Women at high risk of developing breast cancer reluctant to take tamoxifen for prevention

Even when informed about risks, benefits, only 6 percent would take drug

Even when women at high-risk of breast cancer are well-informed about the risks and benefits of using the drug tamoxifen for prevention, only 6 percent said they were likely to take it.

Researchers at the University of Michigan Comprehensive Cancer Center created a decision aid designed to inform women about the risks and benefits associated with tamoxifen, a drug that was first used to stop breast cancer from returning and has recently been shown to prevent breast cancer in the first place.

The U-M decision aid gave objective information about tamoxifen and was tailored to each woman's health history. The study targeted women who were at high risk of developing breast cancer within the next five years; 632 women participated.

"Tailored information is critical because the risks and benefits vary across women. This is one of the most detailed tailored decision aids to address breast cancer prevention. The information about the risks and benefits of tamoxifen was tailored to each woman's health history. That means, when women read this decision aid, they learned about how the drug was likely to affect them given their age, race, breast cancer history and medical history," says lead author Angela Fagerlin, Ph.D., associate professor of internal medicine at the U-M Medical School and a research investigator at the VA Ann Arbor Healthcare System.

After viewing the decision aid, 41 percent of women could correctly answer six questions about the risks and benefits of tamoxifen, while 63 percent correctly answered at least five of the six questions.

Despite this understanding, only 29 percent of women said they were likely to seek out more information about tamoxifen, and only 29 percent said they would ask their doctor about it. A scant 6 percent of women said they were likely to take tamoxifen.

Three months later, the researchers found that fewer than 1 percent of participants had started taking tamoxifen, and fewer than 6 percent had either talked to their doctor or sought more information.

Results of the study appear online in the journal Breast Cancer Research and Treatment.

"For any given woman, there is not a right or wrong answer in regards to whether she should take tamoxifen to prevent a first diagnosis of breast cancer. The goal of decision aids is to explain the risks and benefits in a clear way so that the woman is able to weigh these factors and make an informed decision about what is best for her," Fagerlin says.

While as many as 10 million women could be eligible to take tamoxifen to prevent breast cancer, few choose to do so.

Side effects were the biggest concern about tamoxifen cited in this study, with 80 percent of the participants worried about this. The side effects of tamoxifen include hormonal symptoms, including hot flashes, and sexual problems, as well as rare incidences of endometrial cancer, blood clots or cataracts.

"Experts have bemoaned the dearth of women taking these pills, worried that word has not gotten out about tamoxifen's ability to prevent breast cancer in high risk women. Our study shows that even when the word does get out, most women are too concerned about the pill's side effects to want to take it," says senior author Peter Ubel, M.D., professor of internal medicine and director of the Center for Behavioral and Decision Sciences in Medicine at U-M.

Breast cancer statistics: 194,280 Americans will be diagnosed with breast cancer this year and 40,610 will die from the disease, according to the American Cancer Society