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.