Breast Cancer Drug Aromasin May Be Option for Some
It produced lower 5-year recurrence rates compared to tamoxifen, but didn't boost overall survival, study finds
The study was funded by the U.S. National Cancer Institute, Pfizer (which makes Aromasin), Ipsen (makers of an ovarian suppression drug) and the International Breast Cancer Study Group.
The study researchers combined the results of two phase 3 clinical trials, known as the Tamoxifen and Exemestane Trial (TEXT) and the Suppression of Ovarian Function Trial (SOFT).
All of the women in the studies had hormone receptor-positive breast cancer. They also all had their ovarian function suppressed to further thwart cancer growth.
Both studies included analysis of five years of treatment over a median follow-up of more than 5.5 years.
Compared to tamoxifen, Aromasin reduced the risk of breast cancer recurrence by 34 percent.
But, women taking Aromasin experienced more osteoporosis -- a condition caused by thinned bones. The rate of osteoporosis was 13.2 percent in the Aromasin group versus 6.4 percent in the tamoxifen group. Women taking Aromasin also reported more fractures, vaginal dryness, decreased sex drive and painful sexual intercourse. But, women on tamoxifen had more blood clots, hot flashes, sweating and urinary incontinence, according to the study.
Dr. Hope Rugo, clinical professor of medicine and director of the breast oncology and clinical trials program at the Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, wrote an editorial to accompany the study. The aromatase inhibitor led to more sexual problems, osteoporosis, muscle and joint symptoms, she said. These "may be more noxious to young women than the hot flushes experienced with tamoxifen," she wrote.
About half of the women in both treatment groups reported depression, she noted.
While the researchers didn't find a difference in overall survival, it may be too soon to see it, Rugo said. She believes a difference in overall survival might become evident, because the aromatase inhibitor was better at lowering recurrence or a second cancer.
The best use of the aromatase inhibitors in premenopausal women might be in those who have "higher-risk disease," she said, such as those with bigger tumors or more involvement of the lymph nodes.
Cost differences also could play a role in deciding on one drug over another, Rugo added. "Tamoxifen is very cheap," she said, but exemestane is more expensive.