Impact of time-to-surgery on survival outcomes in Korean breast cancer patients: A nationwide population-based cohort study.

Abstract

581 Background: The increasing incidence of breast cancer and the resulting surgical workload in South Korea have led to concerns regarding surgical delays. While the clinical impact of time-to-surgery (TTS) remains debated, defining an optimal threshold is crucial for health policy and patient outcomes. This study aimed to investigate the impact of TTS on overall survival (OS), disease-free survival (DFS), and breast cancer-specific survival (BCSS) using nationwide claims data. Methods: This study utilized a merged dataset from the National Health Insurance Service and Korean Statistical Information Service database. We identified 11,683 women newly diagnosed with Stage I-III primary breast cancer in 2016, excluding prior history or concurrent malignancies. TTS was defined as the interval from breast cancer diagnosis to the definitive surgical procedure. To determine the optimal clinical cutoff, the Contal and O’Quigley method was applied. Multivariable Cox proportional hazards models were used for OS. To account for competing risks, the Fine-Gray subdistribution hazard model was employed for DFS and BCSS, with non-breast cancer death treated as a competing event. Covariates included physical activity, type and region of institution, systemic treatments, income decile, and Charlson Comorbidity Index (CCI) score. Results: Initial analysis using 30-day and 60-day thresholds showed significant differences in survival outcomes. The Contal and O’Quigley method identified 68 days as the optimal cutoff for TTS. Patients with TTS > 68 days exhibited significantly worse OS compared to those with TTS ≤ 68 days (adjusted Hazard Ratio [HR], 3.396; 95% CI, 2.402-4.802; p < 0.001). In the competing risk regression, TTS > 68 days was associated with inferior DFS (adjusted subdistribution HR [sHR], 1.496; p = 0.001) and BCSS (adjusted sHR, 5.868; p < 0.001). The negative impact of delayed surgery remained consistent across various subgroups regardless of income level or comorbid status. Conclusions: Delays in surgery exceeding 68 days are significantly associated with poorer survival outcomes in Korean breast cancer patients. These findings suggest that every effort should be made to perform surgery within 68 days of diagnosis to optimize long-term prognosis. Clinicians should prioritize streamlining the diagnostic-to-treatment pathway to minimize surgical wait times.