Tamoxifen has been shown to reduce risk of invasive and non-invasive breast cancer by almost 50 percent. However, tamoxifen also increases the risk of endometrial cancer, blood clots, cataracts, and more severe menopausal symptoms, such as hot flashes and night sweats.

Researchers at Beth Israel Deaconess Medical Center evaluated health-related and psychological factors involved in decision-making among 129 women eligible to receive tamoxifen (women with a five-year risk of developing cancer of 1.7% or greater). Women received counseling from physicians about potential risks and benefits of tamoxifen therapy, and were asked to complete questionnaires assessing demographics, personal and family health history, and emotional factors, including level of distress, anxiety about breast cancer, and optimism about the potential outcome of treatment. Post-menopausal women in the study were given the option of taking tamoxifen or enrolling in the STAR trial, a randomized study comparing five years of tamoxifen and raloxifene, another drug in the same class as tamoxifen.

Researchers followed up with study participants at two and four months to assess their treatment decision and their satisfaction with that decision.After two months, 29% of study participants decided to take tamoxifen; 27% opted to enroll on the STAR trial; 24% declined treatment; and 20% remained undecided. After four months, some participants had changed their decision, with most ultimately deciding against treatment—a total of 25.6% chose tamoxifen, 25.6% enrolled on the STAR trial, 35% declined treatment, and 14% of women remained undecided.

Researchers assessed the influence of health-related variables on participant decision-making, finding that, contrary to expectations, a family history of breast cancer did not increase the likelihood that women would choose tamoxifen. However, personal history, such as an abnormal biopsy, was highly correlated with the decision to take tamoxifen.Physician advice also influenced decision-making, with women receiving a physician recommendation more likely to take the drug.

Researchers also found that perception of risk and a lack of information influenced decisions about tamoxifen:

• Women in the study who declined treatment were more likely to report fear of side effects and believe that tamoxifen would not be an effective prevention strategy,

• Women who felt uninformed about their options were more likely to remain undecided, and

• Women who reported higher levels of anxiety about cancer and who perceived themselves to be at greater risk for breast cancer were more likely to choose tamoxifen.

Researchers also assessed how participants felt about their decision, finding that anxiety and psychological distress influenced whether or not they were satisfied with their decision.Women who cited fewer sources of information were more likely to feel dissatisfied with their decision.Although decision satisfaction did not vary between women who chose or declined treatment, those who experienced heightened anxiety about cancer or about treatment side effects were less likely to feel satisfied with their decision.

Researchers noted that previous studies suggest that dissatisfaction with their decision may lead some women to prematurely discontinue treatment, and underscored the need to help women make informed decisions.

“This study highlights the complexity of making important medical decisions, and underscores the need for improved patient-physician communication to help patients weigh the risks and benefits of therapy,” Dr. Bober added.“Women are willing to grapple with difficult decisions in order to reduce their risk of breast cancer. But for many women, the benefits of the best available preventive medication are not sufficient.”