Weekday of gastrectomy for cancer in relation to mortality and oncological outcomes - A Dutch population-based cohort study

Background: Some studies demonstrate that high-complex surgeries performed later in the week are associated with higher postoperative mortality and worse long-term survival. The aim of this cohort study was to determine whether weekday influences outcomes in patients undergoing gastrectomy for cancer. Methods: All patients who underwent a curative gastrectomy for cancer (2006-2014) were selected from the nationwide population-based Netherlands Cancer Registry. Weekday was analyzed as categorized (Monday-Tuesday versus Wednesday-Friday) and discrete variable (Monday-Friday). The influence of weekday on postoperative 30- and 90-day mortality, and oncological outcomes (lymph node yield, radicality rate and overall survival) was assessed with multivariable logistic and Cox regression analyses. Results: A total of 3.776 patients were included with a median overall survival of 26.7 months [range 0-120]. The 30- and 90-day mortality were 5% and 8% respectively, median lymph node yield was 13 [range 0-87], and radicality rate was 87%. In multivariable analysis, no influence of weekday was found on postoperative mortality (p > 0.05), on R0 resection rates (p > 0.05), nor on overall survival (Monday-Friday, HR 1.03, 95%CI 1.01-1.04, p = 0.111; Wednesday-Friday vs. Monday-Tuesday, HR 1.05, 95%CI 0.96-1.14, p = 0.307). The lymph node yield was significantly lower later in the week compared to earlier (Monday-Friday, OR 0.94, 95%CI 0.89-0.99, p = 0.013; Wednesday-Friday vs. Monday-Tuesday OR 0.83, 95%CI 0.71-0.96, p = 0.010), which was most apparent in recent years of surgery. Conclusion: Gastric cancer surgery can be performed safely throughout the week regarding postoperative mortality, radicality and overall survival. A point of concern is a reduced lymph node yield later in the week.