Molecular detection of tumor cells in bronchoalveolar lavage fluid from patients with early stage lung cancer

Background: Conventional cytologic analysis of sputum is an insensitive tes t for the diagnosis of non-small-cell lung cancer (NSCLC), We have recently demonstrated that polymerase chain reaction (PCR)-based molecular methods are more sensitive than cytologic analysis in diagnosing bladder cancer. In this study, we examined whether molecular assays could identify cancer cel ls in bronchoalveolar lavage (BAL) fluid. Methods: Tumor-specific oncogene mutations, CpG-island methylation status, and microsatellite alterations in the DNA of cells in BAL fluid from 50 consecutive patients with resectable (stages I through IIIa) NSCLC were assessed by use of four PCR-based techn iques. Results: Of 50 tumors, 28 contained a p53 mutation, and the identica l mutation was detected with a plaque hybridization assay in the BAL fluid of 39% (11 of 28) of the corresponding patients. Eight of 19 adenocarcinoma s contained a K-ras mutation, and the identical mutation was detected with a mutation ligation assay in the BAL fluid of 50% (four of eight) of the co rresponding patients. The p16 gene was methylated in 19 of 50 tumors, and m ethylated p16 alleles were detected in the BAL fluid of 63% (12 of 19) of t he corresponding patients. Microsatellite instability in at least one marke r was detected with a panel of 15 markers frequently altered in NSCLC in 23 of 50 tumors; the identical alteration was detected in the BAL fluid of 14 % (three of 22) of the corresponding patients. When all four techniques wer e used, mutations or microsatellite instability was detected in the paired BAL fluid of 23 (53%) of the 43 patients with tumors carrying a genetic alt eration. Conclusion: Although still limited by sensitivity, molecular diagn ostic strategies can detect the presence of neoplastic cells in the proxima l airway of patients with surgically resectable NSCLC.