Prognostic Significance of PD-L1 Expression in Stage 4 Non-Small-Cell Lung Cancer

Abstract

Objectives: Since lung cancer is the most deadly cancer in the world, developments regarding immune control points and molecules affecting these points have increased. The positive effects of immunotherapy treatments affecting the PD-1/programmed death receptor ligand-1(PD-L1) immune checkpoint on prognosis have drawn attention to these immunocheckpoints. While immunotherapy studies developed for the PD-1 pathway continue rapidly, the aim of this study is to investigate whether PD-L1 level can be used as a prognostic marker in non-small-cell lung cancer independent of immunotherapy. Methods: 115 patients admitted to our center between January 01, 2016, and January 01, 2018 and diagnosed with non-small-cell lung cancer were retrospectively analyzed. The files of all patients were scanned in detail and their pathological data were confirmed. Demographic data of the patients included in the study, pathological diagnosis methods, treatment information about the disease, and past medical histories of the patients were recorded with reference to the hospital database. Results: The patients with PD-L1 <50% were considered the negative group (NG), and the group with a PD-L1 value of 50% or more was considered the positive group (PG). There were 27 patients in the NG and 11 patients in the PG. It was determined that 21 (67.8%) of 27 NG patients and 3 (21.3%) of 11 PG patients died. In total, 24 (73.2%) of 38 patients were found to have died. While the mean survival in the NG was 10.81 months, the mean survival in the PG was 28.54 months. Mean survival in the PG was statistically significant (p=0.046). Conclusion: PD-L1 expression was found to be a positive predictive value in Stage 4 non-small-cell lung cancer. Our study differs from other studies in that it excluded epidermal growth factor receptor, anaplastic lymphoma kinase, and ROS mutations. To determine the relationship of PD-L1 with prognosis more clearly, there is a need for randomized, prospective studies with larger patient groups that exclude target mutations and are independent of immunotherapy and targeted therapies.