Survival of patients with lung cancer is unfavorable. Distant metastasis is detected in more than half of the patients at diagnosis. In advanced stages, platinum-based chemotherapy has been the main therapeutic approach for a long time, however, in 2004 targeted therapies emerged. Recently, PDL1/ PD-1 inhibitors have been introduced in the treatment of metastatic lung cancers, for which the therapeutic criteria are increasingly outlined. Based on international and Hungarian data, it is likely that determination of PD-L1 expression in the primary tumor samples may be sufficient for the establishment of therapeutic indication, if PD-L1 expression of tumor cells remains the sole criterion. However, if the combined positive score, which takes into account PD-L1 expression of both tumor and immune cells, will be introduced as a therapeutic criterion, testing of all the actual tumor samples may be required to initiate treatment, as conventional oncotherapies may affect the PD-L1 expression of immune cells.