Does surgeon or hospital volume influence outcome in dedicated colorectal units?-A Viennese perspective.

Objective: A clear relationship between higher surgeon volume and improved outcomes has not been convincingly established in rectal cancer surgery. The aim of this study was to evaluate the impact of individual surgeon's caseload and hospital volume on perioperative outcome.

Methods: We retrospectively analyzed 336 consecutive patients undergoing oncological resection for rectal cancer at two Viennese hospitals between 1 January 2015 and 31 December 2020. The effect of baseline characteristics as well as surgeons' caseloads (low volume: 0-5 cases per year, high volume > 5 cases per year) on postoperative complication rates (Clavien-Dindo Classification groups of < 3 and ≥ 3) were evaluated.

Results: No differences in baseline characteristics were found between centers in terms of sex, smoking status, or comorbidities of patients. Interestingly, only 14.7% of surgeons met the criteria to be classified as high-volume surgeons, while accounting for 66.3% of all operations. There was a significant difference in outcomes depending on the treating center in univariate and multivariate binary logistic regression analysis (odds ratio (OR) = 2.403, p = 0.008). Open surgery was associated with lower complication rates than minimally invasive approaches in univariate analysis (OR = 0.417, p = 0.003, 95%CI = 0.232-0.739) but not multivariate analysis. This indicated that the center's policy rather than surgeon volume or mode of surgery impact on postoperative outcomes.

Conclusion: Treating center standards impacted on outcome, while individual caseload of surgeons or mode of surgery did not independently affect complication rates in this analysis. The majority of rectal cancer resections are performed by a small number of surgeons in Viennese hospitals.