Aging increases susceptibility of mouse skin to DMBA carcinogenesis independent of general immune status.

The dependence of chemical carcinogenesis on age of target tissue was studied by repeated DMBA-treatment of mouse skin grafted from old and young syngeneic donors to young recipients. Carcinomas developed on 39 percent (1.6/41) of grafts from old donors and on 12 percent (5/41) of grafts from young donors. The incidence of nonskin lymphoid tumors was highest in male recipients bearing grafts from old donors.