PIWIL1 and cancer: In summary, the overall results specifically suggested that high PIWIL1 expression was associated with poor prognosis in cancers, with results of poor OS (pooled HR = 1.80, 95% CIs: 1.52–2.14, p < 0.00001), poor CSS (pooled HR = 1.94, 95% CIs: 1.47–2.55, p < 0.00001), and poor DFS/RFS (pooled HR = 2.22, 95% CIs: 1.52–3.24, p < 0.00001).