K-ras gene mutation in sputum samples containing atypical cells and adenocarcinoma cells in the lung.

We analyzed the presence or absence of K-ras mutations in sputum samples with atypical cells by colony hybridization. The frequency of K-ras mutations in 104 patients with adenocarcinoma of the lung was also examined using dot blotting. No mutations in K-ras codon 12 were detected in the 12 sputum samples examined, which included three specimens from patients who later developed lung adenocarcinoma. Because of the paucity of sputum samples, it was difficult to conclude whether K-ras gene mutations are useful for molecular screening for lung cancer at the present time. Secondly, we detected 12 cases [12%; 10 males (19%) and two females (4%)] with a K-ras mutation among 104 patients with lung adenocarcinoma. Although the smoking rate of patients (89%) was higher than the general Japanese male population (approximately 60%), indicating that smoking may be related to the occurrence of adenocarcinoma of the lung, it was unclear whether smoking was related to K-ras mutation from our results. Other factors may contribute to K-ras mutation.