Lung cancer is the leading cause of cancer mortality among Canadians.  It is estimated that 1-4 % of patients with non-small cell lung cancer (NSCLC) will subsequently develop a second primary NSCLC each year. Mutation analysis in EGFR, KRAS and ALK genes in NSCLC have helped guide targeted therapy. Although, the presence of a KRAS mutation has been shown to be a negative prognostic indicator in colorectal cancer, the results in NSCLC are mixed. Furthermore, small studies have suggested KRAS mutations may increase the risk of developing a second primary NSCLC. 
This study is a retrospective cohort study looking at NSCLC specimens from February 28, 2005 to December 31, 2015 obtained from curative resections for stage I and stage II disease. The primary objective is to determine the incidence of second primary lesions in KRAS wild type compared to mutant individuals. Secondary objectives are to determine prognostic implication of possessing a KRAS mutation on overall survival and disease free survival. KRAS wild type and mutant lesion characterstics are compared using a Mann-Whitney test.  Overall and Disease-free survival for each stage and overall are shown using the Kaplan-Meier method with the log-rank test implemented to evaluate differences in outcome. All statistical analyses were performed using MedCalc Statistical Software version 17.2.
KRAS mutant individuals are more likely to have synchoronous lesions found after resection (OR 2.61, p<0.05). Moreover, 74% of these occur within the same lobe. KRAS mutant individuals have more lesions that wild type individuals (1.3 vs. 1.12, p<0.05). There was no statistical difference in the incidence rate of metachronous lesions, overall survival and disease free survival between KRAS mutant and wild type individuals. Though KRAS status does not appear to impact prognosis; it should considered when deciding between lobectomy or sublobar resection given the propensity for synchornous lesions.

Impact of KRAS mutations in early stage non-small cell lung cancer