3D interstitial HDR brachytherapy combined with 3D external beam radiotherapy and androgen deprivation for prostate cancer - Preliminary results

Background: Evaluation of feasibility, tolerance and efficiency for a new 3 D interstitial HDR brachytherapy technique combined with 3D external beam r adiotherapy and androgen deprivation for prostate cancer. Patients and Methods: Between January 1997 and August 1998 we treated 35 pa tients with Stage cT1-3 N0 M0 prostate cancer. Thirty-two patients with a f ollow-up of 12 to 28 months (median: 18 months) were evaluated. After ultra sound-guided transrectal implantation of 4 non-parallel needles, CT based 3 D brachytherapy treatment planning ("Offenbach system") was performed. All patients received 4 fractions brachytherapy using a fractional dose of 5 or 7 Gy, Time between each fraction was 14 days. After brachytherapy 3D exter nal irradiation followed up to 39.6 or 45.0 Gy. All patients received andro gen deprivation, starting 2 to 19 months before brachytherapy, ending 3 mon ths after 3D external radiotherapy. Results: Posttreatment PSA levels dropped to <1.5 ng/ml in 29/32 patients ( 91%). In 25 patients PSA levels were <0.5 ng/ml, in 4 patients 0.5 to 1.5 n g/ml. In 2 patients we noted biochemical relapse. Transrectal implantation was very well tolerated. Grade 3 acute urinary toxicity occurred in 1 patie nt. We noted no Grade 2 or higher acute gastrointestinal toxicity. One pati ent developed a Grade 3 late urinary toxicity. No patient showed late gastr ointestinal side effects. All 140 dose-volume histograms for 3D HDR brachyt herapy were analyzed. Conclusions: The new 3D HDR brachytherapy technique, combined with 3D exter nal irradiation and androgen deprivation, is a feasible, so far well tolera ted and effective treatment in the short-time follow-up of median 18 months .