ESTRO 2024 - Abstract Book

S989

Clinical - Gynaecology

ESTRO 2024

565

Poster Discussion

AI-enhanced Adaptive Intensity Modulated radiotherapy for Cervical cancer (AIM-C): Early experience

Ajcharee Nuengsigkapian 1 , Petch Alisanant 2 , Kanokphorn Thonglert 2 , Chonlakiet Khorprasert 1 , Julaluck Chanayota 2 , Napapat Amornwichet 1 1 Chulalongkorn university, Division of radiation oncology, Department of radiology, Faculty of medicine, Bangkok, Thailand. 2 King Chulalongkorn memorial Hospital, Division of radiation oncology, Department of radiology, Bangkok, Thailand

Purpose/Objective:

Intensity-modulated radiotherapy (IMRT) has been shown to reduce GI toxicity. (1) Nevertheless, it is essential to account for an internal target volume (ITV) due to inter- and intrafraction uterine movement. Daily adaptive radiotherapy (ART) can further reduce the ITV, leading to a decrease in the volume of the planning target volume (PTV). Consequently, we anticipate that decreasing the size of the PTV will result in a subsequent reduction in gastrointestinal (GI) toxicity by minimising radiation exposure to the adjacent bowel. Adaptive radiotherapy enables the adjustment of radiation dosage distribution based on the patient's anatomical characteristics during each treatment session through the use of real-time imaging and adapt the radiation delivery plan. Our objective is to find the incidence of gastrointestinal adverse events by implementing daily online ART

Material/Methods:

This single-centre phase II trial was done to assess the efficacy of ART in patients diagnosed with FIGO stages IB3 IIIC1 cervical cancer. All patients received cisplatin-based CRT and external beam radiotherapy (EBRT) at a dose of 45 Gy over 25 fractions using the linear accelerator ETHOS (Varian Medical Systems).Involved pelvic lymph node was simultaneous integrated boost to 55Gy. The process involves reviewing and editing changes to the shapes of the CTV (uterus, cervix, proximal vagina, parametria, and pelvic lymph nodes) and OARs (bowel, bladder, and rectum) on daily CBCT. PTV is auto-generated by adding a 5-mm uniform margin to the adapted CTV to compensate intrafraction motion. Followed by rechecking the auto-generated adaptive treatment plan based on the set planning aim and constraints. MRI-based brachytherapy was subsequently performed at the end of treatment. The primary outcome is the incidence of acute gastrointestinal (GI) adverse events reported by physicians, utilising the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 from the initiation of radiation treatment until three months after the end of radiation. The secondary outcomes are the incidence of genitourinary, hematologic, and general systems, as well as the radiation dosage, the duration of treatment time per session, and patient-reported quality of life using the EORTC questionnaires.

Results:

Twelve patients (1 with stage IB3, 8 with stage IIB, and 3 with stage IIIC1) received 284 ART treatments between October 1, 2022, and October 20, 2023. The adapted plan was selected 99.3% of the time. The median follow-up duration was 3.4 months. The incidence of grade 1 GI adverse events was 41.67%, with no occurrences of grade 2 and 8.33% experiencing grade 3. All patients experienced grade 1 GU adverse events, primarily dysuria and urinary frequency. 25% of patients experienced grade 1-2 neutropenia with no cases of grade 3. Dosimetrically,