KRAS mutation is one of the common oncogenes mutations that are related to poor prognosis of lung cancer and is strongly associated with smoking.12–19 This study follows on from a study by Soerosoet al. which analyzed KRAS mutations in the population of North Sumatra.20 However, there were no KRAS exon 2 mutations among the subjects of this study. Here, KRAS is linked to lung cancer.