1516 Background: Breast cancer risk assessment (RA) is rarely performed in the primary care setting due to uncertainty regarding the balance of harms and benefits in high risk women subsequently offered chemoprevention. We used a decision model to assess the potential clinical impact of several strategies involving use of routine RA in primary care. Methods: We developed a decision analytic model to compare routine breast cancer RA in primary care to usual care. The RA method was the Gail model, with a 5-year risk of >1.67% being designated as high risk (varied in sensitivity analyses). We assumed that high risk women would be offered 5 years of tamoxifen and that acceptance (70%) and compliance (68%) rates would be incomplete. For women receiving tamoxifen, the relative risk (RR) of incident estrogen-receptor positive invasive breast cancer was 0.31 over the 5 years of treatment, diminishing over the next 5 years after cessation of treatment. RR’s for the other health effects associated with tamoxifen were: vertebral fracture (0.74), endometrial cancer (2.41), stroke (1.6), pulmonary embolism (PE, 3.01), and deep vein thrombosis (DVT, 1.60). The non-breast cancer health effects of tamoxifen were assumed to pertain only to the 5 years of active therapy. All RR’s were applied to age-dependent population-based incidence rates; data sources included published epidemiologic and clinical trial data; model duration was 40 years. Results: In agreement with recommended clinical use of tamoxifen, the results were sensitive to age and the Gail threshold above which chemoprevention was recommended ( Table ). The number of women needed to screen (NNS) to prevent 1 case of breast cancer is 7-fold higher among women aged 50 compared to 65 with a Gail risk of 1.67% (719 vs. 104). Conclusions: The number of women offered treatment, as well as the clinical outcomes and NNS, resulting from routine breast cancer risk assessment varies with the age at RA and treatment threshold selected. [Table: see text] No significant financial relationships to disclose.
Breast Cancer Risk Assessment at the Time of Screening Mammography: Perceptions and Clinical Management Outcomes for Women at High Risk
