The effect of treatment with Corynebacterium parvum on the development and growth of experimental hematogenic metastases of schwannoma in the rat.

Single i.v. administration of Corynebacterium parvum 5 days before i.v. injection of 10(6) tissue cultured syngeneic schwannoma cells in Lewis rats resulted in extension of survival time (P less than 0.05). There was a significant decrease in metastatic tumor incidence for lung, heart, and kidney and decreased lung tumor growth with approximately 50% of the lung tumor burden of untreated controls (P less than 0.05). Rats treated similarly with C. parvum 10 days after tumor cell injection showed no enhanced survival; to the contrary, their survival was shortened. Moreover, tumor incidence in the post-treated group was not significantly different from the control but significantly increased in comparison to the pretreated group. Enhanced lung tumor growth resulted in a final tumor burden about twice that of untreated controls (P less than 0.05).