Avastin May Help Fight Early Breast Cancer
Studies May Reopen Discussions About Benefits of Avastin for Breast Cancer
Testing Avastin for Early-Stage Breast Cancers continued...
Among women with triple-negative tumors, the rates of complete response were 27.9% for women on standard chemotherapy and 39.3% in those who also got Avastin.
In contrast, women with cancer that was sensitive to hormones had about the same results whether or not they got Avastin. “We didn’t really expect that,” says researcher Gunter von Minckwitz, MD, associate professor of gynecology at the University of Frankfurt and chair of the German Breast Group. “Almost all the effect comes from this triple-negative group.”
He says there is some clinical data to suggest that tumors that don’t respond to hormones may rely more heavily than other kinds of cancers on the development of new blood vessels for growth.
Avastin shuts down the ability of tumors to grow new vessels, thus starving the cancer of its food supply.
When researchers in the U.S. took a similarly close look at their data, they found the opposite.
Avastin’s effects were more pronounced among women with breast cancer that was driven by either the hormones estrogen or progesterone. Among these women, 15% on traditional chemotherapy saw their tumors go away compared to 23% of the group that also got Avastin.
“It may indicate that [Avastin] has activity [in breast cancer], and that activity may be more profound in certain subsets of patients,” says researcher Harry Bear, MD, a surgical oncologist at Virginia Commonwealth University School of Medicine in Richmond.
Both studies were supported in part by Roche, the company that makes Avastin. Other financing for the research came from government grants and the manufacturers of the chemotherapy drugs that were tested.
Do the Benefits of Avastin Outweigh Its Risks?
In both studies, women who got Avastin had more side effects than those with standard chemotherapy. Those included fevers with low white blood cell counts, ulcers in the mouth and digestive tract, peeling of the skin on the hands and feet, infections, and high blood pressure.
While those problems are serious, researchers say going through some bad complications may be worth it if a woman can improve her chance of survival.
“In this setting, cure of the patient is the aim. Therefore, having bad side effects that will eventually go away may be worth it,” says von Minckwitz.
Bear agrees, and says use of the drug in this way will hinge upon whether or not it actually improves a woman’s chance of survival.
“If it improves survival, the risks will probably be worthwhile,” Bear says.
But independent experts caution against making too much of the small differences Avastin seemed to make.
“I would not give Avastin to any patient in the [pre-surgery] setting based on these data,” Aman U. Buzdar, MD, a medical oncologist and professor of medicine in the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center in Houston.