4-Nitroquinoline-1-Oxide-Induced Mutagen Sensitivity and Risk of Nonmelanoma Skin Cancer: A Case–Control Analysis

The UV radiation-mimetic chemical 4-nitroquinoline-1-oxide (4-NQO) is thought to induce squamous cell carcinoma (SCC) similar to those induced by UV radiation in animals. Therefore, we tested the hypothesis that cellular sensitivity to 4-NQO is associated with risk of developing skin cancer in a case–control study of 191 patients with nonmelanoma skin cancer (NMSC; 81 SCC and 110 basal cell carcinoma (BCC)) and 176 cancer-free controls. Short-term blood cultures were treated with 4-NQO at a final concentration of 10μm for 24hours and scored for chromatid breaks in 50 well-spread metaphases. We found that the mean frequency of chromatid breaks per cell (b/c) was significantly higher in the cases (mean±SD, 0.46±0.43 for SCC and 0.43±0.38 for BCC) than in the controls (0.25±0.25; P