Influence of smoking dose on the outcome of Japanse patients with non-small cell lung cancer who had gefitinib treatment

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e19004 Background: Non-smoking history and epidermal growth factor receptor (EGFR) mutation are associated with increased sensitivity to gefitinib in non-small cell lung cancer (NSCLC). However, it is still unclear how much smoking dose is associated with survival and response to gefitinib among smokers. Methods: NSCLC patients (pts) with detailed smoking history who received gefitinib at our institution between 9/02 and 9/04 were reviewed. An analysis was conducted to the pts for association between smoking dose, EGFR mutations, performance status (PS), response and overall survival using multivariate analysis. Results: Data were available for 100 pts including 30 females and 70males. We expressed smoking dose as pack year (Py).The median dose of smoking was 32 Py (0.1–100 Py). We defined the group of <10 Py as light smokers(17 pts) and the other group of 10 Py or more as heavy smokers(83 pts). We detected 31(31%) EGFR mutation (median 14 Py 0.1–75 Py) with exon 18 / 19 /21 mutation;3/17/11 pts .Cox survival analysis showed that overall survival was preferably associated with small dose of smoking(<10 Py)(HR=0.505; [95% CI 0.277–0.921; P=0.013]), EGFR mutation(HR=0.452[95% CI 0.235–0.87;P=0.035])and PS;0–1(HR=0.347 [95% CI 0.207–0.583 P<0.001]). EGFR mutations were significantly more frequently observed in light (12/17:71%) than heavy smokers(19/83:23%) (p<0.001). Disease control rate(DCR) was significantly higher in light (13/17;76%;PR 6, SD 7) than heavy smokers(29/83;35%;PR 15, SD 14)(P=0.002), but there was not significant difference between those groups in terms of response rate (RR)(P=0.187). There were significant differences between pts with EGFR mutations (PR 13 SD 14; RR 42%,DCR 87%) and pts without EGFR mutations (PR 8 SD 15; RR 12%, DCR 33%) in terms of RR(P<0.001) and DCR(P<0.001). In pts with EGFR mutation, there was no significant difference between light and heavy smokers in terms of RR (light smokers 5/10, heavy smokers 8/21; P=0.701) and DCR (light smokers 10/10, heavy smokers17/21; P= 0.277). Conclusions: EGFR mutations were predictive factor and prognostic factor. Small dose of smoking (< 10 Py) was prognostic factor, however it was not a predictive factor of smokers with NSCLC. No significant financial relationships to disclose.