2.3. Data extraction

The data was extracted and the bias risk was assessed according to the PRISMA recommendation separately by 2 reviewers (H-ZX and Z-W) after the articles were filtrated. The information we obtained from each study are as follows: surname of the first author, publication place, publication date, total sample size, cancer type, sample source, tumor stage, lymph node metastasis, clinicopathological features, follow-up time, outcome measures, analysis type, and the detection method of SNHG12 expression. OS was used to evaluate the patients prognosis and were determined by Kaplan–Meier analysis. By using Engauge Digitizer 4.1 to analyzed the Kaplan–Meier survival curves, we converted the image into data. Hazard Ratio (HR) and 95% confidence intervals (95%CI) of each study were calculated by the HR calculations spreadsheet mentioned in Jayne F Tierneys article.^[30]