Breast cancer-resistance protein expression using immunohistochemical staining and treatment by gefitinib for non-small cell lung cancer

Objective. Somatic EGFR mutations correlate with hypersensitivity to gefitinib. However, there is a subset of cancer patients with EGFR mutations that do not respond well to gefitinib treatment. We examined breast cancer resistance protein (BCRP) expression and sensitivity to gefitinib. Materials and Methods. We studied 48 surgically resected non-small cell lung cancer (NSCLC) with postoperative recurrence. These patients were examined for BCRP expression immunohistochemically and mutations of EGFR exon18-21. Postoperative recurrence in cases treated with gefitinib and responses were assessed. Results. BCRP expression was detected in 7 of 48 (14.6%). EGFR mutations were detected in 17 of 48 (35.4%). In cases with EGFR mutation, there was only one case of no response, which was also found to have positive immunohistochemical staining for BCRP. Conclusion. Resistance to gefitinib by NSCLC with EGFR mutation may be recognized by BCRP expression.