OBJECTIVETo validate the feasibility for detecting EGFR and k-ras mutations using cytological specimens.

METHODSCytological specimens including fine-needle aspiration (FNA), pleural effusion (PLE) and fiberoptic bronchoscopic (FOB) brushing were collected from patients with non-small cell lung cancer (NSCLC ) from January 2011 to July 2011 at the Department of Cytology, Cancer Hospital, Chinese Academy of Medical Sciences (CHCAMS). Polymerase chain reaction (PCR) was carried out to amplify EGFR exons 18-21 and k-ras codons 12-13, and then the PCR products sequencing and analysis were performed.

RESULTSFifty cytological specimens were collected including 19 cases of FOB, 9 cases of FNA, 22 cases of PLE. Of them DNA was successfully extracted in 43 cases, and specific PCR amplification products sequencing were performed in 42 cases. EGFR mutations were detected in 14 of 42 specimens (33.3%), the frequencies of EGFR mutations in exons 19, 20 and 21 were 16.7% (7/42), 4.8% (2/42) and 11.9% (5/42), respectively, and no mutation was found in exon 18. Higher frequencies of EGFR mutations were detected in exons 19 and 21 (85.7%). Mutations were identified in 38.7% (12/31) cases of adenocarcinoma. K-ras mutations were found in 2 of 42 specimens (4.8%). EGFR and K-ras mutations were not found in the same case.

CONCLUSIONSCytological specimens are feasible for detecting EGFR and K-ras mutation. This is especially beneficial in patients in whom histological materials can not be obtained.