Relation of surgeon and hospital volume to processes and outcomes of colorectal cancer surgery.

BACKGROUND: Greater hospital volume has been associated with lower mortality after colorectal cancer surgery. The contribution of surgeon volume to processes and outcomes of care is less well understood. We assessed the relation of surgeon and hospital volume to postoperative and overall mortality, colostomy rates, and use of adjuvant radiation therapy.

METHODS: From the California Cancer Registry, we studied 28,644 patients who underwent surgical resection of stage I to III colorectal cancer during 1996 to 1999 and were followed up to 6 years after surgery to assess 30-day postoperative mortality, overall long-term mortality, permanent colostomy, and use of adjuvant radiation therapy.

RESULTS: Across decreasing quartiles of hospital and surgeon volume, 30-day postoperative mortality ranged from 2.7% to 4.2% (P < 0.001). Adjusting for age, stage, comorbidity, and median income among patients with colorectal cancer who survived at least 30 days, patients in the lowest quartile of surgeon volume had a higher adjusted overall mortality rate than those in the highest quartile (hazard ratio, 1.16; 95% confidence interval, 1.09-1.24), as did patients in the lowest quartile of hospital volume relative to those treated in the highest quartile (hazard ratio, 1.11; 95% confidence interval, 1.05-1.19). For rectal cancer, adjusted colostomy rates were significantly higher for low-volume surgeons, and the use of adjuvant radiation therapy was significantly lower for low-volume hospitals.

CONCLUSIONS: Greater surgeon and hospital volumes were associated with improved outcomes for patients undergoing surgery for colorectal cancer. Further study of processes that led to these differences may improve the quality of colorectal cancer care.