Other- and all-cause Mortality among women with breast cancer

Abstract

BackgroundAdvances in early detection and treatment of breast cancer (BrCA) have led to better survival. Consequently, more women with BrCA now die from non-BrCA causes. We investigated all-cause and other-cause (non-BrCA) survival among women with BrCA. MethodsFrom the Prostate, Lung, Colorectal and Ovarian (PCLO) cohort, we selected women diagnosed with BrCA from 1994-2014. To compare survival of cases to non-cases, we used exposure density sampling. We computed standard mortality ratios (SMRs) and performed Cox proportional hazards models with matched case-control sets, controlling for demographics (Model I) and additional covariates (Model II). We also examined survival by stage within BrCA cases. ResultsAmong 78,215 women enrolled in PLCO, there were 1211 in-situ and 4790 invasive BrCA cases. 15-year survival rates were 97.1 % (BrCA-specific) and 77.2 % (other-cause) among in-situ and 86.4 % (BrCA-specific) and 73.4 % (other-cause) among invasive cases. For other-cause mortality, in-situ cases had lower risk in models I (HR = 0.74; 95 % CI:0.62-0.89) and II (HR = 0.75; 95 % CI:0.62-0.92) versus controls. All-cause mortality HRs for in-situ cases were 0.83 (95 % CI:0.70-0.99) and 0.85 (95 % CI:0.70–1.02) in Models I and II, respectively. Other-cause mortality was similar among invasive cases and controls. Within BrCA cases, higher stage was associated with increased other-cause mortality; HRs were 1.2 (95 % CI:1.1–1.5) and 1.7 (95 % CI:1.2–2.3) for stage II and III/IV versus stage I (Model II). DiscussionMortality from other causes exceeded that of BrCA in both in-situ and invasive cases, highlighting the importance of managing patients’ chronic conditions during and following cancer treatment.