Hospital surgical volume and 3-year mortality in severe prognosis cancers: A population-based study using cancer registry data

BACKGROUND: The impact of hospital surgical volume on long-term mortality has not been well assessed in Japan, especially for esophageal, biliary tract, and pancreatic cancer, although these three cancers need a high-level of medical technical skill. The purpose of this study was to examine associations between hospital surgical volume and 3-year mortality for these severe prognosis cancer patients. METHODS: Patients who received curative surgery for esophageal, biliary tract, and pancreatic cancers were analyzed using Osaka Cancer Registry data from 2006-2013. Hospital surgical volume was categorized into tertiles (high/middle/low) according to the average annual number of curative surgeries per hospital for each cancer. Three-year survivals were calculated using the Kaplan-Meier method. Hazard ratios (HRs) of 3-year mortality were calculated using Cox proportional hazard models, adjusting for patient characteristics. RESULTS: Three-year survival was higher with increased hospital surgical volume for all three cancers, but the relative importance of volume varied across sites. After adjustment for all confounding factors, HRs (95% Confidence interval [CI]) in middle- and low-volume hospitals were 1.34 (95% CI, 1.14-1.58) and 1.57 (95% CI, 1.33-1.86) for esophageal cancer; 1.39 (95% CI, 1.15-1.67) and 1.57 (95% CI, 1.30-1.89) for biliary tract cancer; 1.38 (95% CI, 1.16-1.63) and 1.90 (1.60-2.25) for pancreatic cancer, respectively. In particular localized pancreatic cancer, the impact of hospital surgical volume on 3-year mortality was strong (HRs: 2.66 [95% CI, 1.61-4.38]). CONCLUSION: We suggest that patients who require curative surgery for esophageal, biliary tract, and pancreatic cancer may benefit from referral to high-volume hospitals.