Comorbidities, age and period of diagnosis influence treatment and outcomes in early breast cancer.

Survival for breast cancer (BC) is lower in eastern than northern/central Europe, and in older than younger women. We analysed how comorbidities at diagnosis affected whether selected standard treatments (STs) were given, across Europe and over time, also assessing consequences for survival/relapse. We analysed 7581 stage I/IIA cases diagnosed in 9 European countries in 2009-2013, and 4 STs: surgery; breast-conserving surgery plus radiotherapy (BCS + RT); reconstruction after mastectomy; and prompt treatment (≤6 weeks after diagnosis). Covariate-adjusted models estimated odds of receiving STs and risks of death/relapse, according to comorbidities. Pearson's R assessed correlations between odds and risks. The z-test assessed the significance of time-trends. Most women received surgery: 72% BCS; 24% mastectomy. Mastectomied patients were older with more comorbidities than BCS patients (