[A simple look at the molecular biology of lung cancer: K-Ras]

Ras genes encode a family of membrane proteins involved in the regulation of cell growth. Mutations of Ras stimulate cell growth and thus can play a role in carcinogenesis. The search for mutations of Ras is possible by PCR on bronchial biopsies or surgical specimens. They are found in 15 to 20% of non-small cell lung cancers. In the disease's early stage, the presence of a Ras mutation can be a negative predictor of the effectiveness of adjuvant chemotherapy. In the advanced stage of the disease, it is a factor predicting a poor prognosis. Although prospective studies have found no statistically significant negative influence of the presence of a mutation of Ras on the effectiveness of tyrosine kinase inhibitors of EGFR, it is likely that these treatments will be of limited value in this population given the lack of response observed when Ras is mutated. Prospective and functional studies are needed to determine the value of the different mutations observed.