PO-0981: First experiences with combined EBRT and HDR-brachytherapy boost using Co-60 in patients with prostate cancer
B. Polat, Marco Parczyk, Sebastian Aeffner, M. Metz, Gabriele K. Beckmann, Otto Andreas Sauer, Matthias Gückenberger, Michael P. Flentje · Radiotherapy and Oncology · 2013
Purpose/Objective: To evaluate the first clinical and dosimetry data of a new afterloading machine using a Co-60 source.Materials and Methods: Patients with prostate cancer were treated by combined external beam radiotherapy (EBRT) followed by a brachytherapy boost: After 46Gy EBRT to the prostate two fractions of 9 Gy were applied, each 2 weeks apart.In 2008 a new afterloading machine (Multisource ® , Eckert & Ziegler BEBIG, Germany) was installed using a Co-60 source.Toxicity data were compared to a cohort of 131 patients treated with Ir-192 and the same fractionation scheme at our institution from 2001 -2008.Results: A total of 117 patientswere treated with Co-60 from 01/2008-10/2012.Median age at diagnosis was 72 years.Patients had a mean PSA value of 25.5 ng/ml and a mean Gleason-score of 7.2 ( 8: 19%).High risk tumours were present in 53%, intermediate risk in 42% and low risk in 5% of the patients.Neo-/adjuvant antihormonal therapy was given in 38.2%.Mean prostate volume was 31.7ml and mean IPSS was 7.4 at presentation.DVH parameters (mean values) for brachytherapy were D90: 8.97 Gy, COIN: 0.68.Dmax for rectal wall was 8.0 Gy and 11.8 Gy for the urethra.The TRAK value was 0.27 cGy x m 2 .Toxicities were evaluated according to CTCAE v3.0.Most frequent acute GU toxicities were an increase in urinary frequency (49%, 19.6% and 5.9%, grade I / II / III), painful voiding (45%, 4% and 4%, grade I / II / III) and urinary bleeding after interstitial brachytherapy (36.5% and 11.5%, grade I / II).Acute GI toxicity presented with proctitis (12% and 6%, grade I / II) and diarrhea (14% grade I).No acute grade IV toxicity was reported.Late toxicities are not presented because of the short follow-up (median 13.7 months).In comparison with the patients formerly treated with Ir-192 no significant increase in acute adverse events were reported (39.2% vs. 29.8%for grade II and 9.8% vs. 5.3% for grade III, Co-60 vs. .The comparison of the dosimetry data is still under evaluation and will be presented at the meeting.Conclusions: Using Co-60 for a HDR-brachytherapy boost after EBRT is a feasible technique in prostate cancer patients with no excess of toxicities in regard to Ir-192.Due to the short follow-up long term data on clinical outcome have to be awaited.