Adding bevacizumab to docetaxel slows disease progression when used as first-line chemotherapy for patients with locally advanced or metastatic breast cancer, according to a presentation at the annual meeting of the American Society of Clinical Oncology.

Previous studies had shown that adding bevacizumab to paclitaxel doubled progression-free survival in patients with metastatic breast cancer. The current trial was the first phase III study to evaluate bevacizumab in combination with docetaxel, the taxane used more often in Europe, Asia, and Australia.

"This study shows the antiangiogenic approach to treating breast cancer is effective, regardless of which taxane drug it is combined with," said David Miles, MD, a professor and medical oncologist at the Mount Vernon Cancer Centre and the study's lead author.

"We found it does not add a great deal to the toxicity of chemotherapy, which should be reassuring to physicians recommending this course of treatment."

In the current study, the AVADO trial, 736 patients were randomized among three arms: placebo plus docetaxel, 15 mg/kg bevacizumab plus docetaxel, and 7.5 mg/kg bevacizumab plus docetaxel. The higher dose was the standard established in earlier breast cancer studies; however, the lower dose was the standard used to treat colorectal cancer.

After a median follow-up of 11 months, patients in the low-dose group were 21 percent less likely to have disease progression compared with patients who received docetaxel alone. High-dose patients were 28 percent less likely to have disease progression than patients who received docetaxel only.

The percentage of patients with tumor shrinkage was 44.4 percent in the placebo plus docetaxel group, 55.2 percent in the low-dose bevacizumab group, and 63.1 percent in the high-dose group. Because of the number of patients in the trial, it was not possible to statistically compare the two doses with each other.

Patients in the two bevacizumab groups had a slightly higher rate of severe side effects: 74.8 percent in the low-dose group and 74.1 percent in the high-dose group compared with 67.0 percent in the docetaxel plus placebo group.

The most common side effect attributed to bevacizumab was high blood pressure, which was treatable with medication. Severe bowel perforation, a toxicity seen in some other bevacizumab trials, occurred in two patients in the placebo arm and one patient in each of the experimental arms.