A novel score system for predicting conversion to no evidence of Disease (C-NED) in initially unresectable colorectal cancer liver metastases

An estimated 70-80% of cases of colorectal cancer liver metastasis (CRLM) are defined as initially unresectable. "Converting" to no evidence of disease (NED) status may prolong survival. The current study aimed to develop a novel scoring system that predicts the conversion outcome for initially unresectable CRLM. A total of 215 consecutive CRLM patients who received first-line systemic therapy from December 2012 to January 2020 at Sun Yat-sen University Cancer Center were enrolled in the internal cohort. Forty CRLM patients from the database of the Chinese Colorectal Cancer Multidisciplinary Team Alliance were enrolled in the external cohort. A logistic regression model was applied to identify risk factors associated with the conversion outcome. The tumor-to-liver volume ratio (TLVR) was calculated as the total tumor volume divided by the total liver volume, and its cutoff value was 0.23. Three predictors of conversion failure were identified in the internal cohort and incorporated into the C-NED score: poor tumor differentiation (1 point), number of liver metastases > 8 (1 point) and TLVR >= 0.23 (1 point). The conversion rate was significantly negatively associated with the C-NED score (P < 0.001). The C-indexes of the C-NED score for predicting successful conversion outcome in the internal cohort and external cohort were 0.734 (95% confidence interval (CI), 0.668-0.800) and 0.736 (95% CIs, 0.566-0.907), respectively. Median progressionfree survival (PFS) time (P = 0.001) and overall survival (OS) time (P = 0.003) were statistically significant different among different C-NED score groups. Our study demonstrated that the C-NED score is an effective scoring system that indicates the actual conversion probability for initially unresectable CRLM patients before treatment, which can serve as a tool that guides optimal first-line management strategies.