Shrinking Tumors

More than one million new cases of cancer will be diagnosed in the United States this year. More than 500,000 people will lose their battle with cancer this year. Oncologist Christopher Ryan, M.D., from the Oregon Health & Science Cancer Institute in Portland, says more positive cancer outcomes can be made possible by targeted cancer therapies. "We're moving away from our old-fashioned chemotherapy drugs, which are sort of indiscriminate poisons, to smartly designed cancer drugs," says Dr. Ryan, One such cancer drug is bevacizumab, also known by its brand name, Avastin.

Last year, the FDA approved bevacizumab as a first-line treatment for patients with metastatic colorectal cancer -- cancer that has spread to other parts of the body. Avastin, a monoclonal antibody, is the first product to be approved that works by preventing the formation of new blood vessels, a process known as angiogenesis. Antibodies are what the body uses to fight off foreign material like bacteria, viruses or toxins. They are the body's natural defense mechanism against infection. Monoclonal antibodies are antibodies produced in a laboratory to target a very specific invader. Because of their precision, it is expected that they may be more effective than standard chemotherapy with fewer side effects. Avastin was shown to extend patients' lives by about five months when given intravenously as a combination treatment along with standard chemotherapy drugs for colon cancer. The drug is believed to work by targeting and inhibiting the function of a natural protein called "vascular endothelial growth factor" (VEGF) that stimulates new blood vessel formation. When VEGF is targeted and bound to Avastin, it cannot stimulate the growth of blood vessels, thus denying tumors blood, oxygen and other nutrients needed for growth.

COMBINATION THERAPY: Kevin Billingsley, M.D., is a surgical oncologist at Oregon Health & Science Cancer Institute. He says Avastin, combined with other chemotherapies, can make it possible to remove tumors once considered too large and risky. By "shrinking" these tumors, doctors are now able to remove them. Avastin is given along with the chemotherapy combination known as IFL. IFL consists of irinotecan, 5-fluorouracil (5-FU), and leucovorin. The FDA reports that in clinical trials there was longer survival and tumor control in patients who received the combination of IFL plus Avastin than among those who received IFL without Avastin. The average time before tumors started regrowing or new tumors appeared was four months longer than patients who did not receive Avastin.

SIDE EFFECTS: The FDA reports Avastin does have some side effects. Serious, but uncommon, side effects of Avastin include formation of holes in the colon (gastrointestinal perforation), which typically requires surgery and sometimes leads to intra-abdominal infections, impaired wound healing, and bleeding from the lungs or internally. Other, more common, side effects are high blood pressure, fatigue, blood clots, diarrhea, lowered immunity to diseases, headache, appetite loss and mouth sores.
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