[Thermoradiotherapy with interstitial thermoseeds in treatment of local prostatic carcinoma. Initial results of a phase II study].

Several experimental data are available regarding the efficacy of the combination of interstitial hyperthermia and conformal radiation therapy. We planned a phase II trial as a member of the special hyperthermia research group of the Deutsche Forschungsgemeinschaft (German Research Society) to determine the efficacy of thermoradiotherapy using interstitial cobalt-palladium thermoseeds in the treatment of patients with localized prostate cancer. Forty-one patients with localized prostate cancer were enrolled in the study between July 1997 and April 2000. The interstitial hyperthermia induced in a magnetic field was applied in six sessions once a week. Conformal three-dimensional radiation therapy was given simultaneously in daily fractions of 1.8 Gy with a total dose of 68.4 Gy. We measured intraprostatic temperatures between 42 degrees and 46 degrees C. No major side effects were observed during the hyperthermia session. The median level of prostate-specific antigen (PSA) decreased from 11.25 ng/ml to 0.88 ng/ml 3 months after treatment and to 0.38 ng/ml 12 months after treatment with a median follow-up of 10 months. The mean prostate volume decreased from 32.6 ml to 26 ml after 3 months of treatment and to 18.5 ml after 12 months. Interstitial hyperthermia is a feasible, well-tolerated procedure in prostate cancer therapy. A significant PSA decrease was observed. Longer follow-up is necessary to determine the efficacy.