FHIT and squamous cell carcinoma: The pooled OR from 8 studies including 490 squamous cell carcinoma (SCC) and 494 adenocarcinoma (AD), is shown in Fig. 5 (OR = 1.49, 95% CI = 1.14–1.95, p = 0.004), which indicates that FHIT hypermethylation plays a more important role in the pathogenesis of SCC.