Little has been studied regarding anti-progesterone therapy in NSCLC, however, a recent preclinical study showed that PR contains a polyproline domain (PPD) that inhibits NSCLC cell proliferation and has a synergistic effect when given in combination with EGFR TKIs while another preclinical study demonstrated that progesterone can inhibit lung adenocarcinoma cell growth via membrane progesterone receptor alpha (49, 50). This evidence concerns the gene PGR and lung adenocarcinoma.