Experimental approaches for the treatment of murine B16 melanomas of various sizes. I: Local injection of ethanol with a combination of interleukin-2 or microwaval hyperthermia for B16 melanomas with a size of less than 7 mm in diameter.

The effects of local absolute ethanol injection combined with administration of interleukin-2 (IL-2) or microwaval hyperthermia in murine B16 melanomas with a size of approximately 7 mm in diameter were investigated. The groups of melanoma-burdened mice treated with both local ethanol injection and local or intra-abdominal administration of IL-2 showed clear suppression of any recurrence of melanoma once the melanomas had been destroyed by ethanol injection and a concomitant prolongation of the survival times. Also, local injection of ethanol in combination with local microwaval hyperthermia at 43 degrees C for 15 min twice a week caused complete cures in B16 melanomas with a size of less than 7 mm in diameter. The infiltrations of T lymphocytes and NK cells were augmented in the melanomas treated with ethanol injection and local injection of IL-2. However, the melanomas treated with ethanol injection and intra-abdominal injection of IL-2 hardly showed any infiltration of such immune cells, although the growth of melanomas was effectively suppressed. In the case of treatment with ethanol and hyperthermia, slight infiltration of NK cells was observed in the melanoma nests as well as in the interstitials. Thus, the direct injection of absolute ethanol in combination with IL-2 or microwaval hyperthermia is effective or even curative in the treatment of murine B16 melanomas with a size of less than 7 mm in diameter.