Outcomes of Malaysian patients with advanced lung adenocarcinoma and unknown epidermal growth factor receptor mutation status treated with gefitinib

Aims: To evaluate the response and progression‐free survival (PFS) of Malaysian patients with advanced lung adenocarcinoma and unknown epidermal growth factor receptor (EGFR) mutation status treated with gefitinib. Methods: A retrospective analysis of consecutive patients with EGFR mutation unknown stage III or IV lung adenocarcinoma with EGFR mutation unknown treated with gefitinib until disease progression. Results: Of 71 patients, none had complete response while 26 (36.6%) had partial response and 26 (36.6%) had stable disease. Multivariate analysis showed the independent predictor of response to gefitinib was Eastern Cooperative Oncology Group (ECOG) performance status 1 (odds ratio [OR] 5.39, 95% confidence interval [CI 1.64–17.74]P = 0.006). The median PFS was 6.5 months and was significantly longer in female than male patients (39.0 vs 21.2 weeks; P < 0.001), never smokers vs smokers (32.3 vs 8.3 weeks, P = 0.001), and stage III versus stage IV disease (44 vs 24 weeks, P = 0.021). In a multivariate Cox proportional hazards model with age group, gender, ethnicity, smoking history, disease stage, ECOG performance status and prior cytotoxic chemotherapy as covariates, the independent predictors of longer median PFS were female gender (HR 95% CI 0.38 [0.22–0.66]; P < 0.001) and stage III disease (HR 95% CI 0.54 [0.30–0.98], P = 0.042). Conclusion: In our patients with EGFR mutation unknown advanced lung adenocarcinoma treated with gefitinib, the response rate was 36.6% and the median PFS was significantly longer in female patients, never smokers and patients with stage III disease.