Prognostic Evaluation of the Charlson Comorbidity Index for Breast Cancer Patients by Propensity Score Matching Analysis

PURPOSE: The Charlson Comorbidity Index (CCI) is associated with the prognosis of patients with breast cancer. However, comorbidities are often confounded by both age and treatment course; therefore, it is essential to eliminate the influence of these factors. We analyzed the relationship between CCI scores and breast cancer prognosis using propensity score matching (PSM). METHODS: We retrospectively analyzed 1,403 patients with primary breast cancer who underwent curative surgery. After PSM, 764 patients were selected for analysis of clinicopathological and prognostic factors. RESULTS: After PSM, prognosis was compared between groups according to several CCI cutoff values. No significant differences in disease-free survival or breast cancer-specific overall survival (OS) were observed according to the CCI score. Similarly, no significant differences in OS were observed between the high- and low-CCI groups at CCI cutoff values of 1 and 2. However, at a CCI cutoff value of 3, OS was significantly worse in patients with higher CCI scores. CONCLUSION: Among patients with breast cancer, those with CCI scores ≥ 3 often experience mortality due to diseases other than breast cancer.