RF Capacitive Hyperthermia for Malignant Pelvic Tumors

Abstract

36 patients with inoperable malignant pelvic tumors were treated by local hyperthermia combined with radiotherapy. The purpose of this study is to evaluate the thermometry results and the antitumor effects of this treatment.
The 36 patients consisted of 14 colorectal cancers, 6 uterine cancers, 7 metastatic bone tumors, 5 urinary bladder cancers and 4 ovarian cancers. Hyperthermia was performed by 8 MHz RF capacitive heating equipment, once or twice a week after irradiation, four to 10 sessions in total. All cases underwent radiotherapy (total dose, 2050Gy), and 14 patients received combination chemotherapy in an addition to radiothermotherapy.
20 (55.6%) of the 36 patients could undergo intratumor thermometry by direct puncture. In 8 cases (40.0%) of these 20 patients, the maximum tumor core temperature (Tmax) could be elevated to more than 42°C, and the mean Tmax was 41.7± 0.3°C (40.044.7°C). There was a significant correlation between Tmax and electric output during heating. Any tumors could not be heated to more than 42°C using electric output under 600 watt. And electric output was limited by a painful sensation due to overheating of subcutaneous fat tissue.
The local response rate based on tumor regression of all cases was 38.9% (CR 1, PR 13, NC 22). The tumor response was dependent on Tmax and the tumor size. The response rate was fairly higher in the higher Tmax (≥ 42°C) group than the lower Tmax (< 42°C) group (75% vs 25%). And greater response was observed in small tumors. On the contrary, large tumors over 10cm in diameter tended only to become necrotic, but not to become smaller.
There was no clinically severe complication associated with hyperthermia in this trial. So this combination therapy is a very promising therapeutic modality for unresectable malignant pelvic tumors.