Treatment strategies and survival outcomes in older women with breast cancer: a comparative study between the FOCUS cohort and Nottingham cohort

Objective: Clinical trials investigating breast cancer treatment often exclude or misrepresent older adults. This study compares treatment patterns and survival of older women diagnosed with breast cancer between a Dutch and a British observational cohort.Materials and Methods: Women aged 70 years and older diagnosed with breast cancer after 1990 with a T0-T2 tumor stage and no evidence of metastatic disease were included from a population-based cohort in the Netherlands and a British hospital-based cohort in Nottingham. Main outcomes were proportions of local and systemic treatment, ten-year overall survival and ten-year relative survival for each cohort.Results: 1439 patients from Nottingham and 2180 patients from the Netherlands were included. Median follow-up was 12.4 years (IQR 11.0–14.0) in the FOCUS cohort and 6.4 years (IQR 6.2–6.8) in the Nottingham cohort. British patients were more likely to receive primary endocrine therapy (50.0% vs 7.5%, P