Regional hyperthermia for clinically advanced deep-seated pelvic malignancy.

Forty-three patients with deep-seated pelvic malignancy have been treated at the University of Utah on a pilot protocol involving regional hyperthermia (HT) produced by the BSD-1000 HT system and the annular phased array applicator (AA) usually driven at 60 MHz. Acute toxicity consisted primarily of pain within the AA aperture (74%), pain outside the aperture (33%), and bladder spasm (26%) or systemic stress (25%). Systemic stress only infrequently was power limiting. The most common power-limiting factors were pain (33%) and excessive heating of normal tissues (23%). In 9 patients (21%), there was no power-limiting factor. Treatment-related complications were uncommon and consisted of superficial second degree burns (3 patients), small bowel obstruction (1 patient), and rectal fistula (1 patient), all of which resolved with supportive nonsurgical therapy. Detailed thermal mapping and thermal dosimetry were performed on 36 patients. Thermal dosimetry parameters were all rather disappointing; however, the protocol prioritized the prevention of complications, and patients with acute toxicity or other power-limiting factors were not pushed to achieve high thermal doses. A logistic regression analysis was performed to determine if any factors were correlated with response (PR + CR). "Concurrent radiation dose" and "number of satisfactory heat treatments" were highly and independently correlated with response (p = 0.002). Responders (median survival = 10 months) survived significantly longer (p = 0.0014) than nonresponders (median survival = 4 months). Four of the responders are alive and currently without evidence of disease.