Regional hyperthermia combined with high energy shock wave treatment on Dunning prostate tumors

Male Copenhagen rats implanted with Dunning R3327 prostate carcinoma were treated with regional hyperthermia and high energy shock waves (HESW). Twenty-four rats were divided into four equal groups. All rats in one group were matched with the corresponding rats in the other three groups according to tumor size. Hyperthermia was created by the resistive heating of a 22-gauge 1.5-cm needle; HESW were generated by the Dornier XL-1 experimental lithotripter. In two hyperthermia treatments administered 48 hours apart, the tumor was heated to 46.5 degrees C for 2 hours; HESW treatment involved 1,600 shocks at 18 kV. Twenty-nine days after initiation of this study, animals were sacrificed and tumor growth calculated. Tumor growth in group 1 (combined hyperthermia and HESW) was significantly delayed between the 7th and 29th day (p = 0.05). In group 2 (HESW alone), tumor growth was significantly delayed between the 7th and 22nd day (p = 0.01), while tumor growth in group 3 (hyperthermia alone) was delayed between the 3rd and 22nd day (p = 0.02). On day 22, mean percent change in tumor growth in the control group exceeded that of group 1 by 449% (p = 0.015) as well as that of groups 2 and 3, by 350% (p = 0.034) and by 268% (p = 0.049), respectively. As previous reports demonstrate the efficacy of hyperthermia in combination with irradiation or chemotherapy for the treatment of prostate carcinoma, our results indicate hyperthermia in combination with HESW may also be a useful treatment modality.