Limitations on obtaining biomarker's expression levels in patients with non-small cell lung cancer (NSCLC): Are there any differences between surgical biopsies, bronchoscopy, or core biopsies?

e21039 Background: EGFR mutation is predictive for chemotherapy and TKI response in patients (pts) with NSCLC. ERCC1, RRM1 and TS might also have predictive value. The main difficulty in evaluating these tumor biomarkers (BM) is related to the amount of tissue available. It is unclear whether any specific biopsy technique improves the detection of these BM. We looked into the differences in obtaining successful BM expression in pts with NSCLC depending on biopsy technique used as diagnostic tool. Methods: We did a cross-sectional study of pts with NSCLC with tissue available for evaluation of BM expression. The main endpoint was to evaluate expression levels of ERCC1, RRM1, TS, and the presence of EGFR and K-ras mutation, and compare current biopsy techniques to achieve this goal. BM data was obtained from tumor samples by using ResponseDx test: RNA expression of ERCC1, TS, and RRM1 was analyzed by RT-PCR and PCR analysis of DNA was used to determine K-ras and EGFR mutation status. Statistical analysis wa...