Background: Diabetes mellitus (DM) has been implicated in influencing the survival duration of patients with breast cancer. However, less is known about the impact of DM and other comorbidities on the breast cancer-specific survival (BCS) and overall survival (OS) outcomes of Asian patients with early-stage breast cancer.
Patients and methods: The characteristics of female patients with newly diagnosed, early-stage breast cancer were collected from the Taiwan Cancer Registry database for 2003-2004. DM status and other comorbidities were retrieved from Taiwan's National Health Insurance database. The BCS and OS times of patients according to DM status were estimated via the Kaplan-Meier method. Cox's proportional hazard model was used to estimate adjusted hazard ratios (HRs) for the effects of DM, comorbidities, and other risk factors on mortality.
Results: In total, 4,390 patients were identified and 341 (7.7%) presented with DM. The 5-year BCS and OS rates were significantly greater in DM patients than in non-DM patients (BCS, 85% versus 91%; OS, 79% versus 90%). Furthermore, after adjusting for clinicopathologic variables and comorbidities, DM remained an independent predictor of shorter BCS (adjusted HR, 1.53) and OS (adjusted HR, 1.71) times. Subgroup analyses also demonstrated a consistent prognostic influence of DM across different groups.
Conclusion: In Asian patients with early-stage breast cancer, DM is an independent predictor of lower BCS and OS rates, even after adjusting for other comorbidities. The integration of DM care as part of the continuum of care for early-stage breast cancer should be emphasized.