ERCC1 and nasopharyngeal carcinoma: A meta-analysis [22–24] showed that high ERCC1 expression is related to adverse prognosis of OS in NPC (HR = 2.72, 95% CI 1.79–4.13, P < 0.001), but not significantly related to the clinical characteristics DFS, DMFS, and LRFS; however, sample sizes of individual studies were small, and conclusions were not consistent.