A STEM-CELL MODEL FOR CARCINOGENESIS

A modification to the well-known two-stage model of carcinogenesis wit h clonal expansion is proposed. A true stem cell is applied to the pro duction of intermediate cells by incorporating a birth-death process w ith a reflecting barrier into the model. The distribution of the numbe r of detectable intermediate cell clones is derived, and systems of di fferential equations are formulated for the cumulative distribution fu nction for the appearance of malignant tumors. The model is applied to data on papilloma formation in a mouse skin painting experiment. Test s for the importance of intermediate cells in tumor incidence can be d erived.