S18
Brachytherapy - Gastro-intestinal, paediatric brachytherapy, miscellaneous
ESTRO 2026
Conclusion: IBT boost after EBRT achieves excellent long-term control and sphincter preservation with acceptable tolerance in selected T1–T2 ACC. In this setting, HDR and PDR showed equivalent efficacy, confirming HDR as a safe and effective alternative in modern practice. Keywords: brachytherapy, anal canal carcinoma, HDR References: Annede P et al. ctRO 2023;39.Cordoba A et al. Brachytherapy 2017;16(1):230–5. Digital Poster 1062 Pulmonary changes after single dose interstitial brachytherapy for lung tumours Jafar Al Mansoor 1 , Ali Rashid 1 , Hathal Haddad 2 , Claudia Klein 1 , Horst Hermani 1 , Andreas Schäfer 3 , Peter Bischoff 3 , Attila Kovács 3 , Michael Pinkawa 1 1 Radiation Oncology, WEGE Klinik, Bonn, Germany. 2 Radiation Oncology, University of Tübingen, Tübingen, Germany. 3 Diagnostic and Interventional Radiology, WEGE Klinik, Bonn, Germany Purpose/Objective: The long-term reaction of lung tissue to extreme single doses occuring after brachytherapy has not been analyzed in the past. The knowledge of these changes over time are important to interpret comuted tomography (CT) images receiving high dose radiotherapy treatments. Material/Methods: Overall, 46 lung tumours were treated in a group of 32 patients has received with a single dose HDR (high dose rate) brachytherapy with a median prescription dose of 20Gy. Initial treatment planning CTs (n=46) and follow up CT images (n=154) that were performed up to 62 months after brachytherapy were evaluated retrospectively with consideration of the lesion location and time after brachytherapy (example in fig. 1).
Proffered Paper 444
Anal canal carcinoma: which patients still benefit from an interstitial brachytherapy boost — and is HDR the new standard? GREGOIRE LAURENT DELANGHE, PAUL ARCHER, ALEXANDRE TAILLEZ, XAVIER MIRABEL, ERIC LARTIGAU, ABEL CORDOBA University department of radiation oncology, Oscar Lambret Comprehensive Cancer Center, Lille, France Purpose/Objective: We conducted this retrospective study to evaluate long-term oncologic outcomes after interstitial brachytherapy (IBT) boost for anal canal carcinoma (ACC), and to compare pulse-dose-rate (PDR) and high- dose-rate (HDR) techniques in a homogeneous cohort treated with modern chemoradiation. Material/Methods: Between 2013 and 2024, 93 consecutive patients with histologically confirmed ACC were treated with pelvic external beam radiotherapy (EBRT) followed by an IBT boost. EBRT was delivered with IMRT or 3D-CRT.IBT boost was performed for tumors involving <50% of the anal circumference and clinically accessible. HDR or PDR technique was selected according to the treatment period (from 01/2013 to 05/2021: PDR; from 05/2020 to 12/2024: HDR). Survival outcomes— recurrence-free survival (RFS), colostomy-free survival (CFS), and local control (LC), OS and DFS—were estimated using Kaplan–Meier and Kalbfleisch– Prentice methods, with comparisons between HDR and PDR performed using log-rank and Gray’s tests. Results: After a median follow-up of 52 months (IQR 34–81), 90% of patients presented early-stage disease (T1–2) with 14% of nodal involvement. The median EBRT dose was 45 Gy in 25 fractions with 3% of 3D-CRT, and 48% of patients received concurrent chemotherapy. The median brachytherapy boost dose was 12 Gy (range 10–20 Gy), corresponding to an EQD2 ₁₀ of 13.3 Gy overall (HDR 14.0 Gy [11.8–16.3], PDR 12.0 Gy [9.3– 17.8]). Fifty-five percent received 12 Gy, 8% <12 Gy, and 38% >12 Gy, with ≥ 15 Gy almost exclusively in PDR. Median CTV was 27 cc (IQR 21–33). At five years, OS was 86.9% (95% CI 76.8–92.8) and DFS 79.4% (68.8– 86.8). The LC rate reached 94.3% (89.6–98.9), and both RFS and CFS were 90.8% (82.3–95.3). Seventeen relapses occurred (eight local, six metastatic), yielding a five-year cumulative incidence of local recurrence of 5.7%. A definitive colostomy was required in eight patients (8.6%) (4p due to relapse and 4p due to late toxicity). Grade ≥ 3 late toxicity was observed in 9.7% of the cohort. No significant difference was found between HDR and PDR for DFS (p = 0.65), CFS (p = 0.17), or LC (Gray’s p = 0.88).
Results: In the treatment planning CT after the intervention, a pneumothorax was observed in 15 (33%) of cases. An intervention (drainage) was required in 7 (15%) of
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