What is a clinically meaningful survival benefit in refractory metastatic colorectal cancer?

Assessment of the clinical benefit of cancer treatments can be highly subjective, influenced by both perspective and context. Such assessments are required in regulatory and policy decision-making, but consistency between jurisdictions is often lacking. Clear and consistent standards for determining when a treatment offers a meaningful benefit, relative to the current standard of care, can help to address issues of equity and transparency in health technology assessment. For metastatic colorectal cancer (MCRC), no standardized Canadian definition of clinically meaningful benefit has yet been proposed. Colorectal Cancer Canada therefore convened a group of medical oncologists expert in colorectal cancer to review the literature about clinical significance. The resulting consensus is intended to apply to any therapeutic agent being considered in the setting of chemotherapy-refractory MCRC. It was agreed that overall survival is the appropriate measure of clinical efficacy in chemorefractory MCRC. As quantitative targets for efficacy, an improvement of 2 months or more in median overall survival or a hazard ratio for survival of 0.75 or lower (or both) are proposed as the threshold for clinically meaningful benefit. That threshold could be influenced by a treatment’s effect on quality of life. Treatment toxicity is also relevant to the assessment of clinical benefit in this setting, specifically when significant differences in treatment tolerability are evident.