Association of Traditional and new Surgical Wait Time Targets and Survival for Curative-intent Colorectal Cancer Surgery: A Population-based Cohort Study.

BACKGROUND Wait time (WT) to surgery is a common quality indicator for colorectal cancer (CRC). However, the definition of WT targets and its association with clinically relevant outcomes remains poorly defined. We assessed the association between WT to CRC surgery and overall survival (OS) for curative-intent surgery. METHODS We conducted a population-based retrospective cohort study of adults undergoing resection for stage I-III CRC (between 2007-2020), using health administrative data in Ontario, Canada. The exposure was WT, measured as the time from the decision to operate to surgery (in days). The outcome was OS, measured as time from surgery to death. Restricted cubic spline regression (RCS) examined the relationship between WT and hazards of death to identify meaningful WT thresholds. WT was then categorized as a) traditional WT target (≤ 28 days) or b) new data-informed target defined by RCS. Multivariable Cox proportional hazards explored the association between each WT target and the hazards of death after adjusting for confounders established a priori. RESULTS Of 35,533 patients, 27,102 (76.3%) underwent surgery within the traditional WT target. The median WT was 19 days (interquartile range 12-28). RCS revealed an inflection point around 45 days associated with increasing hazards of death. After adjusting for age, sex, co-morbidity, cancer site, stage, neo-adjuvant or adjuvant therapy, and year of surgery, having surgery within the traditional WT target (≤ 28 days) was not associated with OS (Hazards Ratio, [HR] 0.97; 95% confidence interval, [CI] 0.92-1.02). Having surgery within the new WT target (≤ 45 days) was independently associated with superior OS (HR 0.90, 95% CI 0.82-0.99). CONCLUSION In patients undergoing curative-intent resection for stage I-III CRC, having surgery within traditional WT target of 28 days was not associated with OS. However, having surgery within a WT target of 45 days was independently associated with superior OS. These data highlight the need to reconsider WT targets for quality monitoring by linking to clinically meaningful outcomes.