Two-stage and Weibull models for carcinogenesis applied to the ED01 discontinued dosing data.

The two-stage clonal expansion model for a single, less-than-lifetime period of dosing is formulated and applied to the liver and bladder tumor data from the ED01 study. The model successfully predicts liver tumor incidence for time points beyond termination of dosing with 2-acetylaminofluorene, but it is unsuccessful for bladder tumor incidence. A discontinued dosing version of the Weibull model is proposed and is shown to predict successfully both liver and bladder tumor incidences for time points after termination of dosing.