cancer - Treatment
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.

• • cancer - Treatment - Surgery
    • In theory, cancers can be cured if entirely removed by surgery, but this is not always possible. When the cancer has metastasized to other sites in the body prior to surgery, complete surgical excision is usually impossible. In the Halstedian model of cancer progression, tumors grow locally, then spread to the lymph nodes, then to the rest of the body. This has given rise to the popularity of local-only treatments such as surgery for small cancers. Even small localized tumors are increasingly recognized as possessing metastatic potential.
  • cancer - Treatment - Radiation therapy
  • cancer - Treatment - Chemotherapy
  • cancer - Treatment - Targeted therapies
  • cancer - Treatment - Immunotherapy
  • cancer - Treatment - Hormonal therapy
  • cancer - Treatment - Symptom control
    • Although the control of the symptoms of cancer is not typically thought of as a treatment directed at the cancer, it is an important determinant of the quality of life of cancer patients, and plays an important role in the decision whether the patient is able to undergo other treatments. Although all practicing doctors have the therapeutic skills to control pain, nausea, vomiting, diarrhea, hemorrhage and other common problems in cancer patients, the multidisciplinary specialty of palliative care has arisen specifically in response to the symptom control needs of this group of patients.
  • cancer - Treatment - Complementary and alternative
    • Complementary and alternative medicine (CAM) treatments are the diverse group of medical and health care systems, practices, and products that are not part of conventional medicine. Oncology, the study of human cancer, has a long history of incorporating unconventional or botanical treatments into mainstream cancer therapy. Some examples of this phenomenon include the chemotherapy agent paclitaxel, which is derived from the bark of the Pacific Yew tree, and ATRA, all-trans retinoic acid, a derivative of Vitamin A that induces cures in an aggressive leukemia known as acute promyelocytic leukemia. Many "complementary" and "alternative" medicines for cancer have not been studied using the scientific method, such as in well-designed clinical trials, or they have only been studied in preclinical (animal or in-vitro) laboratory studies. Many times, "complementary" and "alternative" medicines are supported by marketing materials and "testimonials" from users of the substances. Frequently, when these treatments are subjected to rigorous scientific testing, they are found not to work. A recent example was reported at the 2007 annual meeting of the American Society of Clinical Oncology: a Phase III clinical trial comparing shark cartilage extract to placebo in non-small cell lung cancer demonstrated no benefit of the shark cartilage extract, AE-491.
  • cancer - Treatment - Hormonal imbalances
    • Some hormones can act in a similar manner to non-mutagenic carcinogens in that they may stimulate excessive cell growth. A well-established example is the role of hyperestrogenic states in promoting endometrial cancer.
  • cancer - Treatment - Immune system dysfunction
    • HIV is associated with a number of malignancies, including Kaposi's sarcoma, non-Hodgkin's lymphoma, and HPV-associated malignancies such as anal cancer and cervical cancer. AIDS-defining illnesses have long included these diagnoses. The increased incidence of malignancies in HIV patients points to the breakdown of immune surveillance as a possible etiology of cancer. Certain other immune deficiency states (e.g. common variable immunodeficiency and IgA deficiency) are also associated with increased risk of malignancy.
  • cancer - Treatment - Heredity
    • Most forms of cancer are "sporadic", and have no basis in heredity. There are, however, a number of recognised syndromes of cancer with a hereditary component, often a defective tumor suppressor allele. Famous examples are:
  • cancer - Treatment - Other causes
    • A few types of cancer in non-humans have been found to be caused by the tumor cells themselves. This phenomenon is seen in Sticker's sarcoma, also known as canine transmissible venereal tumor. The closest known analogue to this in humans is individuals who have developed cancer from tumors hiding inside organ transplants.