2.3 Data extraction and risk of bias assessment
For all enrolled studies, the following data were extracted by two
reviewers in regards of authors, publication years, county, number of
patients, anti-PD-L1 antibody, definitions of PD-L1 positivity, IHC
cutoffs, anatomic location, clinicopathological and prognostic
variables. The risk of bias in the individual studies was appraised
using the Reporting Recommendations for Tumour Marker Prognostic
(REMARK) guidelines13,which were composed of six
dimensions as summarised in Supplemental Fig.S2.