Intraoperative dosimetry planning does not improve the postoperative dose coverage after LDR - brachytherapy - a prospective clinical study

521 INTRAOPERATIVE DOSIMETRY PLANNING DOES NOT IMPROVE THE POSTOPERATIVE DOSE COVERAGE AFTER LDR BRACHYTHERAPY -A PROSPECTIVE CLINICAL STUDY Siegsmund Alken P.’

M.‘, Musial A.‘, Grieger

J.‘, Trojan L.‘, Michel MS’,

‘University Hospital, Urology, Mannheim, Radiation Oncology, Mannheim, Germany

Germany,

‘University

Wenz F.‘,

Hospital,

INTRODUCTION & OBJECTIVES: Implantation of permanent iodine 125 seeds evolves as a alternative treatment modality in localized prostate cancer. In order to get optimal results stringent patient selection is mandatory, besides that recent data show, that the dose covering 90% of the target volume (D90) is very important. Implants achieving a D90 of more than 90% of the prescribed dose produce better results than implants with a D90 of < than 90%. To achieve these high D90 values, some centers favour intraoperative planning instead of preplanning 4 weeks before the implantation. This study was undertaken to evaluate if intraoperative planning improves the dose coverage 6 weeks after implantation. MATERIAL & METHODS: 40 patients were prospectively randomised in 2 groups. 19 patients of group 1 had preoperative planning of seed distribution 1 day before implantation. In 21 patients of group 2 the treatment plan was performed within the treatment session. We recorded the time that was necessary for each step of planning, loading and implantation. After 6 weeks a CT-based dosimetry was performed, and D90 (dose covering 90% of the target volume) and VlOO (target volume covered with 100% of the prescribed dose) were calculated. RESULTS: Prostate volumes and seed number did not differ significantly. Total operation time was more than doubled with intraoperative planning compared to preplanning (110.5 min. vs. 54.4 min). D90 and VI00 values 6 weeks after implantation did not differ significantly in both groups (D90 group 1: 120.60/o, group 2: 116.4%; VI 00 group 1: 96. I%, group 2: 94.5%). There was no difference in number or intensity of postoperative complications. CONCLUSIONS: With preplanning the implantation time and anaesthesia time can be reduced significantly, without any impairment of dose coverage. lntraoperative planning is not useful in pennanent seed implantation.

522 HIGH DOSE RATE BRACHYTHERAPY CANCER

OF LOCALIZED

PROSTATE

Deeer S.‘, Bohmer D.‘, Roigas J.‘, Turk I.‘, Budach V.‘, Loening S.’ ‘Charrte Hospital, Urology, Berlin, Germany, ‘Charite Hospital, Radiation-Oncology, Berlin, Germany

Campus Mitte,

INTRODUCTION & OBJECTIVES: We evaluated the safety and efficacy of high dose rate (HDR) brachytherapy using Iridium-192 (Ir 192) and 3D conformal external beam radiotherapy in patients with localized prostate cancer. MATERIAL & METHODS: A total of 444 patients with localized prostate cancer underwent combined radiotherapy with interstitial Ir 192 and 3D conformal external beam radiotherapy between December 1992 and March 2001. 230 patients, treated between December 1992 and December 1997 were analysed. All patients underwent laparoscopic pelvic lymph node dissection to exclude patients with lymphatic involvement. Ir 192 was delivered twice with a l-week interval in HDR remote control technique. The interstitial dose from December 1992 to December 1993 was IOGy, after December 1993 the dose was reduced to 9Gy per treatment session. The interstitial application was followed by external beam radiation of 45Gy for cTl-cT2 and 50.4Gy for cT3 tumour (ilOGy from December 1992 to December 1993). Progression was defined as biochemical failure according to ASTRO criteria, e.g. three consecutive PSA rises following the PSA nadir. RESULTS: The median PSA value decreased from initial 12.8 to 0.47 ng/ml 24months after treatment. Median PSA value was 0.30ng/ml after 36 months and 0. I Xng/ml after 60 months. 68% of the biopsies were negative 24 months after therapy. Progression-free rate was 100% for CT 1 tumours, 75% for cT2 and 60% for stage-CT3 on 5-year follow-up. Five-year overall survival was 93%, 5-year disease-specific survival was 98%. CONCLUSIONS: Combined HDR brachytherapy with Ir 192 is an alternative treatment option especially for patients with cT3 prostate cancer. Initial PSA value. stage and grade, are important prognostic factors.

