[Experimental studies on effects of total-body and local hyperthermia on metastases in mice]

To study the effects of total-body hyperthermia (TBH) and local one (LH) on tumor metastases in animal experiments, heat was delivered to Lewis lung carcinoma (LLC)-bearing C57BL/6 mice and mouse ascites hepatoma-134 (MH-134)-bearing C3H/He mice, by water bath immersion systemically and locally. Rectal temperature in TBH was kept at 40 or 42 degrees C, while intratumor temperature in LH, at 40, 42, or 43 degrees C, respectively for 30 min. Also backgrounds of spread of lung metastasis of LLC in the case of TBH at 42 degrees C have been investigated as well as strategic preventive measures for it. The following results were obtained: The growth of primary LLC and MH-134 tumors was inhibited by TBH and LH at 42 degrees C and LH at 43 degrees C. The lung metastases of LLC increased by TBH at 42 degrees C. The lymph node metastases of MH-134 decreased by LH at 43 degrees C. The increase of lung metastases of LLC by 42 degrees C TBH occurred within 24hr after the session, presumably due to the increase in intravascular invasion of tumor cells and accelerated implantation of them according to histological changes of lungs. The observable tendency toward lung metastases continued for 48hr after treatment, coincidentally with distinctness in observation of histological changes. The increase mentioned above could be prevented by combined use of 42 degrees C TBH with anticancer drugs, as cis-diamminedichloroplatinum II or mitomycin-C. This combination resulted in further inhibition of tumor growth of primary LLC also, than non-combined 42 degrees C TBH. Considering the above facts, combined treatment of TBH with anticancer drugs is believed much valid clinically, in preventing metastases and making higher exertions of antitumor effects.