By including all consecutive patients diagnosed with Stage IV NSCLC and molecularly assessed between 2016–2018 in West Sweden, the current retrospective cohort study provided a unique real-world dataset for assessing the impact of KRAS mutations and PD-L1 expression on OS following first-line standard of care, including platinum doublet chemotherapy and immunotherapy. This evidence concerns the gene KRAS and non-small cell lung carcinoma.