At least eight studies in recent years have shown that adding hyperthermia to chemotherapy or radiation can improve local control of cancers of the esophagus, cervix, head and neck, brain and melanoma and breast cancers that have spread to the chest wall, said Dr. Mark Dewhirst, director of the hyperthermia program at Duke University Medical Center in Durham, N.C.

Scientists who have observed firsthand the effects of hyperthermia are impressed. "I'm amazed at some of the tumors that just melt away with the combination of radiation and heat," said Dr. David Wazer, chief radiation oncologist at Tufts-New England Medical Center in Boston.

Among the studies turning the tide for hyperthermia is one published last year by Dr. Ellen L. Jones, a Duke radiation oncologist. Writing in the Journal of Clinical Oncology, her team reported that, compared with patients getting radiation but not hyperthermia, those who got both had a significantly reduced risk of recurrence of "superficial" tumors, chiefly breast cancers that had spread to the chest wall.