Characteristics of studies included in the meta-analysis.

MPM, malignant pleural mesothelioma; UDTC, upper digestive tract cancer; HB, hospital–based control; PB, population-based control; APEX, arrayed primer extension; PCR, polymerase chain reaction; RFLP, restriction fragment length polymorphism; SSCP, single strand conformation polymorphism; AS, allele-specific; ASO, allele-specific oligonucleotide; MALDI-TOF-MS, matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry; NA: not available.
*Power was calculated by the PS software with MAF in controls as the frequency of risk factor and OR was selected with 1.2, 1.5 and 2 as the relative risk.