The Association of Programmed Death-Ligand 1 Expression with Clinicopathological Features, Lymph Node Metastasis and Survival Prognosis in Patients with Colorectal Carcinoma

Colorectal carcinoma (CRC) is one of the most frequently encountered neoplasms with high morbidity and mortality. Activation of the programmed death protein 1/ programmed death ligand 1 (PD-1/PD-L1) pathway results in tumor immune evasion by suppressing the activity of T cells. The correlation of PD-L1 with clinicopathological features, lymph node metastasis and prognosis is less clear. The aim of present work was to study the relationship between PD-L1 and clinicopathological features and prognosis of CRC patients. Three hundred and eighty-six patients were included in this study. Serum PD-L1 was measured by ELISA, and PD-L1 on tumor cells was evaluated by immunohistochemistry. Pretreatment levels of PD-L1 were significantly elevated in CRC patient sera compared to healthy donors ( P <0.001). The mean value of PD-L1 in healthy donors, CRC with non-lymph node metastasis, and CRC with lymph node metastasis were 229.22±54.7pg/mL, 400.77±66.3pg/ mL, and 414.29±59.1pg/mL, respectively. The positive rate of PD-L1 in metastatic lymph node was higher than in primary tumor ( P <0.001). PD-L1 negative patients had higher five-year survival rate than PD-L1 positive patients (68.57% vs 46.98%, P =0.012). The univariate analysis indicated that tumor differentiation, lymph node metastasis, and PD-L1 were correlated with five-year survival rate of CRC patients (all P < 0.018). Multivariate analysis showed that lymph node metastasis and PD-L1 were independent prognostic factors (all P < 0.008). Our study demonstrates that PD-L1 negative patients have better five-year survival rate, and PD-L1 and lymph node metastasis are independent prognostic factors in CRC patients.