Data Extraction and Quality Assessment
Articles were screened independently by two researchers (RT and RM)
(according to Flowchart 1) and disagreements resolved through
discussions with other researchers. The extracted information included
author’s first name, study location, study type, type of marker
investigated, year of publication, type of survival analysis performed,
mean follow-up period, sample size, and a summary of the cut-off points
for the markers investigated. OS is usually the time length from the
beginning of medical treatment until outcome occurrence (death whether
or end of the follow-up period of the patient). PFS is the duration when
the treatment is started until tumor progresses or death happens for any
reason. In order to evaluate quality of the articles, two researchers
(MR and AH) independently used the checklist of Newcastle Ottawa Scale
(NOS) (35). The articles with a total score of ≥7 were considered as
high-quality.