PD-L1 and ALK expressions in stages III and IV colorectal cancer and their correlation with clinicopathological features

Colorectal cancer (CRC) is a type of cancer with a high recurrence rate. Studies are in the progress to identify effective treatments for CRC patients. We aimed to compare the expression of programmed death-ligand 1 (PD-L1) and anaplastic lymphoma kinase (ALK) in stages III and IV CRC patients and evaluate the clinicopathological significance associated with their expression. A total of 169 stages III and IV CRC specimens was tested for ALK (D5F3) and PD-L1 (SP142 and SP263) expression using immunohistochemistry on formalin-fixed paraffin-embedded specimens. Clinicopathological characteristics were obtained through a review of the medical records and hematoxylin and eosin slides. Expression of PD-L1 SP142 and PD-L1 SP263 was detected in 17.8% and 28.4% of CRC patients, respectively. ALK D5F3 expression was detected in 4 cases. PD-L1 SP142 expression was significantly correlated with tumor site and serum carcinoembryonic antigen (CEA) level. PD-L1 SP263 expression was associated with serum tumor marker level and tumor-infiltrating lymphocytes. In univariate analysis, PD-L1 expression was correlated with shorter survival in CRC patients. PD-L1 SP263 expression was an independent indicator of shorter survival in multivariate analysis. PD-L1 expression was associated with poor prognostic factors, including shorter survival. Further investigation is needed to understand the mechanisms of the association between PD-L1 expression and unfavorable CRC prognosis.