S100A6 and esophageal squamous cell carcinoma: Among the nine studies, three focused on breast cancer(BC), one on gastric cancer(GC), one on cervical squamous cell (CSC), one on esophageal squamous cell carcinoma(ESCC) , one on ovarian cancer(OC) ,one on small cell lung cancer (SCLC) ,and one on prostate cancer(Pra).The expression of CCAT2 was detected by qRT-PCR and normalized to GAPDH or β-actin.In all of the studies, the patients were divided into two groups: high and low expression of CCAT2.HR and its 95%CI were extracted directly from original data reported in the papers.