The effect of radiofrequency hyperthermia on the Ca755 murine adenocarcinoma.

Radiofrequency (RF) was used to induce hyperthermia in the Ca755 murine adenocarcinoma. Thermal kinetic studies revealed a selective heating of tumors over normal tissues during RF, which occurred in larger but not smaller tumors. Small tumors required a significantly greater RF output than did larger neoplasms for heating to the tumoricidal range of 42 C. Rates of tumor growth were not changed after single RF treatments at 42 C, but tumors receiving three applications of RF were significantly smaller than a control group at 28 days tumor age. RF may be of value in the treatment of large neoplasms by using multiple applications; however, microscopic mitoses may not be affected directly without simultaneously damaging normal tissues in the RF field.