ESTRO 2023 - Abstract Book

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ESTRO 2023

during the first year after treatment and each 4-6 months during the following years. Acute and late toxicities were assessed according to the RTOG scale. Results The median follow-up was 49.50 months (IQR 34.29-61.56). Gleason score was 2+ 3 in one case, 3+3 in 7, 3+4 in 13 and 4+3 in 13 cases. Local stage was T1 in 6 cases, T2a in 9, T2b in 8 and T2c in 11 cases. Median time of ADT was 6 months (IQR 6.0-9.0). The initial median PSA level was 10.36 ng/ml (IQR 6.90-14.00), median nadir PSA level was 0.034 ng/ml (IQR 0.004 – 0.099). The estimated 5-year biochemical failure-free survival (BFFS) was 88.5 %. There was no statistically significant impact of ADT on BFFS (p=0.96). Acute grade 3 toxicity (hematuria needing catheterization) occurred in one patient. There was no other acute nor late higher than grade 2 toxicity.

Conclusion LDR-BT may be an effective option for selected IUR prostate cancer patients. There is a place for prospective studies to fully establish this method's effectiveness in treating IUR prostate cancer.

PO-2195 Two implant-fraction HDR-brachytherapy for prostate cancer: preliminary results and early toxicity

I. Strouthos 1,3 , K. Ferentinos 1,3 , E. Karagiannis 1,3 , G. Antorkas 2 , A. Antoniou 2 , Y. Roussakis 2 , N. Zamba 1 , E. Georgiou 1

1 German Oncology Center, Department of Radiation Oncology, Limassol, Cyprus; 2 German Oncology Center, Department of Medical Physics, Limassol, Cyprus; 3 European University Cyprus, Faculty of Medicine, Nicosia, Cyprus Purpose or Objective To analyse preliminary results in regard to early toxicity and urinary symptomatology of a two-implant-fraction high dose rate (HDR) brachytherapy (BRT) protocol used as monotherapy for clinically localised prostate cancer. Materials and Methods A retrospective analysis was conducted on 65 patients previously treated with HDR brachytherapy for prostate between April 2020 and April 2022. Patients received two fractions of 14 Gy, volume up to a total physical dose of 28 Gy with 7 days being the interfractional interval. The procedure was carried out using a transperineal approach and transrectal ultrasound- guided planning with fusion of MRI imaging acquired at the day of the procedure. Acute toxicity was evaluated both in regard to genitourinary and gastrointestinal systems using Radiation Oncology Therapy Group/European Organization for Research and Treatment of Cancer (RTOG/EORTC) grading and urinary symptomatology with International Prostate System Score (IPSS). Results The mean age was 69 (range: 49-81) years. The cohort comprised of 24 (37%) low, 35 (54%) favourable intermediate, 5 (8%) unfavourable intermediate and one (2%) high risk stratified according to National Comprehensive Cancer Network guidelines (NCCN). Androgen deprivation therapy duration was administered accordingly, based on risk group, with a total of 4 patients receiving ADT. A mean iPSA of 7.80 ng/ml (range: 1.50 - 21.0 ng/ml) and a mean prostate volume of 46.2 cubic centimeters [range: 22.4 - 99.3 (cc)] were also reported. In regard to early acute GU toxicity, 5% grade 2 and 2% grade 3 was noted at 3 months. No grade 2 or 3 acute GI toxicity was observed. Based on IPSS score, 15 patients (24%) experienced a worsening of the urinary symptomatology compared to baseline, with 38% of patients experiencing mild, 54% moderate, and 8% severe symptoms. Conclusion Our preliminary findings further support the use of HDR BRT as monotherapy for clinically organ-confined prostate adenocarcinoma and indicate that this radiotherapeutic protocol is accompanied with a favourable early toxicity profile.

PO-2196 Dosimetric results of a randomised trial of HDR vs. LDR single dose BT of localised prostate cancer

G. Fröhlich 1 , P. Ágoston 1 , K. Jorgo 1 , T. Major 1 , Z. Takácsi-Nagy 1 , C. Polgár 1

1 National Institute of Oncology, Centre of Radiotherapy, Budapest, Hungary

Purpose or Objective