PURPOSE: EGFR mutations condition the clinical response of NSCLC to novel chemotherapeutic agents such as Erlotinib. We sought to determine the feasibility of identifying such mutations in DNA extracted from stained slides in patients with lung cancer diagnosed by TBNA of mediastinal adenopathy or endobronchially visible disease.
METHODS: We performed conventional DNA extraction from papanicolau stained slides of TBNA material obtained from 27 patients with NSCLC (25 lymph nodes and 2 endobronchial tumors). 15 patients had adenocarcinoma, 6 had poorly differentiated NSCLC, 2 had squamous histology, 1 a large cell carcinoma, and 3 were unspecified. The cytopathologist reviewed all slides selecting only those with abundant tumor cells, few lymphocytes and/or bronchial epithelial cells. PCR amplification and direct sequencing of exons 18, 19, and 21 of the EGFR gene were performed. Each sample was sequenced in duplicate according to the manufacturer′s specifications in both forward and reverse directions using an ABI prism 310 (Applied Biosystems). The sequences were then compared with the GenBank-archived human sequence of EGFR.
RESULTS: EGFR mutations were identified in 7 patients (26%), 3 adenocarcinomas, 1 squamous cell carcinoma, 1 poorly differentiated carcinoma, and 2 unspecified carcinomas.
CONCLUSION: TBNA samples can yield adequate material for EGFR mutation analysis, even after staining, thus providing valuable information which might guide therapeutic decisions in patients with NSCLC.
CLINICAL IMPLICATIONS: EGFR mutations which predict clinical response to chemotherapy with Erlotinib may be detected in processed slides from patients with lung cancer, precluding the need for multiple biopsies.
DISCLOSURE: Luis Seijo, No Financial Disclosure Information; No Product/Research Disclosure Information