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

Abstract

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 severeprognosis cancer patients. Methods: Patients who received curative surgery for esophageal, biliary tract, and pancreatic cancers were analyzed using the 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 in middle- and low-volume hospitals were 1.34 (95% confidence interval [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 (95% CI, 1.60-2.25) for pancreatic cancer, respectively. In particular for localized pancreatic cancer, the impact of hospital surgical volume on 3-year mortality was strong (HR 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.