In The News

Mari Anne Fahrner, MD, St. Luke's Hospital

Medications to prevent breast cancer in high-risk women

Prior to the 1990's, little could be done to prevent breast cancer. But in the last 20 years, several prevention trials have provided compelling evidence that women with above average risk for breast cancer can decrease their risk with medications. The new field of chemoprevention of breast cancer, using medications to prevent the disease in high-risk women, supplements the growing body of knowledge regarding its detection and treatment.

The strongest risk factors for developing breast cancer are: female gender, advancing age and family history. These risk factors, of course, can not be changed. Women are considered to be at high risk if they are older than 60, have a first-degree family member (mother, sister or daughter) with breast cancer or a previous abnormal breast biopsy.

The first National Surgical Adjuvant Breast and Bowel Project (NSABP) breast cancer prevention trial enrolled almost 14,000 premenopausal and postmenopausal women at increased risk who took either a placebo (no medicine) or tamoxifen for five years. Prior to the trial, tamoxifen was only used if a patient was diagnosed with breast cancer. After seven years of follow up, researchers found that women who took tamoxifen had a 43 percent reduction in the development of breast cancer.

Then, in a study designed to evaluate the benefit of a drug similar to tamoxifen called raloxifene with regard to osteoporosis, researchers noted that the women treated with raloxifene had fewer breast cancers.

With this encouraging information, the NSABP launched a second prevention trial. In this study, postmenopausal women were treated with either tamoxifen or raloxifene. After almost four years, researchers found tamoxifen and raloxifene were equivalent in the prevention of invasive breast cancer.

As with all medications, side effects can occur. Tamoxifen carries a small risk of developing uterine abnormalities including cancer, and both medications carry a small risk of causing blood clots. Women who consider taking tamoxifen or raloxifene to lower breast cancer risk should discuss the risks and benefits of treatment with their primary care physicians.

Studies evaluating other medications for the prevention of breast cancer are ongoing and may eventually provide proactive options for a wider range of women.

Mari Anne Fahrner, MD, specializes in general surgery at St. Luke's Hospital. Call 314-205-6491 or visit her Physician Referral page.

This article was published in the St. Louis Post-Dispatch on August 27, 2009.