Detection of Point Mutations of K-ras Oncogene and p53 Tumor-Suppressor Gene in Sputum Samples

: Mutations in the p53 tumor-suppressor gene and K-ras oncogene have been frequently found in sputum and bronchoalveolar lavage samples of lung cancer patients and also in those of patients prior to presenting clinical symptoms of lung cancer, suggesting that they may provide useful biomarkers for early lung cancer diagnosis. However, the detection of these mutations has been complicated by the fact that they often occur in only a small fraction of epithelial cells among sputum cells, and, in the case of the p53 gene, inactivating mutations may occur at many codons. This chapter describes methods to identify p53 and K-ras mutations present in low fractions of epithelial cells among the excess of other cell types in sputum samples from lung cancer patients.