Subgroup analysis for the prognostic value of Oct-4 expression in patients with NSCLC stratified by (A) statistical analysis, (B) the origins of patients, (C) positive-staining sites and (D) histological subtypes. AC, adenocarcinoma; CI, confidence interval; HR, hazard ratio; NSCLC, non-small cell lung cancer; Oct-4, octamer-binding transcription factor 4; SCC, squamous cell carcinoma.