Introduction: The expression of PD-L1 as a predictive marker of response to treatment of non-small cell lung cancer (NSCLC) allows the identification of patients most likely to benefit from treatment with inhibitors of immune checkpoints. The main objective of this study was to determine the PD-L1 positivity/negativity rates of biopsies diagnosed with NSCLC during the year 2017 and 2018 at CHUPorto and compare ...