Abstract
Excess relative risk of lung cancer among atomic-bomb survivors remains high even more than 60 years after the bombings. To assess effects of radiation on lung carcinogenesis, we first investigated mutations in the p53 (exons 5-8) and EGFR (exons 18, 19 and 21) genes examined association between the mutation status and radiation exposure among 20 atomic-radiation-exposed and 18 non-exposed patients with non-small cell lung cancer. Mutations of the p53 gene were found in 11 of the 20 exposed patients (55%) and in 6 of the 18 non-exposed patients (33%). Next, we separately analyzed p53 mutations in squamous cell carcinoma (Sq) and adenocarcinoma (Ad). Mutations of the p53 gene were found in 5 of 6 exposed Sq patients (83%) and in 2 of 5 non-exposed Sq patients (40%); in 5 of 12 exposed Ad patients (42%) and in 3 of 12 non-exposed Ad patients (25%). Furthermore, median radiation dose among lung cancer patients with p53 gene mutation of GC>TA transversion was higher than that of patients with other types of mutations or without mutation. On the other hand, among 12 radiation-exposed patients of lung adenocarcinoma, 2 had an EGFR mutation, a lower-than-expected frequency. These results suggest the possibility that frequencies of certain gene mutations (e.g. p53) and the types may be associated with radiation exposure in a histological dependent manner, although further analyses with increased number of cases are required.
