Gastric acid-suppressing medications (AS), namely, proton pump inhibitors and histamine-2 receptor antagonists, increase gastric pH, which may reduce the absorption of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors—erlotinib and gefitinib.

From 2008 to 2011, 130 consecutive patients with advanced non–small-cell lung cancer (NSCLC) harboring EGFR mutations were treated with either erlotinib or gefitinib at our institution. The clinical characteristics of the patients were reviewed, and the efficacy and toxicity of erlotinib and gefitinib were compared for patients receiving and not receiving AS.

Among the 130 patients, 47 received AS (AS users group), while the remaining 83 patients did not (AS non-users group). The overall response rate (ORR) and median progression-free survival (PFS) in the subject population was 60% and 10 months, respectively. In the AS users and non-users groups, the ORR was 64% and 63% (P = .92), while the median PFS was 8.7 and 10.7 months (P = .13), respectively. No significant difference in either ORR or PFS was observed between the 2 groups. With regard to the toxicity, the frequencies of rash (83% vs. 86%; P = .60) and diarrhea (34% vs. 29%; P = .55) were similar for both groups. A multivariate analysis identified that AS use was not a significant factor for either PFS or OS.

Concurrent use of AS did not affect the efficacy or toxicity of erlotinib and gefitinib in patients with advanced NSCLC harboring EGFR mutations.