CANCER
Cancer is a group of diseases in
which cells are aggressive (grow and divide without respect to normal limits),
invasive (invade and destroy adjacent tissues), and sometimes metastatic (spread
to other locations in the body). These three malignant properties of cancers
differentiate them from benign tumors, which are self-limited in their growth
and don't invade or metastasize (although some benign tumor types are capable
of becoming malignant). Cancer may affect people at all ages, even fetuses,
but risk for the more common varieties tends to increase with age.Cancer causes
about 13% of all deaths.According to the American Cancer Society, 7.6 million
people died from cancer in the world during 2007.Apart from humans, forms
of cancer may affect other animals and plants.
Cancer can be treated by surgery, chemotherapy, radiation therapy, immunotherapy, monoclonal antibody therapy or other methods. The choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient (performance status). A number of experimental cancer treatments are also under development.Complete removal of the cancer without damage to the rest of the body is the goal of treatment. Sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to spread to distant sites by microscopic metastasis often limits its effectiveness. The effectiveness of chemotherapy is often limited by toxicity to other tissues in the body. Radiation can also cause damage to normal tissue.Because "cancer" refers to a class of diseases, it is unlikely that there will ever be a single "cure for cancer" any more than there will be a single treatment for all infectious diseases.(1)
source
(1) wikipedia