Weekday-dependent long-term outcomes in gastrointestinal cancer surgery: a german population-based retrospective cohort study.

This is the first study investigating the influence of the WOS on long-term survival in Germany. Our findings indicate that, in the German healthcare system, patients undergoing colorectal cancer surgery on Mondays have more postoperative complications and, therefore, require significantly more re-operations, ultimately lowering OS. This surprising finding appears to reflect an attempt to schedule patients with higher postoperative risk earlier in the week as well as semi-elective patients admitted on weekends scheduled for surgery on the next Monday.