Purpose: This study aimed to assess the effect of comorbidities on prognosis using the Age-adjusted Charlson Comorbidity Index (ACCI) among the elderly with breast cancer (BC).
Methods: This study included 745 patients divided into two groups following the ACCI score (≤ 3 vs > 3). Multivariate logistic regression analysis was conducted for all kinds of outcomes, including BC-specific death (BCSD) and non-breast cancer-specific death (NBCSD). The Kaplan–Meier curves were plotted, and survival analysis was conducted for disease-free survival (DFS), overall survival (OS), BC-specific survival (BCSS), and non-BCSS (NBCSS).
Results: A significantly higher NBCSD was found in the high-score (ACCI > 3) group than in the low-score (ACCI < 3) group (p = 0.032). The multivariate logistic regression analysis revealed ACCI score as an independent affecting factor for all-cause death (hazard ratio [HR] = 0.42, 95% confidence interval [CI]: 0.22– 0.83, p = 0.012) and NBCSD (HR = 0.41, 95% CI: 0.20– 0.87, p = 0.020). The Kaplan–Meier curves revealed statistical differences only in NBCSS between the two groups (p = 0.039). Subgroup analysis revealed a worse prognosis in the high-score group for OS and NBCSS among hormone receptor-positive participants and those who without undergoing axillary dissection or receiving chemotherapy (all p < 0.05). Multivariate Cox regression analysis revealed ACCI as an independent prognostic predictor for OS (HR = 2.18, 95% CI: 1.22– 3.92, p = 0.009) and NBCSS (HR = 2.04, 95% CI: 1.02– 4.08, p = 0.044).
Conclusion: ACCI was indeed an effective indicator of the effects of comorbidities on survival among elderly patients with BC. However, the co-effect from age and comorbidities was not significant enough on cancer-specific prognosis, although it exerted a significant effect on treatments received.
Keywords: comorbidity, elderly, breast cancer, Age-adjusted Charlson Comorbidity Index, prognosis