By screening all consecutive patients diagnosed with stage I-II NSCLC and molecularly assessed between 2016–2018 in Västra Götaland, the second largest county in Sweden with a population of 1.7 million, the current retrospective cohort study provides a unique real-world dataset for assessing the impact of combining KRAS mutations with primary tumor size. Here, KRAS is linked to non-small cell lung carcinoma.