PARP1 and lung adenocarcinoma: When patients homozygous for two or three gene variants were combined as one group, we found an increased OR of 1.89 (95% CI: 1.24–2.88; P = 0.003) for lung adenocarcinoma individuals with more than one homozygous variant allele of hOGG1 326 Cys/Cys, APE1 148Glu/Glu and ADPRT 762Ala/Ala.