e19052 Background: There is consistent information suggesting that long-term WSE constitutes a risk factor for lung cancer. More than 50 years of WSE was associated with non-small cell lung cancer (NSCLC). In Colombia the prevalence of WSE in areas having less economic development is approximately 24%. The aim of the study was to evaluate WSE as a predictor of response and survival in ALA pts. Methods: This study included 168 pts with ALA treated between 2002 and 2007 in four referring hospitals of Bogotá. Retrospectively, we estimated overall response rates (ORR), time to progression (TTP) and overall survival (OS) in a subgroup of pts with significant WSE (exposure >5 years for at least 4 hours/day) treated with erlotinib, and compared them with the non-WSE population treated with the same compound. Results: Median age was 66 years (range, 29–96), 53% were female, 39% had never been smokers, 24% of all cohort pts had been considerably exposed to WS and 45 pts had received erlotinib during disease treatment (as 2nd or 3rd line). Sixteen of these pts (F11/M5, PS ≥70% 9 pts) had been exposed to WS and 29 not so (F17/M12, PS ≥70% 22 pts); 10 pts having WSE had been smoking for a mean of 14pk/yr history. ORR to erlotinib was 7% and 32% in pts with and without WSE respectively (p = 0.02). TTP was significantly higher in pts treated with erlotinib with no history of WSE (4.9 mo. vs 1.7 mo., p = 0.034). and in those who had received this compound as second-line (vs erlotinib used as third line, p = 0.044). Among pts with WSE history, OS was 6.6 mo. (range, 5.8–7.3) for those treated with Erlotinib and 12.7 mo. (range, 10.2–17) for those not treated with this compound (p = 0.04). Multivariate analysis was carried out for determining the factors influencing mortality between pts with WSE; only PS (HR: 4.6, 95%CI: 1.2–29, p = 0.050) and gender (HR: 3.6, 95%CI: 2.7–18, p = 0.036) were significant. Conclusions: WSE was associated with a poorer response and survival in ALA pts treated with erlotinib in Colombia. No significant financial relationships to disclose.