Influence of volume and specialization on survival following surgery for colorectal cancer

Background: Previous studies have shown that significant surgeon-related differences in survival exist following surgery for colorectal cancer. It is not clear whether these differences were due to differences in caseload or degree of specialization. Methods. Outcome in 3200 patients who underwent resection for colorectal cancer between 1991 and 1994 was analysed on the basis of caseload and degree of specialization of individual surgeons. Five-year survival rates, and the corresponding hazard ratios adjusted for case mix, were calculated. Results: Cancer-specific survival rate at 5 years following curative resection varied among surgeons from 53.4 to 84.6 per cent; the adjusted hazard ratios varied from 0.48 to 1.55. Cancer-specific survival rate at 5 years following curative resection was 70.2, 62.0 and 65.9 per cent for surgeons with a high, medium and low case volume respectively. There were no consistent differences in the adjusted hazard ratios by volume. Cancer-specific survival rate at 5 years following curative resection was 72.7 per cent for those treated by specialists and 63.8 per cent for those treated by non-specialists; the adjusted hazard ratio for non-specialists was 1.35 (95 per cent confidence interval 1.13 to 1.62; P = 0.001). Conclusion. The differences in outcome following apparently curative resection for colorectal cancer among surgeons appear to reflect the degree of specialization rather than case volume. It is likely that increased specialization will lead to further improvements in survival.