Expanding the ESMO-MCBS: integrating organ preservation into clinical benefit assessment in rectal cancer

We are writing to address the current application of the ESMO Magnitude of Clinical Benefit Scale (MCBS) in the specific context of rectal cancer. The MCBS is a widely adopted framework for assessing clinical benefit in oncology that has improved the comparability across trials by focusing on robust study endpoints, such as disease-free (DFS) and overall survival (OS),1 but it does not fully capture clinically meaningful benefits specific to rectal cancer—particularly organ preservation. We therefore believe there is an opportunity for further refinement of this scoring system, in light of evolving multimodal treatment strategies in rectal cancer.