Treatment interval in curative treatment of colon cancer and its impact on (cancer-free) survival in high-risk and non-high-risk patients

INTRODUCTION: Implementation of prehabilitation for patients undergoing surgical treatment for colon cancer has proven effective in reducing the risk of postoperative complications. Currently the recommended maximal treatment interval has limited span for implementation of a prehabilitation program. The aim of the current study was to determine the association between advised treatment interval and (cancer-free) survival, while stratifying for the risk of postoperative complications. MATERIALS AND METHODS: This retrospective multicenter study included patients who underwent elective surgical treatment for colon cancer between 2010 and 2016. Patients were stratified based on risk of postoperative complications (high-risk and non-high-risk). Treatment interval was defined as time between diagnosis and surgery, divided into three categories (≤35 days, 36-49 days, and > 49 days). Primary endpoints were overall survival and cancer-free survival, assessed by multivariate Cox proportional hazard regression analysis. RESULTS: A total of 3376 patients were included, of whom 60% were considered non-high-risk and 40% high-risk, with a median age of 72 years (IQR 64-78). Of the included patients, 862 (26%) had tumor stage I, 1353 (40%) had tumor stage II, and 1160 (34%) had tumor stage III colon cancer. Treatment interval was not associated with cancer-free survival (36-49 days [non-high-risk p = 0.77; high-risk p = 0.56] or > 49 days [non-high-risk p = 0.46; high-risk p = 0.13]). A treatment interval > 49 days was associated with poorer five-year overall survival in non-high-risk patients (HR = 1.35, p < 0.05), but not in high-risk patients (p = 0.69). A treatment interval of 36-49 days was not associated with five-year overall survival (non-high-risk p = 0.24; high-risk p = 0.98). DISCUSSION: Extending the treatment interval in curative treatment of colon cancer up to 49 days appears safe for both high-risk and non-high-risk patients. For high-risk patients, the expected benefits of longer treatment interval including prehabilitation should be balanced with the medical urgency to operate.