Association of body mass index (BMI) and stage in patients with non-small cell lung cancer harboring KRAS mutations.

Abstract

e13071 Background: Body mass index (BMI) is inversely associated with lung cancer risk, particularly in former or current smokers. KRAS mutant non-small cell lung cancer (NSCLC) has been shown to be highly associated with smoking status. Therefore, we sought to investigate the association of BMI and stage in a cohort of patients with KRAS mutant NSCLC. Methods: Patients with KRAS mutant lung cancer who underwent tumor genotyping using next generation sequencing testing were identified. BMI( kg/m2 ) was categorized as: Underweight ( < 18.5), normal weight (18.5 – 24.9), overweight (25-29.9) and obese (≥30). Chi-square and t-tests were performed to test association between stage (I vs. II+) and BMI (4 categories), and stage and BMI as a continuous variable, respectively. Results: From 5/2013 to 9/2016, 201 patients with KRAS mutant NSLC were identified. Of these, 178 (88.6%) were current or former/ever smokers (SM) and 23 (11.4%) were never smokers (NS). In the SM group, 114 were female and 64 male with a median age at diagnosis of 66.5 years (range 45-93). In the NS group, 15 were female and 8 male with a median age at diagnosis of 71.5 years (range 51-92) (age for NS vs. SM p = 0.0439). Fifty-two (25.9%) patients presented with stage I disease, 149 (74.1%) presented with advanced (stage II-IV) disease. There was no significance in the BMI at diagnosis of SM vs. NS or by sex. There was a difference (p = 0.0430) in the BMI between patients with stage I disease (mean 28.6) and patients with stage II or greater disease (mean 26.6). This was also seen in SM with stage I vs. II+ disease (p = 0.0417); however, this was no longer significant in SM when broken out by sex or in NS alone. Conclusions: We identified a significant difference in BMI in patients with KRAS mutant NSCLC with stage I vs. advance stage disease, with a higher BMI associated with early stage disease at diagnosis. The lower BMI in patients with more advanced stage may be a confounding variable explained by comorbidities, and the lung cancer itself. It is unlikely that treatment effects were a factor as the KRAS testing was done prior to initiating therapy. Further studies looking at BMI and survival analysis in patients with mutant KRAS NSCLC are warranted.