Correlation between schistosomiasis and CD8+ T cell and stromal PD-L1 as well as the different prognostic role of CD8+ T cell and PD-L1 in schistosomal-associated colorectal cancer and non-schistosomal-associated colorectal cancer

Background The effect of schistosomiasis on CD8+ T cells and then on PD-L1 expression was unknown, and the utility of CD8+ TILs as a biomarker for schistosomal-associated colorectal cancer (SCRC) rarely has been reported. Methods Three hundred thirty-eight patients with colorectal cancer (CRC) were enrolled. Immunohistochemical analysis was conducted to evaluate the expression of PD-L1 and the infiltration of CD8+ T cells. Results In the total cohort, the results showed that CD8 + TIL density was positively correlated with tumoral ( p = 0.0001) and stromal PD-L1 expression ( p = 0.0102). But there were no correlation between schistosomiasis and CD8+ TILs and PD-L1. Furthermore, CD8 + TIL density ( p = 0.010), schistosomiasis ( p = 0.042) were independent predictive factors for overall survival (OS). Stromal PD-L1 (sPD-L1) was correlated with OS ( p = 0.046 ), but it was not an independent predictor. In patients without schistosomiasis, CD8 + T cells ( p = 0.002) and sPD-L1 ( p = 0.005) were associated with better OS. In patients with schistosomiasis, CD8 + T cells were independent prognosis factor ( p = 0.045). Conclusions The study showed that CD8+ TILs was an independent predictive factor for OS in CRC and SCRC patients. The expression of PD-L1 was positively associated with CD8 + TILs density. There were no correlation between schistosomiasis and CD8 + TILs and PD-L1. Stromal PD-L1 but not tPD-L1 was significantly associated with OS, whereas it was not an independent prognostic factor.