cells, and platelets. Long bones" are tubul stem cells. LymphomaLymphoma is a general term for cancers that develop in the lymphatic system. Hodgkin's disease, discovered by Thomas Hodgkin in 1832, is one type of lymphoma. All other lymphomas are grouped together and are called non-Hodgkin's lymphoma. Prevalence Accor is a cancer originating in lymphatic tissueIn mammals including humans, the lymphatic vessels (or lymphatics are a network of thin tubes that branch, like blood vessels, into tissues throughout the body. Lymphatic vessels carry lymph a colorless, watery fluid originating from interstitial fluid (f. Melanoma arises in melanocyteMelanocytes are cells located in the bottom layer of the skin's epidermis. With a process called melanogenesis, they produce melanin, a pigment in the skin, eyes, and hair. In Caucasians, melanocytes are triggered by ultraviolet rays, thus they must be ins. SarcomaA sarcoma is a cancer of the bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. The term comes from a Greek word meaning "fleshy growth. Bone tumors osteosarcomas are also called sarcomas, but are in a separate category begins in the connective tissue of bone or muscle. Teratoma begins within germ cells.
1.1 Adult cancers
Adult cancers usually form in epithelial tissues and are believed often to be the result of a long biological process related to the interaction of exogenous exposures with genetic and other endogenous characteristics among susceptible people. Examples include: bladder carcinoma, blood (and bone marrow) - hematological malignancies, leukemia, lymphoma, Hodgkin's disease, non-Hodgkin's lymphoma, multiple myeloma, brain tumor, breast cancer, cervical cancer, colorectal cancer - in the colon, rectum, anus, or appendix, esophageal cancer, endometrial cancer - in the uterus, hepatocellular carcinoma - in the liver, gastrointestinal stromal tumor (GIST), laryngeal cancer, lung cancer, mesothelioma - in the pleura or pericardium, oral cancer, osteosarcoma - in bones, ovarian cancer, pancreatic cancer, prostate cancer, renal cell carcinoma - in the kidneys, rhabdomyosarcoma - in muscles, skin cancer (including benign moles and dysplastic nevi), stomach cancer, testicular cancer, and thyroid cancer.
