GRPR and lung cancer: A stratified analysis by smoking status indicated that presence of GRPR expression in bronchial cells was significantly associated with lung cancer for never smokers (O.R. = 17.0; 95% C.I = 3.32-87.13) and former smokers (O.R. = 3.69; 95% C.I = 1.88-7.29) but not active smokers (O.R. = 1.18; 95% CI = 0.34-4.15) (Figure 1), and these odds ratios differed significantly (P < 0.001, Mantel-Haenszel test of homogeneity (M-H test)).