ESTRO 2025 - Abstract Book

S236

Brachytherapy - Gynaecology

ESTRO 2025

Material/Methods: A new dose prescription protocol was developed for favorable-risk cervical cancer (node-negative, FIGO-stages I&II, squamous histology, tumor width @diagnosis <5cm, no mid/upper-uterine or distal-parametrium involvement) in the RAPID study. This protocol involves an EBRT dose de-escalation of 40Gy/20fx and BT dose adapted to GTV res volume at BT. To better control the BT peripheral target dose, CTV HR D98% is prioritized as the primary dose planning aim, replacing the previous focus on the CTV HR D90%. Planning aims include ideal, lower and upper bound and allow for an absolute CTV HR D98% aim while having flexibility to modulate dose to meet all other targets’ constraints (Figure1). Constraints were based on prior simulations in 312 favorable-risk patients from EMBRACE-II study (1). Feasibility and refinement of the dose prescription protocol was performed through a retrospective replanning of 10 favorable-risk patients treated with standard-of-care and intracavitary/interstitial Venezia applicator.