Bridging the age gap: a new prognostic model that predicts survival and aids in primary treatment decisions for older women with ER-positive early breast cancer

Introduction: Using cancer registry data, a prognostic model was developed and validated. This underpins an online decision support tool, informing primary treatment choice for women aged 70+ with hormone-receptor-positive early breast cancer. Patients and methods: 23 842 women, diagnosed 2002-2010 in the Northern and Yorkshire and West Midlands English regions, met inclusion criteria. Primary treatment options of surgery with endocrine therapy or primary endocrine therapy were compared. Models predicting hazard of breast cancer specific mortality and hazard of other cause mortality were combined to derive survival probabilities. External validation used Eastern Cancer Registration and Information Centre data (N=14 526). Results: Overall model calibration was good. At 2 and 5 years, predicted breast cancer and other cause mortality differed from observed by less than 1%. At 5 years, there were slight over predictions in breast cancer mortality (Predicted v Actual: 2 629 v 2 556, P-value 0.78) and all-cause mortality (6 399 v 6 320, P-value 0.14). The discrepancy varied between subgroups. Model discrimination was 0.75 or above for all mortality measures. Conclusions: Our study developed a prognostic model for older women with ER positive early breast cancer. A prospective cohort study, part of the Bridging the Age Gap in Breast Cancer project, will provide a rich dataset to further assess the effects of surgery on survival.