Deep local and regional hyperthermia with annular phased array

33 refractory tumors mainly located in the pelvic cavity after definitive treatment were treated by loco-regional hyperthermia alone (n = 11) or by heat in combination with radiotherapy (n = 22) by annular phased array (APA) manufactured by BSD Corp. Tumors were heated up to more than 42 degrees C in 78% of 347 total heat sessions with induction time 22 +/- 1 (S.D.) minutes during which those of intra-pelvic organs were elevated up to between 41 and 42 degrees C. Tumor response was CR 18%, PR 50% by heat (11.2 +/- 1.5 S.D. fractions) combined with radiotherapy (43.8 +/- 12.5 S.D. Gy) and by heat alone (8.6 +/- 1.3 S.D. fractions) CR 18%, PR 9%. In all heat sessions superficial pain 36%, skin burn (grade 1-2) 12% inside annular array and slight to moderate systemic heat stress 100% were the main adverse reactions we experienced.