Abstract P5-13-01: Uptake of breast cancer chemoprevention among high-risk women and those with ductal carcinoma in situ.

Abstract

Background: Chemoprevention with antiestrogens, such as tamoxifen, raloxifene, and aromatase inhibitors (AIs), reduces breast cancer incidence in high-risk women. However, uptake has been poor in the prevention setting. We examined demographic and clinical factors that influenced chemoprevention uptake in women with an elevated Gail risk score (≥1.67%), lobular/ductal carcinoma in situ (LCIS/DCIS), and/or BRCA mutation carriers. Methods: We enrolled women prospectively without a diagnosis of invasive breast cancer, who were seen for an initial consultation by breast surgery or medical oncology at Columbia University Medical Center. Eligibility for chemoprevention included a 5-year Gail risk ≥1.67%, LCIS, known BRCA1 or BRCA2 mutation, or hormone receptor (HR)-positive DCIS. Demographic and risk factor data were collected from a self-administered baseline questionnaire and clinical data from medical chart review, including prior/current chemoprevention, type of antiestrogen, duration of use, and toxicities. Differences in distribution of risk factors between women who ever took chemoprevention and those who did not were examined using chi-square statistics or Fisher's exact test. We used log-binomial regression models to estimate relative risks (RRs) and 95% confidence intervals (95% CI) using chemoprevention uptake as the dependent variable. A subset of high-risk women completed questionnaires assessing their attitudes towards chemoprevention and perceived risks/benefits. Results: Among 412 women enrolled between March 2007 and April 2013, 316 (77%) were eligible for chemoprevention. Main reasons for ineligibility included 5-year Gail risk <1.67% (40%), age <35 (24%), HR-negative DCIS (17%), opting for bilateral mastectomies (11%), and medical contraindications (8%). Among those eligible for chemoprevention, median age 53 (26-88); White/Hispanic/Black/Asian/other (%): 55/29/8/7/1; risk category, 5-year Gail risk ≥1.67%/LCIS/DCIS/BRCA mutation (%): 36/22/40/2. Overall, 162 (51%) women started an antiestrogen (72% for DCIS and 37% among high-risk women), including 114 on tamoxifen, 40 on raloxifene, and 11 on an AI. Early discontinuation occurred in 27 (18%) women, but 7 switched to a different antiestrogen. In univariable analysis, postmenopausal status and medical oncology referral were associated with higher chemoprevention uptake. In multivariable analysis, only higher risk was a significant predictor of chemoprevention uptake. Among the subset of women who completed additional questionnaires on attitudes towards chemoprevention, they reported that the most important factors in chemoprevention decision-making included their healthcare provider (50%), results of chemoprevention studies (44%), and knowledge about others’ experience with chemoprevention (44%). The majority (69%) were concerned about side effects, specifically blood clots with tamoxifen and raloxifene and bone fractures with AIs. Conclusions: In high-risk women seen at an academic breast center, chemoprevention uptake was relatively high compared to the published literature. Further research is needed to determine how the risks and benefits of chemoprevention are best communicated to women to enhance informed decision-making and increase uptake of chemoprevention strategies. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-13-01.