ESTRO 2024 - Abstract Book

S257

Brachytherapy - Gynaecology

ESTRO 2024

Data from a Danish centre servicing all patients from the Central and North Regions of Denmark and implementing the EMBRACE-II protocol in 2015 was analysed and included all patients treated 2015-2019 with squamous cell (SQ), adeno-squamous (AdSq) or adenocarcinoma (AC) histology. For EBRT 45 Gy/25 fractions was prescribed to the pelvis. An extended para-aortic target was used if >2 pathological pelvic nodes were observed or if nodes were present in the common iliac or para-aortic region. Pathological nodes were treated with a simultaneous integrated boost to 55-57.5 Gy. EBRT was delivered with VMAT or IMRT. Weekly concomitant cisplatin 40 mg/m 2 was given whenever possible. Toxicity was evaluated weekly during treatment. Pulsed dose rate MRI based IGABT was performed using 2 implants and 2 fractions of 20 pulses one week apart in the 5-7th treatment week. Apart from vendor intracavitary tandem and ring applicators, different in-house 3D printed platforms for combined intracavitary/interstitial (IC/IS) implants were used. All patients were followed with MRI, PET-CT and gynaecological examination in general anaesthesia at 3 months after treatment. MRI was repeated at 12 months. Prospective follow-up was continued for 5-years. Survival status was obtained from the Danish Central Personal Register in January 2023.

Results:

In total 209/215 (97%) were treated according to EMBRACE-II. Ninety-six (46%) were included and 113 patients (54%) were not included in EMBRACE (Table 1).

Not included patients were on average 8-years older and more than twice as many had reduced performance status and presence of comorbidity. Local tumour stage was also significantly higher. However, percentage of patients in FIGO 2018 stage III-IV were not significantly different between the 2 groups. Treatment characteristics differed with a reduction from 90% to 49% of patients commencing concomitant chemotherapy and 60% and 30% being able to complete 5 course for the included and non-included groups, respectively. The use of para-aortic radiotherapy increased by 10% and the use of IC/IS BT was 12% more frequent for the not-included group. A D 90 of CTV HR >90 Gy EQD2 was achieved in 96% and 88% and for OAR all hard constraints were fulfilled simultaneously in 98% and 95% for included and non-included patients, respectively. The relationship between dose-volume parameters and local tumour extension using the T-score at brachytherapy is demonstrated in Figure 1.