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Medical Oncology
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Chemotherapy
Chemotherapy is any treatment involving the use of drugs to kill cancer cells. Cancer chemotherapy may consist of single drugs or combinations of drugs, and can be administered through a vein, injected into a body cavity, or delivered orally in the form of a pill. Chemotherapy is different from surgery or radiation therapy in that the cancer-fighting drugs circulate in the blood to parts of the body where the cancer may have spread and can kill or eliminate cancers cells at sites that are a great distances from the original cancer. As a result, chemotherapy is considered a systemic treatment.
More than half of all people diagnosed with cancer receive chemotherapy. For millions of people who have cancers that respond well to chemotherapy, this approach helps treat their cancer effectively, enabling them to enjoy full, productive lives. Furthermore, many side effects once associated with chemotherapy are now easily prevented or controlled, allowing many people to work, travel, and participate in many of their usual activities while receiving chemotherapy.
Targeted Therapies
A targeted therapy is one that is designed to treat only the cancer cells and minimize damage to normal, healthy cells. Cancer treatments that "target" cancer cells may offer the advantage of reduced treatment-related side effects and improved outcomes.
Conventional cancer treatments, such as chemotherapy and radiation therapy, cannot distinguish between cancer cells and healthy cells. Consequently, healthy cells are commonly damaged in the process of treating the cancer, which results in side effects. Chemotherapy damages rapidly dividing cells, a hallmark trait of cancer cells. In the process, healthy cells that are also rapidly dividing, such as blood cells and the cells lining the mouth and GI tract, are also damaged. Radiation therapy kills some healthy cells that are in the path of the radiation or near the cancer being treated.
Newer radiation therapy techniques can reduce, but not eliminate this damage. Treatment-related damage to healthy cells leads to complications of treatment, or side effects. These side effects may be severe, reducing a patient's quality of life, compromising their ability to receive their full, prescribed treatment, and sometimes, limiting their chance for an optimal outcome from treatment.
Advances in science and technology have led to the development of several different types of targeted therapies. Each of these new treatments targets cancer through different mechanisms:
- Anti-angiogenic drugs starve the cancer cells of blood that they need to survive and grow.
- Monoclonal antibodies can locate cancer cells in the body by recognizing proteins that are more abundant in cancer cells than normal cells, called receptors. The monoclonal antibody may then cause its anti-cancer effect by blocking the receptor from binding with substances in the blood. Treatments that block receptors may also be called "receptor antagonists".
- Radioactive monoclonal antibodies are comprised of a radioactive substance attached to a monoclonal antibody, the latter of which acts as a homing device, and the radioactive substance kills the targeted cell.
- Tyrosine kinase inhibitors interact with the enzyme (protein) tyrosine, which is active in a complex signaling system that is used by some cancers as a survival mechanism to allow them to grow out of control. The drug Gleevec® (imitinib mesylate) is an example of this type of targeted therapy that inhibits a mutated form of tyrosine kinase and stops the abundant growth of cancerous white blood cells in chronic myeloid leukemia.
- Vaccines are synthetic substances that are made from a patient's own cancer cells and stimulate the body to recognize and attack cancer cells.
Biological Therapy
Biological therapy is referred to by many terms, including immunologic therapy, immunotherapy, or biotherapy. Biological therapy is a type of treatment that uses the body's immune system to facilitate the killing of cancer cells. Types of biological therapy include interferon, interleukin, monoclonal antibodies, colony stimulating factors (cytokines), and vaccines.
Hormonal Therapy
Hormones are naturally occurring substances in the body that stimulate the growth of hormone sensitive tissues, such as the breast or prostate gland. When cancer arises in breast or prostate tissue, its growth and spread may be caused by the body's own hormones. Therefore, drugs that block hormone production or change the way hormones work, and/or removal of organs that secrete hormones, such as the ovaries or testicles, are ways of fighting cancer. Hormone therapy, similar to chemotherapy, is a systemic treatment in that it may affect cancer cells throughout the body.
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