By Serena Gordon
WEDNESDAY, Dec. 28 (HealthDay News) -- Two new studies suggest that the drug Avastin may lengthen progression-free survival by about four months for women with ovarian cancer.
What isn't clear yet is whether adding Avastin (bevacizumab) will make a difference in overall survival. One study suggested it would, while the other study didn't find a difference in overall survival between two treatment groups.
"The bottom-line results are a 28 percent reduction in disease progression with patients on continued bevacizumab compared to the standard treatment group. There was a 3.8 month median difference in progression-free survival," said Dr. Robert Burger, author of one of the studies and director of the Women's Cancer Center at Fox Chase Cancer Center in Philadelphia.
"We still have to fine-tune or optimize this sort of new paradigm of treatment. This regimen [chemotherapy plus continued Avastin] could be considered a frontline option for patients with advanced ovarian cancer. However, there are some risks to the treatment, and we haven't shown an impact on overall survival. But, in the European trial, they saw an overall survival benefit," Burger added.
"I think the difficult reality is that these studies are not clear-cut," said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society. "The improvements in progression are modest and appear to be greater for women who have worse disease. What this ultimately means is that it's absolutely important for doctors treating women with advanced ovarian cancer to read these studies very carefully so they know who may benefit and the risks of treatment, and to counsel their patients very carefully before moving forward with Avastin treatment," Lichtenfeld explained.
"This is not a case where treatment can be initiated in every woman. The benefits for many women are modest at best," he added.
Results of both studies are published in the Dec. 29 issue of the New England Journal of Medicine. The studies were funded by Roche and Genentech (a Roche-owned company). Burger said Genentech played no role in the study design or analysis.
Burger's study included almost 1,900 women with newly diagnosed stage 3 or stage 4 epithelial ovarian cancer. All of the women had undergone surgery to remove as much cancer as possible. They were then randomly assigned to one of three treatment groups: standard treatment including paclitaxel and carboplatin chemotherapy; the Avastin-initiation group that included the standard chemotherapy and Avastin for the second through sixth treatment cycle; and the Avastin maintenance group that included chemotherapy plus Avastin for up to the 22nd treatment cycle.
The average progression-free survival was 10.3 months for the standard group, 11.2 months for the Avastin-initiation group and just over 14 months for the Avastin-maintenance group. There was no difference in overall survival for the three groups.
The European study included more than 1,500 women with varying types of ovarian cancer. Most had epithelial ovarian cancer, but the severity ranged from early-stage disease to stage 4. Seventy percent of the women enrolled in this study had stage 3 or stage 4 cancer.
The women were randomly assigned to receive either standard chemotherapy treatment or chemotherapy plus Avastin for up to 12 cycles of chemotherapy. The dose of Avastin used in this trial was half of what was used in Burger's trial.
Progression-free survival was 20.3 months for the standard group and 21.8 months for the standard therapy plus Avastin. In women who were considered at high risk for progression, the progression-free survival was 14.5 months on standard therapy and 18.1 months with the addition of Avastin. Overall survival in high-risk women was 28.8 months for women on standard chemotherapy and 36.6 months for standard therapy plus Avastin.
High blood pressure is a common side effect of Avastin, but Burger said that in most cases, it can be controlled with blood pressure medication. Another serious side effect associated with Avastin is bowel perforation, which means a hole opens in the bowel wall. This side effect occurred in fewer than 3 percent of women treated, but occurred twice as much in women taking Avastin.