Interstitial hyperthermia using self-regulating thermoseeds combined with conformal radiation therapy

Objective: The combination of hyperthermia and radiation in the treatment of malignancies is based on a variety of experimental data which have proven the synergistic effects of these two treatment modalities. We planned 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. Methods: A total of 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. 3D-conformal radiotherapy of 68.4 Gy was given simultaneously in daily fractions of 1.8 Gy. Results: Intra-prostatic temperatures were between 42 and 46 degreesC. No major side effects were observed during hyperthermia. Median follow-up was 12 months (range: 3-26 months). Median prostate specific antigen (PSA) value decreased from 11.6 to 2.4 ng/ml 3 months after treatment, to 1.3 ng/ml 12 months after treatment and to 0.55 ng/ml 2 years after the therapy. Conclusion: Interstitial hyperthermia is feasible, well tolerated and led to a steep decrease of PSA values. Our current follow-up is too short to comment about efficacy. Combining effective interstitial hyperthermia with conformal radiotherapy may be an exciting innovative treatment option for prostate cancer. (C) 2002 Elsevier Science B.V. All rights reserved.