Sex hormone involvement in the development of experimental virally induced murine salivary gland tumors.

Mice were given a single inoculation of polyoma virus at birth and then orchidectomised or oophorectomised. Unoperated groups received polyoma virus alone whilst further males received testosterone, and females received oestradiol thrice-weekly in addition to polyoma virus inoculation. All groups were then observed over the succeeding 370 days for the development of tumors of the submandibular and parotid salivary glands. Polyoma virus inoculation selectively induced salivary gland tumors in 70% of male animals and 30% of female animals given polyoma virus alone. Testosterone therapy increased the salivary tumor frequency from 69-90% whilst orchidectomy reduced the tumor frequency to 50%. Oophorectomy or oestrogen therapy did not significantly alter the salivary gland tumor frequency in females but oestrogen therapy did result in the development of second primary tumors of breast in 60% of female animals bearing salivary gland tumors. The role of androgens in the development of virally induced salivary gland tumors is discussed as are the possible mechanisms responsible for the development of second primary tumor of breast.