The Influence of Medical Comorbidities on Survival Disparities in a Multiethnic Group of Patients with De Novo Metastatic Breast Cancer.

Background: The influence of common medical comorbidities on mortality and racial/ethnic disparities in mortality among women with metastatic breast cancer remains largely unknown.

Methods: In this longitudinal study, women with newly diagnosed stage IV breast cancer were identified in a large, diverse, integrated healthcare delivery system from January 2009 to December 2017 (n = 995) and followed through December 31, 2018, for all-cause (overall) and breast cancer-specific mortality via electronic health records. We computed overall and breast cancer-specific mortality rates by race/ethnicity and Elixhauser comorbidity index (ECI).