Cigarette smoking and p53 mutations in lung cancer and bladder cancer

We report here a compilation of p53 mutation results from two smoking-related cancers, lung cancer and bladder cancer. The overall mutation frequencies reported for these two types of cancer were relatively similar-50% in lung cancer and 40% in bladder cancer. The compiled data from lung cancer and bladder cancer suggest an increasing proportion of patients with p53 mutations in nonsmokers, former smokers, and current smokers, in that order, in both cancer groups. Taken together, more than half (55% and 56% for lung cancer and bladder cancer, respectively) of the patients who continued smoking (CS), less than 40% (38% and 38%) of those who had stopped smoking before (greater than or equal to 1 or greater than or equal to 5 years) clinical diagnosis (ES), and less than 30% (25% and 29%) of those who were nonsmokers (NS) had a p53 mutation. The differences seen in the mutation frequencies between the three smoking groups did not, however, reach statistical significance (lung cancer-CS vs ES: odds ratio [OR]=2.0, 95% CI 0.7-5.4; CS vs NS: OR=3.7, 95% CI 0.4-37; bladder cancer-CS vs ES: OR=2.1, 95% CI 0.6-7.9; CS vs NS: OR=3.1, 95% CI 0.7-13). Guanine to thymine transversions were the most common type in lung cancer followed by guanine to adenine transitions. In bladder cancer, on the contrary, G:C to A:T transitions at cytosine-guanine dinucleotide sites were the most frequently detected base substitutions. Analysis of the compiled p53 mutation data suggests that, in addition to lifetime cumulative exposure to cigarette smoke, also slopping smoking for years prior to clinical manifestation of the disease may affect the incidence of p53 mutations. The differences in the mutation profiles appear to support the view that the main genotoxic agents from cigarette smoke exposure may be different in bladder cancer as compared to lung cancer, as suggested previously by DNA adduct studies.