Immunotherapy of bilateral lymph node metastases in guinea pigs by intralesional or paralesional injection of Mycobacterium bovis (BCG).

Bilateral axillary lymph node metastases occurred after intradermal (id) injection of line 10 hepatocellular carcinoma cells over the thoracic spine of inbred guinea pigs. Excision of the dermal tumor 7 days after injection of tumor cells did not prevent the development of metastases. Injection of BCG into dermal tumors without surgery led to their regression and prevented the growth of microscopic metastases in both right and left superficial distal axillary lymph nodes. Bilateral id injection of BCG between the dermal transplant and each of the regional lymph nodes followed by excision of the dermal tumor also prevented progression of metastases. Unilateral id injection of BCG before excision of dermal tumors failed to retard metastases in contralateral superficial distal axillary lymph nodes. These results suggested that elimination of microscopic lymph node metastases required delivery of adjuvant to or near each metastatic site. Systemic tumor immunity alone may be inadequate to eradicate lymph node metastases.