Background: We hypothesize that among patients with lung cancers the KRAS/EGFR mutation profile and overall survival of collegiate smokers (former smokers who smoked between 101 lifetime cigarettes and 5 pack-years) are distinct from those of never smokers and former smokers with 15 pack-years or more.
Methods: We collected age, sex, stage, survival, and smoking history for patients evaluated from 2004 to 2009 with advanced stage lung cancers and known KRAS/EGFR status. Mutation profile and overall survival were compared using Fisher's exact test and log-rank test, respectively.
Results: Data were available for 852 patients with advanced-stage lung cancers with known KRAS/EGFR status, of which 6% were collegiate smokers, 36% were never smokers, and 30% were former smokers with 15 pack-years or more. The mutation profile of collegiate smokers (15% KRAS mutations, 27% EGFR mutations) was distinct from those of never smokers (p < 0.001) and former smokers with 15 pack-years or more (p < 0.001) and not significantly different from those of former smokers with 5 to 15 pack-years (p = 0.9). Median overall survival for collegiate smokers was 25 months, compared with 32 months for never smokers (p = 0.4), 33 months for former smokers with 5 to 15 pack-years (p = 0.48), and 21 months for former smokers with 15 pack-years or more (p = 0.63).
Conclusions: Collegiate smokers with advanced-stage lung cancers represent a distinct subgroup of patients with a higher frequency of KRAS mutations and lower frequency of EGFR mutations compared with never smokers. These observations reinforce the recommendation for routine mutation testing for all patients with lung cancers and that no degree of tobacco exposure is safe.