ESTRO 2022

Session Item

Saturday

May 07

16:55 - 17:55

Mini-Oral Theatre 1

07: Brachytherapy

Co-Chair: Elena Manea, Romania;

Chair: Maximilian Schmid, Austria

Session Code: 1570

Session Type: Mini-Oral

Track: Brachytherapy

Implementation of high-dose-rate brachytherapy as monotherapy for over-sized prostatic gland

Iosif Strouthos, Cyprus

Presentation Number: MO-0302

Abstract

Abstract Title:

Implementation of high-dose-rate brachytherapy as monotherapy for over-sized prostatic gland

Authors:

Yiannis Roussakis¹, George Antorkas¹, Anna Antoniou², Constantina Cloconi³, Efstratios Karagiannis^3,4, Konstantinos Ferentinos^3,5, Christakis Damianou², Iosif Strouthos^3,5

¹German Oncology Center, Medical Physics, Limassol, Cyprus; ²Cyprus University of Technology, Electrical Engineering, Computer Engineering and Informatics, Limassol, Cyprus; ³German Oncology Center, Radiation Oncology, Limassol, Cyprus; ⁴European University Cyprus, Medical School, Limassol, Cyprus; ⁵European University Cyprus, Medical School, Nicosia, Cyprus

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Purpose or Objective

Prostatic gland enlargement can be considered a contraindication for high-dose-rate (HDR) brachytherapy (BT). The current study aims to dosimetrically compare prostate HDR BT plans as a function of prostate volume (greater/less than 55 cubic centimetres (cc)), while at the same time evaluating gastrointestinal and genitourinary toxicity through patient reported outcomes (PRO).

Material and Methods

Fifty-three patients previously treated for prostate cancer with HDR brachytherapy as monotherapy (2 x 14 Gy) between January 2018 to February 2021 were retrospectively selected. Several dose volume histogram (DVH) statistics for prostate, urethra, rectum, and bladder have been calculated for each plan (two implants per case) and analysed in correlation to prostate volume. Additionally, PRO information was recorded using two validated questionnaires (a. RTOG/EORTC: Radiation Oncology Therapy Group/ European Organization for Research and Treatment of Cancer; b. IPSS: International Prostate System Score), with a baseline before treatment and repeats every 3 months following completion of treatment.

Results

The median prostate gland volume for the entire cohort (n = 53), <55cc cohort (n = 37), ≥55cc cohort (n = 16) was 48.7cc, 34.5cc and 78.8cc, respectively. Median follow up was 9 months. No statistically significant differences (p>0.05) were observed in DVH parameters D_90%, D_100%, V_200%for prostate; D_0.1ccfor urethra; and D_0.1ccfor rectum. While the dosimetric constraints were met for all plans, significant correlations against prostate volume were observed (p<0.05) in the following DVH parameters were exposed: prostate V_150%; D_1cc for urethra; D_10%, D_2ccfor bladder; and D_1cc, D_2cc, D_10%for rectum. Analysis of PRO measures gathered through the questionnaires to date, does not reveal any significant differences in toxicity between the two groups.

Conclusion

HDR BT plans created for prostate glands below and above 55cc met all dosimetric objectives and constraints. Significant correlations of certain DVH parameters against prostate volume do not seem to correlate with any clinically measurable toxicity differences between the two cohorts.