ESTRO 2025 - Abstract Book

S216

Brachytherapy - Gynaecology

ESTRO 2025

Conclusion: The adaptive CT-guided IS-ICBT application is an efficient method resulting in use of fewer needle and increased dwell intensity per needle. Image guided needle placement resulted in achieving higher dose to HRCTV in patients with high-volume disease. It also enable to decrease toxicity to OARs in both low and high volume disease There were no significant complications during the procedure.

Keywords: brachytherapy, cervical cancer, interstitial

References: 1.

Tambas, M., Gill, A., Ma, Y., Westerveld, H., Paulsen Hellebust, T., Rusch, T., & Tanderup, K. (2021). Computed tomography–guided optimization of needle insertion for combined intracavitary/interstitial brachytherapy with Utrecht applicator in locally advanced cervical cancer. Practical Radiation Oncology, 11(4), 272–281. 2. Fokdal, L., Sturdza, A., Mazeron, R., Haie-Meder, C., Hoskin, P., Bruheim, K., ... & Kirisits, C. (2016). Image-guided adaptive brachytherapy with combined intracavitary and interstitial technique improves the therapeutic ratio in locally advanced cervical cancer: Analysis from the retroEMBRACE study. Radiotherapy and Oncology, 120(3), 434– 440.

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Digital Poster Response Adapted Precise and Individualized Dose in favorable risk cervical cancer (RAPID - Cervix): A preinitiation feasibility study. Prachi Mittal 1 , Monica Serban 2,3 , Anjana AK 4 , Jeevanshu Jain 4 , Kamalnath J 4 , Sofia Spampinato 5 , Ankita Gupta 4 , Inger Karine Kolkman-Deurloo 5 , Henrike Westerveld 5 , Kari Tanderup 6,7 , Remi A Nout 5 , Supriya Chopra 4 1 Department of Radiation Oncology, Tata Memorial Hospital, Tata Memorial Centre, Homi Bhabha National University, Mumbai, India. 2 Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Canada. 3 Department of Radiation Oncology, University of Toronto, Toronto, Canada. 4 Department of Radiation Oncology, Advanced Centre for Treatment Research and Education in Cancer, Tata Memorial Centre, Homi Bhabha National Institute, Navi Mumbai, India. 5 Department of Radiotherapy, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Rotterdam, Netherlands. 6 Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark. 7 Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark Purpose/Objective: RAPID study is designed to adapt dose prescription based on residual Gross Tumour Volume (GTV-T res ) at brachytherapy (BT) in patients with favourable-risk cervical cancer to reduce treatment-related toxicity. While feasibility based on dose rescaling simulations has been previously reported 1 , feasibility across various applicators, ovoids, ring, intracavitary (IC) and intracavitary-interstitial (IC-IS), GTV-T res volume and its location in cervix has yet to be evaluated. This pre-initiation study was undertaken to assess the feasibility of meeting RAPID study dose constraints across various scenarios. Material/Methods: Previously treated patients with radio-chemotherapy including MRI-based BT who fulfilled the RAPID-Cervix study eligibility criteria (squamous histology, FIGO 2018 stage IB1–IIB with negative nodes, proximal parametrial invasion and without necrosis or mid- or upper-uterine involvement with maximum tumour dimension <5cm) were identified. Patients were selected to represent different scenarios for GTV response and location in cervix and organs at risk (OAR) proximity while using variety of IC/IC-IS applicators. EBRT dose was 40Gy/20 fractions. Adaptive dose constraints for BT were based on GTV-T res ≤5 or GTV-T res >5cm 3 and were summarized as cumulative EQD2 in Table 1. Proportion of patients achieving hard and soft dose constraints was assessed.