Intratumoral BCG therapy of transplanted head and neck tumors in strain 2 guinea pigs.

The generally unfavorable prognosis associated with advanced squamous cell carcinoma in the head and neck region in humans led us to immunotherapeutic experiments with bacillus Calmette-Guerin (BCG) in inbred guinea pigs with solid growing and lymphogenous metastasizing tumors. The injection of live BCG or BCG cell wall preparation (CWP) into the planum buccale in the guinea pig led to a pronounced local inflammatory reaction. If live BCG or BCG CWP were injected into the planum buccale together with line 10 tumor cells, no growth of the tumor could be observed. Animals treated in this manner developed a tumor-specific immunity. Guinea pigs treated intratumorally with live BCG or BCG CWP in established, 6-day-old tumors of the planum buccale showed regression of the primary tumor and prevention of the development of lymph node metastases. These cured animals also developed a tumor-specific immunity. Guinea pigs with 6-day-old tumors of the planum buccale remained tumor free after surgical removal of the primary tumor and the draining submandibular and cervical lymph nodes (radical operation) whereas locally operated animals (primary tumor excision) developed lymph node metastases. Animals that were tumor free after radical surgery did not develop tumor-specific immunity. Despite insufficiently clarified mechanisms for the induction and effect of BCG immunotherapy, we can state that, with intratumoral BCG therapy, a tumor experimentally placed in the head and neck region is eliminated, regionally manifest metastases are eliminated, and specific tumor immunity can be demonstrated in successfully treated animals.