Benign and Malignant Tumor Induction in Mouse Skin

Carcinogenesis has often been assumed to be a multistage disease where a single cell progresses from normal to cancer in discrete sequential stages1,2,3. There is statistical support for the existence of such stages in the shape of functions that describe the dependence of cancer yield on dose and time. Biological evidence in favor of the multistage theory is derived from chromosomally marked clones seen in exacerbations of myeloid leukemia and in the progressive acquisition of automony seen in certain types of tumors, especially, hormone dependent tumors4,5.