523 COMPARISON TECHNIQUES;

OF TWO IODINE-125 BRACHYTHERAPY PREPLANNING & INTRA-OPERATIVE

Matzkin H.‘. Kaver I.‘. Bramante-Schrieber

IMPLANT

L.‘. Agai R.‘, Inbar M.’

‘Tel Aviv Medical Center, Urology, Tel Aviv. Israel, ‘Tel Aviv Medical Center, Pathology, Tel Aviv, Israel. ‘Tel Aviv Medical Center, Oncology, Tel Aviv, Israel INTRODUCTION used in prostate techniques.

& OBJECTIVES: Several implant methods are currently iodine-125 brachytherapy with no comparison between

MATERIAL & METHODS: We report the results of detailed one-month postoperative dosimetric evaluation and comparison between 142 consecutive men with prostate cancer treated by pre-planning methodology followed by 164 men treated with rcal-time, intra-operative iodine-125 brachytherapy. CT-based quality assessment parameters were correlated with short-term early postoperative morbidity. RESULTS: Length of physicist time and OR team ttme was more than double in the pre-planned group as compared to the intra-operative one. Based on day 30 post- implant CT, for patients treated with pre-planning methodology. mean V90, VI00 and VI50 were 67.5%, 58.3% and 21.5%, while for the intraoperative group they were 97.9 %, 95.2% and 45% respectively (p
524 RE-IMPLANT FOR AFTER PERMANENT

INADEQUATE POST-IMPLANT PROSTATE BRACHYTHERAPY

Nava L.‘. Losa A.‘, Dell’Acqua Guazzoni G.‘. Rtgatti P.‘

E.‘, Cestart A.,, Zanoni

‘Ville Turro - San Raffaele Hospital. Hospital, Urology, Milan. Italy

Urology,

Milan,

DOSIMETRY

M.‘, Centemero

Italy, San

A.‘,

Ratfaelc

INTRODUCTION & OBJECTIVES: Btochemical outcome after prostate brachytherapy (BT) is strictly correlated to the effective dosimetric coverage of the entire prostate volume. The attainment of this goal is related with the experience and learning curve of the team: what should be done in the event of an inadequate implant is still debated. Re-treatment could be an effective tool for completing an implant when a well-defined cold area is detected after postimplant dosimetry. MATERIAL & METHODS: Three of our patients (31136) with low risk prostate carcinoma underwent BT, during team’s learning curve, as primary therapy with a prescription dose of 135 Gy, using 103 Pd loose sources. The subsequent MRI - based post planning revealed unsatisfactory dosimetrical outcomes with a well-defined cold area. In two patients the underdosage at the base of the gland was caused by an exaggerated traction on the stabilizing needles; in the third patient the anterior, transitional area was “cold” because of the migration of many seeds along a dilated dorsal vein complex. We considered the cold area as the target for the second implant and planned to deliver the same prescribed dose as a monotherapy. RESULTS: All three (VlOO >94%), and an were comparable with up (32 months) does however all 3 patients effect.

patients reached a global therapeutical dose coverage optimal dosimetty at the re-treated area. The side effects those experienced by our BT patients. The short follownot allow us to draw any final oncological outcome: reached a PSA nadir 10.2 ng/ml reflecting a therapeutic

CONCLUSIONS: ‘This is the first experience reported in literature about reimplant after BT, in selected cases with well - defined cold area. Re-implant is technically feasible, safe and can be an option to reach an optimal dosimetric coverage and therapeutical effectiveness. European

Urology Supplements 2 (2003) No. 1, pp. 133