BackgroundWith aging of the population, the number of colorectal cancer patients with impairment of activities of daily living (ADLs) has increased. The Barthel index is a validated tool for assessing functional levels of ADLs. In this retrospective study, we aimed to examine associations of Barthel index scores with recurrence and mortality after curative resection of colorectal cancer. MethodsWe retrospectively analyzed data of 815 consecutive patients who had undergone curative resection of stage I–III colorectal adenocarcinoma between January 2009 and December 2017. Preoperative functional levels of ADLs were assessed prospectively using the Barthel index (range, 0 to 100; higher scores indicate greater independence). Recurrence-free survival (RFS) and overall survival (OS) were compared according to Barthel index scores. The Cox proportional hazards model was used to calculate hazard ratios (HRs), controlling for potential confounders. ResultsOf the 815 patients, Barthel index scores were 40 or lower in 129 (16%), 41–85 in 110 (13%), and 86 or more in 576 (71%). In multivariable analyses adjusting for potential confounders including age and disease stage, scores of 85 or lower on the Barthel index were independently associated with shorter RFS (multivariable HR: 1.74, 95% confidence interval: 1.28–2.37, P<0.001) and OS (multivariable HR: 2.10, 95% confidence interval: 1.45–3.04, P<0.001). ConclusionsLower scores on the Barthel index are associated with shorter RFS and OS following resection of nonmetastatic colorectal cancer. Further studies are needed to establish treatment strategies for colorectal cancer patients with poor functional capacity.