Thermoradiotherapy with interstitial thermoseeds in the treatment of localized prostate cancer. Initial results of a phase II study

Several experimental data are available regarding the efficacy of the combi nation of interstitial hyperthermia and conformal radiation therapy. We pla nned a phase II trial as a member of the special hyperthermia research grou p of the Deutsche Forschungs-gemeinschaft (German Research Society) to dete rmine the efficacy of thermoradiotherapy using interstitial cobalt-palladiu m thermoseeds in the treatment of patients with localized prostate cancer. Forty-one patients with localized prostate cancer were enrolled in the stud y between July 1997 and April 2000. The interstitial hyperthermia induced i n 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 temperat ures between 42 degrees and 46 degreesC. No major side effects were observe d during the hyperthermia session. The median level of prostate-specific an tigen (PSA) decreased from 11.25 ng/ml to 0.88 ng/ml 3 months after treatme nt and to 0.38 ng/ml 12 months after treatment with a median follow-up of 1 0 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 prosta te cancer therapy. A significant PSA decrease was observed. longer follow-u p is necessary to determine the efficacy.