Breast cancer is a curable disease, but once it has metastasized it is considered treatable but not curable. The American Cancer Society estimates that 40,000 women die of metastatic breast cancer each year. Of those, Genentech estimates that 38,000 have tumors that might respond to Avastin.
"Athough metastatic breast cancer remains incurable despite drugs like Herceptin, Avastin and others, it is eminently treatable," said Dr. Joseph Sparano, associate chairman of the department of oncology at the Montefiore Medical Center in New York. "In my view, a drug that doubles the chance of controlling the disease but doesn't affect survival is just as useful as one that prolongs survival by a few months."
Genentech estimates that 75 percent of women found to have breast cancer that has already spread have tumors that are HER2-negative -- and thus may be helped by Avastin.
Avastin works by replicating the body's own weapons -- antibodies that block the growth of blood vessels that feed tumors.
Breast cancer is the second most common form of cancer and the second leading cancer killer among American women. According to the American Cancer Society, an estimated 178,000 women in the United states were diagnosed with breast cancer in 2007.