Phase I/II study of external radio frequency phased array hyperthermia and external beam radiotherapy in the treatment of prostate cancer: technique and results of intraprostatic temperature measurements.

As part of an ongoing Phase I/II study at Duke University Medical Center investigating the toxicity and efficacy of external beam radiotherapy plus hyperthermia for deep-seated, locally advanced or recurrent solid tumors, 12 patients with prostate malignancies (adenocarcinoma--11, leiomyosarcoma--1) were treated with radiotherapy plus hyperthermia. Hyperthermia was given after radiotherapy using a Radio Frequency Phase/Amplitude Control Sigma 60 annular phased array device. All patients had simultaneous temperature measurements made in the rectal lumen and within the prostate during at least one hyperthermia session. Intraprostate thermometers were placed via a unique method described herein using both computerized tomography scan and a rigid sigmoidoscope for guidance. We were able to achieve the desired tumor temperature of > or = 42.5 degrees C in only 1/28 (3.5%) of hyperthermia treatments. Subjective symptoms of pain and/or pressure limited power deposition in 79% of hyperthermia treatments. Higher temperatures were achieved in the distal rectum than in the prostate in all treatments, although the differences were not statistically significant. This temperature differential could not be compensated by using phase and amplitude steering. Rectal temperatures adjacent to the prostate were predictive of prostate temperatures. We conclude that using this regional heating technique we were unable to demonstrate an ability to get an advantageous temperature differential between the prostate and normal tissue. This technique is not useful as an adjuvant to radiation therapy for prostate cancer. The usefulness of other regional heating techniques and devices should be explored.