Treatment interval in curative treatment of colon cancer, does it impact (cancer free) survival? A non-inferiority analysis.

BACKGROUND: In treatment of colon cancer, strict waiting-time targets are enforced, leaving professionals no room to lengthen treatment intervals when advisable, for instance to optimise a patient's health status by means of prehabilitation. Good quality studies supporting these targets are lacking. With this study we aim to establish whether a prolonged treatment interval is associated with a clinically relevant deterioration in overall and cancer free survival.

METHODS: This retrospective multicenter non-inferiority study includes all consecutive patients who underwent elective oncological resection of a biopsy-proven primary non-metastatic colon carcinoma between 2010 and 2016 in six hospitals in the Southern Netherlands. Treatment interval was defined as time between diagnosis and surgical treatment. Cut-off points for treatment interval were ≤35 days and ≤49 days.

FINDINGS: 3376 patients were included. Cancer recurred in 505 patients (15.0%) For cancer free survival, a treatment interval >35 days and >49 days was non-inferior to a treatment interval ≤35 days. Results for overall survival were inconclusive, but no association was found.

CONCLUSION: For cancer free survival, a prolonged treatment interval, even over 49 days, is non-inferior to the currently set waiting-time target of ≤35 days. Therefore, the waiting-time targets set as fundamental objective in current treatment guidelines should become directional instead of strict targets.