The acceleration of metastasis after excision of the main malignant tumor and the worsening of the prognosis are sometimes experienced. This phenomenon was simulated in model experiments using Lewis lung carcinoma (3LL) cells and BDF(1) mice. The change of cell-mediated immunity was also studied using delayed type hypersensitivity (DTH) skin reaction. For the purpose of getting a better prognosis, preoperative intratumoral administration of large doses of the immunostimulant OK-432 and splenectomy were studied as possible adjuvant therapy to surgical treatment. Pulmonary metastases and their growth were accelerated after excision of the main subcutaneous tumor, and as a result survival time was not extended. However, DTH increased after the operation. Splenectomy in the early stage was significantly effective on survival, increase of DTH and growthinhibition of the main tumor. The optimum dose of OK-432 in intratumoral administration was 10KE/mouse, and a significant effect was obtained on survival, increase of DTH and growth-inhibition of the main tumor with this dose. Preoperative intratumoral administration of OK-432 and splenectomy in the early stage were useful adjuvant therapy to surgical treatment. A significant effect was obtained on suppression of pulmonary metastases, increase of DTH and survival.
delayed type hypersensitivity