Surgical volume and long-term survival following surgery for colorectal cancer in the Veterans Affairs Health-Care System

Abstract

Objective: The objective of this study was to examine the relationship between hospital surgical volume and long-term survival in patients with a new diagnosis of colorectal cancer who underwent surgical resection during fiscal years 1991-2000 in the Veterans Affairs (VA) health-care system.

Methods: This research was a cohort study of patients admitted to all VA hospitals with a new diagnosis of colorectal cancer who underwent surgical resection between October 1990 and September 2000 and followed through September 2001. Overall 5-yr cumulative survival was calculated from Kaplan-Meier estimates, while adjusted risk of death was estimated using a Cox proportional hazards model. Adjustment was made for differences in patient characteristics including comorbidity, receipt of therapy, and year of surgery.

Results: We identified 34,888 individuals with a new diagnosis of colorectal cancer in VA hospitals during fiscal years 1991-2000, of whom 22,633 (65%) underwent surgical resection. The majority (98.5%) were men, the mean age was 68 yr, and the two largest race/ethnic groups were whites (75%) and blacks (17%). The 5-yr cumulative survival was greater among those who received surgery in high surgical volume hospitals as defined by 25 or more procedures per year (52.1%) than among those who received surgery in low volume hospitals (48.3%). After adjusting for differences in patient characteristics, comorbidity, receipt of adjuvant therapy, and year of surgery, we found 7% and 11% increases in 5-yr survival for patients with colon and rectal cancers, respectively, who underwent surgical resection in high volume hospitals compared with those who had surgery in low volume hospitals.

Conclusions: Greater hospital surgical volume is an independent predictor of prolonged long-term survival following surgery for both colon and rectal cancer in the VA health-care system. The volume-long-term mortality relationship is greater for rectal than for colon cancer patients, perhaps reflecting the fact that surgery for rectal cancer is more technically demanding. Future studies are needed to discover what aspects of clinical management explain these differences.