Evaluation of BCG administered by scarification for immunotherapy of metastatic hepatocarcinoma in the guinea pig

In inbred guinea pigs, administration of Mycobacterium bovis strain BCG by scarification at a site distant from an excised skin tumor, but in the regional lymph node drainage, was evaluated for its immunotherapeutic effect on the development of lymph node metastases. Scarification was performed after surgical excision of intradermally transplanted syngeneic (line-10) hepatocarcinoma at a time when microscopic foci of tumor cells were present in regional lymph nodes. Various strains of BCG were evaluated for their immunotherapeutic potential: fresh-frozen Phipps, Pasteur, and Tice; and lyophilized Pasteur, Tice, and Connaught. Scarification commenced 3 days after surgical removal of the tumor and continued once a week for 5 weeks. Only lymph nodes from fresh-frozen Phipps- and Pasteur-scarified animals were significantly smaller than those in the control groups. Differences in lymph node weight correlated histologically with less detectable metastases. This cytostatic effect was short lived; eventually, the metastatic tumor growth was not significantly different from that of control animals. No significant differences were observed in mean survival time: All animals died as a result of metastases 3 months after tumor inoculation. These results demonstrated that limited scarification with BCG of certain strains temporarily inhibits the growth and proliferation of metastases in regional lymph nodes after removal of the primary tumor.