A stochastic two-stage carcinogenesis model: a new approach to computing the probability of observing tumor in animal bioassays.

A new definition of probability of observing tumor in animal bioassay is developed. It is derived from a two-stage stochastic model for carcinogenesis with time-dependent birth and death rates for cell proliferation. The model takes into account the method of collecting data on preneoplastic and neoplastic lesions. The new definition is appropriate for analyzing the presence or absence of tumors in animal bioassays.