For other uses, see Cancer (disambiguation).
When normal cells are injured or older, die by apoptosis, but cancer cells avoid apoptosis.
Cancer is a disease in which the body produces an excess of malignant cells (known as carcinogens, or cancer), with growth and division beyond the normal (invasion of surrounding tissue, and sometimes metastasis). Metastasis is the spread at a distance, mainly via lymphatic or blood, the cancer stem cells, and growth of new tumors in the destinations of thesemetastases. These properties differentiate the benign from malignant tumors, which are limited and do not invade or metastasized. Most cancers do not form tumors, but some (such as leukemia).
Cancer can affect all ages, even fetuses, but the risk of the more common with increasing age. Cancer causes about 13 of all deaths. According to the American Cancer Society, 7.6 million people died of cancer in the world during 2007.
The cancer is caused by abnormalities in the genetic material of cells. These abnormalities may be carcinogenic, as radiation (ionizing, ultraviolet, etc), chemicals (from industry, snuff smoke and pollution in general, etc) or infectious agents. Other genetic abnormalities are acquired during cancer normal DNA replication, not corrected the errors that occur during the same or are inherited and therefore present in all cells from birth (causing an increased likelihood of triggering disease). There are complex interactions between carcinogens and genetic material, one reason why some individuals develop cancer after exposure to carcinogens and others are not. New aspects of the genetics of cancer, such as DNA methylation and microARNs, are being studied as important factors to consider for their involvement.
The genetic abnormality found in cancer cells could be of point mutation, translocation, amplification, deletion, and profit / loss of an entire chromosome. There are genes that are more susceptible to mutations that trigger cancer. These genes, when in its normal state, are called protooncogenes, and when they are mutated are called oncogenes. What these genes often encode growth factor receptors, so the genetic mutation causes the receptor produced is permanently activated, either encode growth factors in whether, and the mutation may have produced growth factors in excessive and uncontrolled.
The cancer is generally classified by tissue from which cancer cells originate. A definitive diagnosis requires histological examination, although early indications of cancer may be given after symptoms or radiography. Many cancers can be treated and some cured, depending on the type, location and stage or state in which they are located. Once identified, is treated with the combination of surgery, chemotherapy and radiotherapy. According to research, treatments are specified according to the type of cancer, and recently also of the patient. There was also significant progress in developing drugs that act on specific molecular abnormalities in certain tumors and minimize damage to normal cells. The diagnosis of cancer in this patient, largely influenced by the type of cancer, as well as the stage or the extent of the disease (often in the initial state is often confused with other diseases where there is no appropriate differential diagnoses) .