(LifeWire) - Continuing research in to cancer has yielded various new treatment approaches, including new treatments for breast cancer. One of the latest developments, known as biological therapy, has attracted particular interest among researchers, doctors and patients.
Older cancer treatment strategies include radiation therapy (which uses x-rays to target the DNA in cancer cells, killing them), chemotherapy (which uses toxic drugs that kill rapidly dividing cells such as cancer cells) and hormone therapy (which fights certain cancer cells by interfering with their access to specific hormones that they need to grow and thrive).
Biological therapy harnesses the body's own power to combat cancer cells -- or to reduce the side effects of other treatments. The first three biological therapies to receive FDA approval for the treatment of breast cancer are:
- Herceptin (trastuzumab). First used to treat advanced breast cancer, it's now also approved for early stage treatment. Herceptin uses a laboratory-produced antibody (a protein made by the body to combat foreign invaders, such as viruses or bacteria). The antibody targets a protein called "HER2/neu" that's found on some breast cancer cells.
- Avastin (bevacizumab). It can be used to treat metastatic (widespread) breast cancer. Like Herceptin, it also employs laboratory-synthesized antibodies, which in this case bind to a substance required for the growth of new blood vessels that tumor cells need for survival.
- Tykerb (lapatinib). It is also used to treat advanced breast cancer, usually in conjunction with chemotherapy. This substance slips int o the cancer cell, disrupting the HER2/neu protein and interfering with signals necessary for cancer cell growth. Tykerb is often used when Herceptin has become ineffective.
Researchers are also working to develop so-called cancer vaccines. Like other vaccines, these take advantage of the fact that the body's immune system works most quickly and efficiently against enemies encountered in the past.
For example, vaccines in common use (such as those against measles and the flu) involve injecting a tiny bit of an inactivated virus in to the body. When the body's immune system encounters the virus, it gears up its machinery so that, if it ever encounters that particular threat in the future, it will be primed to respond rapidly, pumping out huge numbers of antibodies specifically designed to combat it.
A cancer vaccine works in the same way, intensifying normal immune mechanisms against cancer. By administering proteins or peptides that are associated with a particular type of cancer, the body's immune system is put in to a surveillance mode, allowing it to quickly identify and destroy any cancer cells that it comes across to prevent them from establishing themselves and becoming new or recurrent tumors. One such vaccine under study is a HER2/neu vaccine that can stimulate the body's own immune mechanisms to recognize and destroy cells bearing the HER2/neu protein.
Cancer vaccines, though, differ from vaccines against flu or the measles in that they aren't generally given to protect individuals who don't have the disease. An exception is the human papillomavirus vaccine Gardasil, which protects against cervical cancer, a disease largely caused by this virus.
Most other cancer vaccines are given to people who've already been diagnosed with that particular form of cancer. This sort of vaccination doesn't prevent cancer from occurring, but instead keeps the cancer cells from establishing themselves to form new or recurrent tumors.
Sometimes biologic therapy is used to aid in the administration of more conventional medicines, such as chemotherapy. For example, colony-stimulating factors (CSFs) help the bone marrow make adequate infection-fighting cells during the treatment to prevent infections and maintain dosing frequency. These CSFs stimulate the bone marrow and increase production of blood elements (red blood cells, white blood cells or platelets).
Disruption of these blood elements often accompanies chemotherapy and other cancer treatments. CSFs allow chemotherapy to be given with less risk of anemia, infection or bleeding -- associated, respectively, with reduced levels of red blood cells, white blood cells and platelets.
Sources:
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"Chemotherapy and You: Support for People With Cancer." cancer.gov. 29 Jun. 2007. National Cancer Institute. 13 May 2008.
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"What Is Immunotherapy?" cancer.org. 28 Mar. 2008. American Cancer Society. 13 May 2008.
Whittington, Paula J., M.P. Piechocki, H.H. Heng, J.B. Jacob, R.F. Jones, J.B. Back and W-Z Wei. "DNA Vaccination Controls Her-2+ Tumors That Are Refractory to Targeted Therapies." Cancer Research 68:18(2008): 7502-11. 17 Sep. 2008 (subscription).
