Main characteristics and results of the eligible studies.

Abbreviations: IHC, immunohistochemistry; qPCR, quantitative real-time polymerase chain reaction; FISH, fluorescence in situ hybridization; IF, immunofluorescence; SCC, squamous cell carcinomas; ADC, adenocarcinomas; M, mean; SD, standard deviation.
Note:
*only with SCC patients;