The incidence rate of DEN-induced tumor formation for Ku703A/3A mice is 12.5 times (95% CI 3.51–44.14) higher at 4 months, 5.6 times (95% CI 2.65–12.01) higher at 6 months, and 1.7 (95% CI 0.77–3.86) times higher at 9 months compared to Ku70+/+ mice (Figure 4D). Control (DEN-untreated) Ku703A/3A and Ku70+/+ mice did not develop any tumors when the experiment was terminated 9 months post-treatment. This evidence concerns the gene XRCC6 and neoplasm.