2.2 Study selection and inclusion criteria
In this systematic review, original studies were selected when conformed
to the established inclusion criteria, as further stated subsequently:
(1) Publications using English language. (2) Data not received on animal
samples. (3) Observational studies. (4) Reports focusing on the
evaluation of PD-L1 in clinicopathological parameters and survival
outcomes. (5) Studies supplying existing odds ratio (OR) or hazard ratio
(HR) along with 95% CI , or else, adequate data to calculated. (6)
Participants not undergoing any radiotherapy/chemotherapy before
surgical resection.
Two researchers were responsible for independently screening titles and
abstracts, and then deeply evaluated the retrieved articles in the
primal search. The articles were discarded that were performed in
nonhuman subjects, editorials, duplicates, expert comments, review in
various forms, meta-analysis, clinical trials.