Main characteristics of studies included in the meta-analysis.

HB: hospital based; PB: population based; Mixed: hospital and population based; NR: not reported; PTC: papillary thyroid carcinoma; ESCC: esophageal squamous cell carcinoma; SCCHN: squamous cell carcinoma of the head and neck; NSCLC: non-small cell lung cancer; CSCC: cervical cancer; TNBC: triple negative breast cancer; OSCC: oral squamous cell carcinoma; CRC: colorectal cancer; PCR-RFLP: polymerase chain reaction–restriction fragment length polymorphism; HRMA: high-resolution melting analysis; PIRA–PCR: primer-introduced restriction analysis-polymerase chain reaction; PCR-LDR: polymerase chain reaction-ligation detection reaction; PCR-FRET: polymerase chain reaction-fluorescence resonance energy transfer; Tm-shift: melting-temperature –shift allele-specific genotyping; HWE: Hardy-Weinberg equilibrium; P: p value.