Dr. Susan Love Research Foundation | Breast Cancer

In families where women are genetically predisposed to getting breast cancer because of an inherited gene, we typically find that there are several family members who had premenopausal, bilateral breast cancer and/or ovarian cancer. Because your mother and aunt were both postmenopausal when they were diagnosed, it is less likely that their breast cancer is related to a genetic predisposition.

Still, it makes sense that you would be thinking about taking tamoxifen. The data we have on the use of tamoxifen for risk reduction comes from the Breast Cancer Prevention Trial. This study enrolled women who were at high risk for developing breast cancer because they had a family history of breast cancer or had been diagnosed previously with atypical hyperplasia or lobular carcinoma in situ. Half of the women were given tamoxifen for five years; the other half were given a placebo.

The results from this trial were first presented in 1998. Final results were published in 2005. At that time, after seven years of follow-up, researchers found that 145 cases of invasive breast cancer had developed among the women taking tamoxifen compared to 250 cases in the women who had been given a placebo. In a group of more than 13,000 women, those aren't very large figures. Tamoxifen was also found to reduce a woman's risk of developing atypical hyperplasia.

The Breast Cancer Prevention Trial found that there were clear risks from taking tamoxifen. Women taking tamoxifen were at increased risk for cardiovascular disease, stroke, gallbladder disease, blood clots in the legs, cataracts, and uterine cancer. These may be risks worth taking to cure cancer, but we need to determine whether risk is warranted in the prevention setting. In the prevention trial some women died from a pulmonary embolism they got trying to prevent a cancer they might never have developed in the first place.

You may also want to consider the drug raloxifene (brand name Evista) for breast cancer prevention. In 2006, researchers reported the results from the STAR trial. This was a breast cancer prevention trial that compared tamoxifen with raloxifene, a drug used to prevent osteoporosis. The STAR trial found that raloxifene and tamoxifen were basically equivalent in terms of their ability to prevent invasive cancer. Both drugs reduced the risk of breast cancer by about 50 percent.

That doesn't mean an individual woman's risk of getting cancer was cut in half. What it does mean is that in a group of 1,000 high-risk women not taking tamoxifen or raloxifene, 8 would be expected to develop breast cancer, while in a group of 1,000 high-risk women taking tamoxifen or raloxifene, 4 would be expected to get the disease. It is important to note that we do not have any data that show a survival benefit from taking tamoxifen or raloxifene, only a benefit in reducing the risk of the development of disease.

The difference between the two drugs was in their side effects. Women on tamoxifen were more likely to experience hot flashes, while women on raloxifene were more likely to gain weight. However, a study that evaluated quality of life found it to be about the same in both groups of women. As a result, both drugs are now considered options for breast cancer prevention.

Another option you may want to consider is ductal lavage. Ductal lavage is a washing procedure that can identify cancerous and precancerous cells in the milk ducts of the breast. It is currently approved for use in women who are at high risk for developing breast cancer. The information you gain from the ductal lavage procedure may help you determine if taking tamoxifen or raloxifene is a good option for you right now.