Incidence of precancerous foci of mammary glands and growth rate of transplantable mammary cancers in sialoadenectomized mice.

Sialoadenectomies performed on 8-week-old female SHN and GR mice markedly reduced the numbers of precancerous and cancerous lesions in their mammary glands that had been mildly hypoplastic; the mice were necropsied when they were 30 weeks old. The success rate of the mammary cancer transplantation to isogenic male SHN or C3H mice was lower in the sialoadenectomized animals, and growth of the grafted tumors was delayed after gland removal. Some tumor development resumed in the hosts that received mouse epidermal growth factor after surgery. Therefore, we believe this growth factor may play a role in the multistage process of mouse mammary carcinogenesis.