The data of the German prospective multicenter study of the Study Group for Colo-Rectal Carcinoma (SGCRC) were analyzed by uni- and multivariate methods with regard to surgeon-related prognostic factors. The parameters were frequency of intraoperative local tumor spillage, surgical volume, and department and surgical quality group. The results obtained from the data of the SGCRC implicate consequences for analyses and comparisons of therapy results and studies on adjuvant therapy in colon and rectal cancer. All identified prognostic factors must be regarded and respectively considered in study designs. Colon and rectal cancer patients must also be distinguished and separate analyses are necessary for these.