Thermoradiotherapy using interstitial self-regulating thermoseeds: an intermediate analysis of a phase II trial

Thermoradiotherapy in the treatment of prostate cancer is based on a variety of experimental and clinical phase I data which have proven the synergistic effects of this combination. We report on a phase II trial in a special hyperthermia research group (SFB 273) of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) to determine feasibility, acute toxicity and efficacy of this combination for prostate cancer.

57 patients with localized prostate cancer were treated with interstitial hyperthermia using cobalt-palladium thermoseeds and conformal radiation between July 1997 and December 2000. Thermoseeds were placed into the prostate homogeneously. Hyperthermia was created using a magnetic field and was delivered in six sessions once weekly for one hour. 3D-conformal radiotherapy of 68.4Gy was given simultaneously in daily fractions of 1.8Gy.

Intraprostatic temperatures were between 42 and 46 degrees C. No major side effects were observed during hyperthermia. Median follow-up was 36 months (range 3-72 months). Median PSA value decreased from 11.6ng/ml to 2.4ng/ml 3 months after treatment, to 1.3ng/ml 12 months after treatment and to 0.55ng/ml 2 years after therapy.

Interstitial hyperthermia is feasible, well tolerated and led to a steep decrease of PSA values. Combining effective interstitial hyperthermia with conformal radiotherapy may be an exciting innovative treatment option for prostate cancer.