Abstract P2-10-04: Breast cancer risk assessment tool (BCRAT) predicted breast cancer incidence and breast cancer mortality in the women's health initiative

Abstract Purpose Commonly used breast cancer risk models estimate breast cancer incidence. However, such model performance, re-purposed to predict breast cancer mortality, are largely unknown. Therefore, we examined whether the BCRAT model predicts long-term breast cancer mortality in postmenopausal women in the WHI. Participants and Methods Of 161,808 WHI participants aged 50-79 years, after exclusions,145,408 were in the analysis. BCRAT risk was calculated, with incident breast cancers verified by central medical record review. Breast cancer mortality was related to BCRAT 5-year risk groups (< 1%, 1-2.99%, ≥ 3%) using unadjusted Cox proportional hazard models and in age-stratified, multi-variable models. An addition analysis compared proportion of participants with BCRAT risk ≥ 1.67% and ≥ 3% (former and current prevention thresholds). Results Of 145,408 participants, the ≥1.67% and the ≥3.0% risk groups included 40% and 9% of participants, respectively. Compared to women with BCRAT<1% risk, women with BCRAT ≥ 3% risk had more common breast cancer family history and lower BMI. After 20 years median follow-up, with 8,849 breast cancers and 1,076 deaths from breast cancer, risk of death from breast cancer in BCRAT risk group ≥ 3% was not higher compared to BCRAT risk group <1%. (Hazard Ratio [HR] 1.06 95% Confidence Interval [CI] 0.80-1.40, P = 0.76). Similarly, risk of death from breast cancer in BCRAT risk group 1-2.99% was not higher compared to BCRAT risk group <1 (HR 1.15 95% CI 0.93-1.43). Conclusions Current guideline recommendation for threshold for endocrine-targeted interventions substantially reduces postmenopausal prevention candidates from 40% to <10%. The BCRAT prediction model, even at the ≥ 3% 5-year risk threshold, does not identify women at significantly increased risk of death from breast cancer. Citation Format: Rebecca Nelson, Kathy Pan, Rowan Chlebowski, Thomas E Rohan, Joanne Mortimer, Jean Wactawski-Wende, Dorothy Lane, Laura Kruper. Breast cancer risk assessment tool (BCRAT) predicted breast cancer incidence and breast cancer mortality in the women's health initiative [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-10-04.