Effects of total-body hyperthermia on metastases from experimental mouse tumors

To study the effects of total-body hyperthermia (TBH) on metastases from malignant tumors, Lewis lung carcinoma (LLC)-bearing C57BL/6 mice and mouse ascites hepatoma 134-bearing C3H/He mice were immersed in a heated water bath. Rectal temperature was maintained for 30 min at 40 degrees C or 42 degrees C. After treatment, the incidence of lung metastasis was analyzed in LLC-inoculated mice, and the presence or absence of metastasis in affiliated lymph nodes was determined in mouse ascites hepatoma 134-inoculated mice. A significant inhibition in primary tumor growth in LLC- and mouse ascites hepatoma 134-bearing mice treated with 42 degrees C TBH was noted. The incidence of lung metastasis was increased from the control level of 1.6 +/- 0.63 (SD) to 2.4 +/- 0.98 in the 42 degrees C TBH (P less than 0.01) groups but not in the 40 degrees C TBH group. Metastasis to affiliated lymph nodes was similar for the controls and the 40 degrees C and 42 degrees C TBH groups. The increase in lung metastasis in LLC-treated mice subjected to 42 degrees C TBH could be prevented by the combined use of anticancer drugs such as cis-diamminedichloroplatinum(II) (1.0, 3.0 mg/kg) or mitomycin C (0.3, 1.0 mg/kg). Furthermore, the combined use of 42 degrees C TBH and anticancer drugs showed the inhibition of primary tumor growth to a greater degree than did 42 degrees C TBH alone or anticancer drugs alone. Since 42 degrees C TBH may induce tumor metastasis, especially hematogenous metastasis, it seems advisable to use anticancer drugs in combination with clinical thermal applications.