Ultima Vez Modificado: 1 de noviembre del 2001
Depending upon the type of cancer a patient has, they could exhibit various symptoms. The American Cancer Society has developed a general list of seven symptoms that could be warning signs of cancer :
Epidemiological studies are studies of cancer looking at various
factors such as diet, race, age, and environment. These studies
show that there are numerous factors that contribute to a patient
being diagnosed with cancer. Two such factors are carcinogens
and oncogenic viruses.
Carcinogens are substances known to cause and/or promote cancer. Carcinogens can be either man-made, such as cigarette smoke, or present naturally in the environment, as is ultraviolet radiation from the sun, both of which are known to play a major role in the development of cancer. Carcinogens can also enhance other factors that cause the cancer. Certain cancers develop slowly. It can take from 5 to 40 years for cancer to develop after exposure to a cancer-causing agent, making identification of carcinogens difficult. The number of exposures as well as the length of time exposed to carcinogens determine whether a cancer will develop, but there is no evidence that there is a "safe" level of any carcinogen. Some known carcinogens are:
|These are pictures from the BRCA1 lab. Scientists work here studying the gene which is thought to cause breast cancer.|
Oncogenes are genes within a cell that may initiate the cells'
transformation from normal to malignant. Some known oncogenes
are the BRCA 1 gene which is linked to breast cancer or the gene
linked to colon cancer. Oncogenic viruses are
viruses that are linked to cancer. There have been almost 40 oncogenic
viruses discovered including HIV, HPV (Human Papilloma Viruses),
herpes viruses, hepatitis B and C viruses, and retroviruses. Researchers
have found that the immune system may recognize the difference
between healthy cells and cancer cells and eliminate those that
become cancerous. Cancer may develop when the immune system breaks
down or is overwhelmed. This may account for the link between
HIV and cancer.
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