“…HRs and 95% CIs were available in 19 studies[38,39,40,24,41,13,25,42,20,43,21,44,45,46,47,37,48,49,50]. In the remaining studies, the values were extracted from the published survival curves in 14 studies[51,35,52,12,53,54,55,56,17,11,16,57,23,58], and estimated from the variance and its P -value (the Log-rank test) from one study[36] using the statistical methods previously reported[26]. The pooled HR and 95% CI values of these 34 studies were estimated (HR 1.786, 95% CI 1.550–2.060), but significant heterogeneity was observed among these studies with respect to OS ( I
2 = 77.7%, n = 34, P < 0.001: Table 2).…”