Programmed death-ligand 1 expression and overall survival in Thai patients with gastric cancer

Abstract

Abstract Background Programmed death-ligand 1 (PD-L1) expression has now been implicated in gastric cancer (GC). However, data on PD-L1 expression in GC patients receiving standard-of-care are limited. Therefore, this study was conducted to determine the impact of clinicopathological characteristics on PD-L1 expression and its association with overall survival in Thai patients with GC. Methods We retrospectively collected clinical data on 268 patients with GC from Chiang Mai University Hospital between January 2018 to December 2021. PD-L1 expression was assayed by immunohistochemistry staining using the Dako 22C3 pharmDx. PD-L1 positivity was defined as the combined positive score (CPS) ≥ 1. Results The rate of PD-L1 positivity in Thai patients with GC was 22%. PD-L1 expression had no statistical correlation with gender, tumor location, diameter, pTNM stage, Lauren classification, or lymphatic and vascular invasion. However, PD-L1 positivity was significantly higher in patients younger than 55 than those older than 55 (32.6% vs. 16.5%, p = 0.035). In addition, PD-L1 positivity was observed more frequently in GC with metastases than without (28.6% vs. 20.8%, p = 0.694). Moreover, patients with PD-L1 positive had a significantly shorter median overall survival than those with PD-L1 negative (32.7 vs. 41.6 months, p = 0.042). Conclusions PD-L1 expression is evident in one-fourth of Thai patients with GC. The expression of PD-L1 in GC patients has been associated with young age, short survival, and metastases, although unrelated to the tumor stage. Therefore, testing GC tumors for PD-L1 expression is recommended to provide a therapeutic advantage in Thai patients.