A biological involvement of sex hormones in pathogenesis of lung cancer, particularly adenocarcinoma, seems plausible based on the presence of specific estrogen and progesterone receptors in normal and some malignant lung tissues,7-10 animal experiments,11-12 and effects of sex hormones on other non-target tumors.13-15 However, the exact mechanism and whether it is similar to other hormone-dependent tumors is unknown. Here, PGR is linked to lung cancer.