Weekday Surgery Associated With Short-Term Outcomes in Patients With Colorectal Cancers.

Introduction: The "weekday effect" on elective surgery remains controversial. We aimed to examine the association between the day of surgery and short-term outcomes after elective surgery for stage I-III colorectal cancer (CRC).

Methods: We performed a multicenter retrospective analysis of 2574 patients who underwent primary colorectal resection for CRC between January 2017 and December 2019 at 15 institutions belonging to the Hiroshima Surgical Study Group of Clinical Oncology. Patients were divided into two groups according to the day of surgery: Friday and non-Friday (Monday to Thursday). After propensity score matching (PSM), we compared 30-day mortality and postoperative outcomes.

Results: Out of the total, 368 patients underwent surgery on Fridays, and the remaining 2206 underwent surgery on non-Fridays. The overall mortality rate was 0.04% (n = 1). In 1685 patients with colon cancer, the proportion of American Society of Anesthesiologists scores was significantly lower in the Friday group than in the non-Friday group before PSM. After PSM of patient, tumor, and operative characteristics, operative time was slightly more prolonged and blood loss was slightly greater in the Friday group; however, these differences were not clinically meaningful. In the 889 patients with rectal cancer, the proportion of patients with abnormal respiratory patterns was significantly lower in the Friday group than in the non-Friday group before PSM. After PSM, the Friday group had a higher incidence of morbidity (≥ Clavien-Dindo 3a), higher incidence of digestive complications, and prolonged postoperative hospital stay.

Conclusions: The results may be useful in determining the day of the week for CRC surgery, which requires more advanced techniques and higher skills.