Lessons learnt from scoring adjuvant colon cancer trials and meta-analyses using the ESMO-Magnitude of Clinical Benefit Scale V.1.1

BACKGROUND: Form 1 of the European Society for Medical Oncology-Magnitude of Clinical Benefit Scale (ESMO-MCBS) serves to grade therapies with curative intent. Hitherto only few trials with curative intent have been field tested using form 1. We aimed to evaluate the applicability of the scale and to assess the reasonableness of the generated scores in early colon cancer, in order to identify shortcomings that may be rectified in future amendments. METHODS: Adjuvant studies were identified in PubMed, Food and Drug Administration and European Medicines Agency registration sites, as well as ESMO and National Comprehensive Cancer Network guidelines. Studies meeting inclusion criteria were graded using form 1 of the ESMO-MCBS V.1.1 and field tested by ESMO Colorectal Cancer Faculty. Shortcomings of the scale were identified and evaluated. RESULTS: Eighteen of 57 trials and 7 out of 14 meta-analyses identified met criteria for ESMO-MCBS V.1.1 grading. In stage III colon cancer, randomised clinical trials and meta-analyses of modulated 5-fluorouracil (5-FU) based chemotherapy versus surgery scored ESMO-MCBS grade A and randomised controlled trials (RCTs) and meta-analyses comprising oxaliplatin added to this 5-FU backbone showed a more modest additional overall survival benefit (grade A and B). For stage II colon cancer, the findings are less consistent. The fluoropyrimidine trials in stage II were graded ‘no evaluable benefit’ but the most recent meta-analysis demonstrated a 5.4% survival advantage after 8 years follow-up (grade A). RCTs and a meta-analysis adding oxaliplatin demonstrated no added benefit. Exploratory toxicity evaluation and annotation was problematic given inconsistent toxicity reporting and limited results of late toxicity. Field testers (n=37) reviewed the scores, 25 confirmed their reasonableness, 12 found them mostly reasonable. Moreover, they identified the inability of crediting improved convenience in non-inferiority trials as a shortcoming. CONCLUSION: Form 1 of the ESMO-MCBS V.1.1 provided very reasonable grading for adjuvant colon cancer studies.