Clinical Importance of CD200 Expression in Colorectal Liver Metastasis.

BACKGROUND Approximately 30% of patients diagnosed with colorectal cancer (CRC) develop liver metastases. We evaluated the role of CD200, a potent immunosuppressive molecule, in colorectal liver metastases (CRLM). METHODS We examined 110 patients who underwent curative liver resection for CRLM at our institution between 2000 and 2016. Based on the results of immunohistochemical analysis, the patients were divided into high-CD200 (n = 47) and low-CD200 (n = 63) expression groups. The relationships between CD200 expression and various clinicopathological outcomes were investigated. RESULTS The overall survival (OS) of patients in the high-CD200 group was significantly worse than that in the low-CD200 group (p = 0.009). Multivariate analysis showed that the independent prognostic factors in CRLM were maximum tumor size > 30 mm (p = 0.002), preoperative carcinoembryonic antigen level > 20 ng/mL (p < 0.001), primary CRC N2-3 (p = 0.049), and high-CD200 expression (p = 0.004). Furthermore, CD4+, CD8+, and CD45RO+ tumor-infiltrating lymphocytes in CRLM were significantly higher in the low-CD200 group than in the high-CD200 group (p = 0.005, p = 0.001, and p < 0.001, respectively). In addition, patients who had received preoperative chemotherapy had higher CD200 expression than those who had not received preoperative chemotherapy, and OS was significantly worse in patients in the high-CD200 group who had received preoperative chemotherapy. CONCLUSIONS CD200 expression was an independent prognostic factor in CRLM. CD200 may play a critical role in tumor immunity in CRLM, and can therefore be used as a potential therapeutic target in CRLM.