Survival curves and incidence of neoplastic and non-neoplastic disease in SENCAR mice.

The survival curves and the incidence of spontaneous diseases were studied in a population of SENCAR mice, a stock derived by a selected breeding protocol for enhanced susceptibility to chemical carcinogenesis in the skin. SENCAR mice proved to be as long-lived as other mouse strains or stocks, including one of their parental lines, Charles River CD-1. The most frequently occurring neoplasias in SENCAR mice were lymphoma, myeloid leukemia and reticulum cell sarcoma. Other frequently occurring neoplastic diseases included lung adenomas and carcinoma and mammary gland carcinoma. However, the incidence of these tumors was not higher than the incidence in CD-1 mice or other mouse strains or stocks. A variety of non-neoplastic diseases, both inflammatory and degenerative, were also observed in old mice. The most common were liver, spleen and kidney amyloidosis, pyelonephritis and papillary necrosis. These data indicate that selective breeding for susceptibility to chemical carcinogenesis has not produced a concomitant increase in the incidence of spontaneous neoplastic and non-neoplastic disease.