Age incidence curves for cancer.

Age incidence curves for carcinomas tend to be linear on doubly logarithmic graphs. This fact has been used to support the somatic mutation hypothesis. It is shown that this should also be expected on the epigenetic hypothesis when the reversible cellular changes are programmed to occur randomly. Such changes could be programmed differently to obtain the age incidence curves observed for other cancers, e.g., leukemias and sarcomas.