Short-term mortality in older patients treated with adjuvant chemotherapy for early-stage breast cancer.

Chemotherapy for early-stage breast cancer has lowered cancer recurrence and deaths. However, short-term mortality rates due to cancer or treatment in the general population remain largely unknown. In this study, we evaluate the short-term mortality rate and the determinants of such outcome among a cohort of older breast cancer patients treated with adjuvant chemotherapy. This is a population-based study based on the Surveillance, Epidemiology, and End Results Program (SEER)-Medicare and the Texas Cancer Registry (TCR)-Medicare databases. Patients diagnosed with early-stage breast cancer between 2003 and 2011 who were 66 years or older and were treated with adjuvant chemotherapy within 6 months of diagnosis were included. Short-term mortality was defined as death from any cause within one year of breast cancer diagnosis. Descriptive statistics and multivariable logistic regression modeling were used for the analysis. Of the 21,536 patients included, a total of 625 (2.9 %) died within one year of breast cancer diagnosis. In multivariate analysis, older age (using 66-70 as reference category; 71-75 years OR 1.31, 95 % CI 1.05-1.62; 76-80 years OR 1.73, 95 % CI 1.36-2.19; >80 years OR 3.48, 95 % CI 2.7-4.48) and higher comorbidity index (using Charlson score of 0 as a reference, those with score of 1 or >2 had higher risk OR 1.46, 95 % CI 1.19-1.8 and OR 2.98, 95 % CI 2.42-3.67, respectively) were associated with the increased risk of short-term mortality. Other factors significantly associated with the outcome were higher grade and stage, ER-negative status, poor census tract area, and mastectomy. The findings of this study revealed that, in this large cohort of older breast cancer patients treated with adjuvant chemotherapy, 2.9 % of the population died within one year of breast cancer diagnosis. Finally, it was concluded that tumor- and patient-related characteristics were associated with short-term death. Our findings add relevant information that can be used by clinicians when balancing the risk.