Single versus double preoperative intralesional BCG in 13762 mammary adenocarcinoma

Ninety Fischer 344 female rats were injected subcutaneously with a syngeneic 13762 mammary adenocarcinoma. In order to study if repeated doses of preoperative intralesional (IL) BCG were more effective than single doses of IL BCG, and whether the amount of tumor burden influenced the effectiveness of single and/or double doses of BCG, 40 rats had single tumor implants and 50 had double tumor implants. If tumor was allowed to grow for 22 days before resection, all animals eventually died from spontaneous disseminated metastasis (survival for rats with single tumor = 72.8 +/- 12.1 days; for those with double tumors = 63.3 +/- 14.0 days). For rats with single tumors, one dose of IL BCG given 11 days before resection of tumor results in 25% longterm cures. But repeated doses of IL BCG gave much better survival results (43% cures). For rats with two subcutaneous tumors, single doses of preoperative BCG was not effective. Double injections of BCG significantly improved survival results and achieved occasional long-term cures (25%) if the combined tumor volumes were relatively small.