The Immunoscore system predicts prognosis after liver metastasectomy in colorectal cancer liver metastases

Background The Immunoscore was initially established to evaluate the prognosis of stage I/II/III colorectal cancer patients. However, the feasibility of the Immunoscore for the prognosis of colorectal cancer liver metastases (CRCLM) has not been reported. Methods Liver metastases in 249 CRCLM patients were retrospectively analyzed. The Immunoscore was assessed according to the counts and densities of CD3+ and CD8+ T cells in the central- and peritumoral areas by immunohistochemistry. The prognostic role of the Immunoscore for relapse–free survival (RFS) and overall survival (OS) was analyzed with Kaplan–Meier curves and Cox multivariate models, and confirmed via an internal validation. Receiver operating characteristic (ROC) curves were plotted to compare the prognostic values of the Immunoscore and the clinical risk score (CRS) system. Results CRCLM patients with high Immunoscores (> 2) had significantly longer RFS [median RFS (95% confidence interval; 95% CI) 21.4 (7.8–35.1) vs. 8.7 (6.8–10.5) months, P < 0.001] and OS [median OS (95% CI): not reached vs. 28.7 (23.2–34.2) months, P < 0.001] than those with low Immunoscores (≤ 2). After stratification by CRS, the Immunoscore retained a statistically significant prognostic value for OS. The areas under the ROC curves (AUROCs) of the Immunoscore and the CRS system for RFS were 0.711 [95% CI 0.642–0.781] and 0.675[95% CI 0.601–0.749] ( P = 0.492), whereas the AUROC of the Immunoscore system for OS was larger than that of the CRS system [0.759 (95% CI 0.699–0.818) vs. 0.660 (95% CI 0.592–0.727); P = 0.029]. Conclusions The Immunoscore of liver metastases can be applied to predict the prognosis of CRCLM patients following liver resection.