Weekday of cancer surgery in relation to prognosis

Background Later weekday of surgery seems to affect the prognosis adversely in oesophageal cancer, whereas any such influence on other cancer sites is unknown. This study aimed to test whether weekday of surgery influenced prognosis following commonly performed cancer operations. Methods This nationwide Swedish population‐based cohort study from 1997 to 2014 analysed weekday of elective surgery for ten major cancers in relation to disease‐specific and all‐cause mortality. Cox regression provided hazard ratios with 95 per cent confidence intervals, adjusted for the co‐variables age, sex, co‐morbidity, hospital volume, calendar year and tumour stage. Results A total of 228 927 patients were included. Later weekday of surgery (Thursdays and, even more so, Fridays) was associated with increased mortality rates for gastrointestinal cancers. Adjusted hazard ratios for disease‐specific mortality, comparing surgery on Friday with that on Monday, were 1·57 (95 per cent c.i. 1·31 to 1·88) for oesophagogastric cancer, 1·49 (1·17 to 1·88) for liver/pancreatic/biliary cancer and 1·53 (1·44 to 1·63) for colorectal cancer. Excluding mortality during the initial 90 days of surgery made little difference to these findings, and all‐cause mortality was similar to disease‐specific mortality. The associations were similar in analyses stratified for co‐variables. No consistent associations were found between weekday of surgery and prognosis for cancer of the head and neck, lung, thyroid, breast, kidney/bladder, prostate or ovary/uterus. Conclusion Later weekday of surgery (Thursday or Friday) seems to influence the prognosis adversely for cancers of the gastrointestinal tract.