Detection of K-ras mutations of bronchoalveolar lavage fluid cells aids the diagnosis of lung cancer in small pulmonary lesions

An increased prevalence of K-ras oncogene mutation in lung adenocarcinoma h as been shown by PCR-primer-introduced restriction with enrichment for muta tion alleles (PCR-PIREMA) experiments. In the present study we investigated whether this method is useful for the diagnosis of lung cancer in small pu lmonary lesions, which are difficult to diagnose cytologically as lung canc er by bronchoscopic examination, We examined bronchoalveolar lavage fluid ( BALF) cells from 33 patients with single nodular pulmonary lesions of less than 2 cm in diameter (measured on chest computed tomography scans) for K-r as (codon 12) mutation, by PCR-PIREMA, Transbronchial fiberscopic examinati ons had not revealed lung cancer cytologically in any of the patients, The final diagnoses for the 33 lesions were 20 adenocarcinomas, 5 cases of foca l fibrosis, 5 cases of pneumonia, I case of tuberculosis, 1 hamartoma, and 1 case of lymph node swelling, BALF cell lysates were amplified and digeste d with a restriction enzyme to detect the K-ias oncogene. Only the normal K -ras was observed after the first amplification and digestion for each of t he 33 patients. Three amplifications and digestions were performed for each sample, We detected mutation of K-ras in BALF cells from 15 (75%) of 20 lu ng cancer patients and in cells from only 4 (31%) of 13 patients with nonma lignant lesions. The detection rate of the K-ras mutation in lung cancer wa s significantly greater than that in nonmalignant lesions (P = 0.012). Our results indicate that the detection of the codon 12 K-ras mutation in BALF cells by PCR-PIREMA aids the diagnosis of lung cancer in patients with smal l pulmonary lesions with negative cytological findings.