BCG immunotherapy: effects of dose and route of administration on survival of mice bearing established tumors.

Bacillus Calmette-Guérin (BCG) was administered in various doses by four different routes to C3H/HeJ mice bearing well-established syngeneic MC-42 fibrosarcomas. Injections of BCG into established primary tumors decreased survival of tumor-bearing mice as compared to saline-injected controls. Of the three dosage groups, high-dose (10(8) viable organisms) intralesional BCG was most detrimental. The injection of low-dose BCG (10(4) organisms) into established tumors or subcutaneously at a distant site also shortened host survival times. Other subcutaneous injections and injections of BCG into the peritoneal or pleural cavities had no significant effect on survival, regardless of dosage. The dose-dependent effects of BCG immunotherapy which may prolong or shorten survival are discussed.