PDCD1 and lung cancer: Methods: In an attempt to better understand the nature of these differences, we searched the available literature for reports connecting sex specific bioactive molecules—including estrogens, progesterone, testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, leptin, and activin/inhibin—to sex differences in lung cancer and the response to PD-1/PDL-1 therapies.