Experimental approaches for the treatment of murine B16 melanomas of various sizes. II: Injection of ethanol with combinations of beta-interferon and microwaval hyperthermia for B16 melanomas with a size of greater than 10 mm in diameter.

Although ethanol injection in combination with microwaval hyperthermia and systemic administration of interleukin-2 was found to be very effective in suppressing the growth of B16 melanoma nodules with a size of less than 7 mm in diameter in our previous experiments, the growth of B16 melanomas with a size of greater than 10 mm in diameter was very difficult to control with any of the therapeutic modalities examined. In subsequent experiments, we investigated whether ethanol injection (150 microliters/injection) in combination with local injection of beta-interferon (2 x 10(4) IU/injection) and local microwaval hyperthermia at 43 degrees C for 15 min was able to suppress the growth of melanoma nodules and to prolong survival times of melanoma-burdened mice. The results were that we successfully suppressed the growth of melanoma nodules of that size for the first time with combinations of the therapeutic modalities described above. Infiltration of immunocompetent cells such as T lymphocytes and NK cells was clearly observed in the melanoma tissues treated with the therapeutic combination. These experimental results should be applied to the treatment of human melanomas in advanced stages which have no indications for surgical operation.