Body mass index and exon 19 mutation as factors predicting the therapeutic efficacy of gefitinib in patients with epidermal growth factor receptor mutation‐positive non‐small cell lung cancer

BACKGROUND: Many randomized clinical trials have demonstrated that epidermal growth factor receptor‐tyrosine kinase inhibitors (EGFR‐TKIs) are advantageous over standard chemotherapy, either as front‐line treatment or as further management of patients with EGFR mutation‐positive non‐small‐cell lung cancer (NSCLC). However, which subgroup of these patients could benefit more from EGFR‐TKIs needs to be further explored. In the present study, we explored the predictive factors in such cohorts of patients who received gefitinib. METHODS: The study included 95 patients with EGFR mutation‐positive advanced NSCLC who received gefitinib treatment. Multivariate analysis of progression‐free survival (PFS) was performed using classification and regression tree (CART) analysis to assess the effect of specific variables on PFS in subgroups of patients with similar clinical features. RESULTS: The median PFS in patients with EGFR mutation‐positive advanced NSCLC who received gefitinib treatment was 13.3 months (95% confidence interval 9.4–17.2). CART analysis showed an initial split on body mass index (BMI); subsequently, three terminal subgroups were formed. The median PFS in the three subsets ranged from 8.2 to 15.2 months, in which the subgroup with a BMI less than or equal to 20.8 kg/m(2) had the longest PFS (15.2 months). In addition, PFS in the EGFR exon 19 mutation group was better than in the other mutation site group (10.3 vs. 8.2 months). CONCLUSIONS: BMI and exon 19 mutation may be predictors of PFS in patients with EGFR mutation‐positive advanced NSCLC who receive gefitinib treatment. Both active EGFR mutation and patient‐specific factors may be used to predict the therapeutic efficacy of EGFR‐TKIs.