ESTRO 2023 - Abstract Book

S234

Saturday 13 May

ESTRO 2023

measured separately and compared to the respective measurement on MRI. The expected implant quality for optimal dose prescription was rated with the following scoring system: 1=excellent (HR-CTV and organs at risk (OAR’s) soft constraints were met), 2=sufficient (HR-CTV or OAR’s soft constraints violated), 3=poor (HR-CTV and OAR’s soft constraints violated), 4=insufficient (HR-CTV and/or OAR’s hard constraints violated). Evaluation and measurements were performed by 3 radiation oncologists with more than 5 years of experience. Descriptive statistics were used for data analysis. Results Patient accrual began in 05/2022. By now, 11 patients with local FIGO stage IIB-IIIB with 20 applications and a total of 112 needles (94 straight through the ring, 12 oblique through the ring, 6 free-handed) were available. Overall, 110/112 needles (98.2%) were visible, mean visibility score ± standard deviation (SD) was 2.6 ± 0.7 for all visible needles. The two non- visible needles (both inserted free-handed) were masked by artefacts or outside the field of view. Maximum (max), minimum (min), mean ± SD distance of the visible needles to tandem was 35mm, 4mm, 17.4mm ± 4.0mm on MRI and 28 mm, 6 mm, 17.2mm ± 3.4mm on TRUS, respectively. Max and mean ± SD difference between MRI and TRUS was 4 mm, 1.1mm ± 1.0 mm. 3/110 needles (2.7%) had a difference of more than 3mm. Expected implant quality based on TRUS imaging and actual implant quality after MRI-based planning are compared in table 1.

Conclusion Almost all interstitial needles (98%) were visible on TRUS in this interim analysis. Needles inserted through the predefined applicator positions were always detectable. Qualitatively, the majority of needles showed a distinct signal on TRUS. The quantitative difference compared to MRI was within 3mm in 97%. The expected implant quality based on TRUS imaging was congruent with the actual MRI-based implant quality in the majority of cases. Implant quality was rather underestimated on TRUS in the non-congruent cases. MO-0299 Excellent long-term control with radioactive seeds in young patients with early prostate carcinoma J.L. Guinot 1 , V. Gonzalez-Perez 2 , M.A. Santos 1 , M.I. Tortajada 1 , C. Guardino 2 , J. Casanova 3 , M. Nuñez 1 , S. Canos 4 , V. Cotanda 2 , M. Vercher 4 , M.A. Vico 2 , L. Arribas 4 1 Foundation Instituto Valenciano de Oncologia (IVO), Radiation Oncology, Valencia, Spain; 2 Foundation Instituto Valenciano de Oncologia (IVO), Radiation Physics, Valencia, Spain; 3 Foundation Instituto Valenciano de Oncologia (IVO), Urology, Valencia, Spain; 4 Foundation Instituto Valenciano de Oncologia (IVO), Radiation oncology, Valencia, Spain Purpose or Objective There is a tendency to propose radical prostatectomy to young men with early prostate cancer due to long life expectancy. But surgery has side effects that can alter the quality of life. We have analyzed the long-term efficacy of permanent brachytherapy (BT) with real-time system and custom-linked 125-I seeds (QuickLink™, Bard Medical) in young men up to 60 years old. Materials and Methods Between December 2007 and May 2016 we have treated 154 men between 44 and 60 years old (median 57), 107 low risk, 26 intermediate favorable and 21 intermediate unfavorable. Median PSA was 6.37ng/ml (3.3-17.9). The clinical classification was: 113 T1c, 29 T2a, 5 T2b and 7 T2c; Gleason 3+3 in 137, Gleason 3+4 in 14, and Gleason 4+3 in 3; 15 patients had >50% positive biopsy cores. The treatment was exclusive seeds 145 Gy in 129 cases and combined external radiation 46Gy + BT 108Gy in 25 cases (51% of intermediate risk cases with combined treatment). Androgen deprivation therapy (ADT) was used in 11 cases (6 intermediate risk cases x 6 months, and 5 low risk cases x 3 months to reduce volume). The PSA control probability was calculated by the Kaplan-Meyer method. Results With a median follow-up of 96 months (24-159), only 3 biochemical relapses of PSA have appeared, two in low-risk cases and one in unfavorable intermediate. Ten-year biochemical relapse-free survival (BRFS) is 97.6% (at low risk 98.1%, at intermediate risk 95.8%, 100% favorable, 92.9% unfavorable). The differences are not significant by T (T1 99.1%, T2 93.7%) or by PSA level (98.5% < 10ng/ml, 97.3% >10) or by Gleason (G6 98.5%, G7 90.9%). Late complications appeared in 15%, urological in 13.6%, rectal in 1.9%, G2 4.5%, G3 4.5%. Temporary bladder catheterization was necessary in 7%, transurethral resection in 4.5%. Good or acceptable sexual function was preserved in most cases. Conclusion Real-time BT with custom-linked 125-I seeds offers excellent long-term BRFS results in men up to 60 years old. The rate of complications is low, and ADT was used in very few cases, since the preservation of sexual function is an important factor for young people. Therefore, brachytherapy with radioactive seeds should be considered as the first therapeutic option.

MO-0300 Salvage HDR interventional radiotherapy for prostate cancer after prostatectomy and irradiation