Background: The National Surgical Adjuvant Breast and Bowel Project (NSABP) P-1 trial demonstrated that tamoxifen reduces the incidence of new breast cancers by 49% in women at increased risk for breast cancer development. Tamoxifen does have side effects, however, including marginally increased risks of endometrial cancer and thromboembolic events. In this study, women at increased risk for breast cancer development were offered tamoxifen. Their knowledge of tamoxifen as a chemopreventive agent was assessed, and factors influencing their acceptance of tamoxifen and willingness to take it were determined.
Methods: Forty-three patients were identified who qualified to take tamoxifen for primary prevention. Patients qualified by having at least a 1.7% 5-year risk of developing breast cancer, the criteria for entry into the NSABP P-1 trial. Patients initially completed questionnaires designed to assess their knowledge of tamoxifen and its associated risks and benefits. Patients were then provided neutral educational sessions and literature delineating the actual risks and benefits of tamoxifen. Subsequently, patients' decisions regarding taking tamoxifen were reassessed.
Results: Mean patient age was 52.8 years, with a range of 39 to 74 years. Ten patients (23.2%) qualified based on the presence of lobular carcinoma in situ (LCIS), seven patients (16.3%) qualified based on increased risk secondary to age >60 years, and 26 patients (60.5%) age range 35 to 59 qualified based on risk profiles demonstrating significantly increased risk. Of the total 43 patients, two (4.7%) elected to start taking tamoxifen. Fifteen patients (34.8%) declined immediately, and 26 patients (60.5%) were undecided initially but ultimately declined. Educational sessions did not influence patients' decisions. Fear of side effects, including endometrial cancer, thromboembolic events, and menopausal symptoms, was the most commonly cited reason for declining to take tamoxifen.
Conclusions: In this study, the vast majority of patients at increased risk for breast cancer perceived that the risks of taking tamoxifen outweighed the benefits and declined to take it.