ESTRO 2024 - Abstract Book

S982

Clinical - Gynaecology

ESTRO 2024

treatment details, were retrieved retrospectively from corresponding medical records. Patients were followed up clinically with pelvic examination every 3 to 6 months for up to 3 to 5 years (data lock 30th June, 2023). MRI was performed routinely at 3 months post RT/CCRT and repeated at 2-3 monthly intervals if there was incomplete response or if recurrence was suspected.

Results:

In total, 222 patients were identified. Median age was 50 years (range 23 - 89) and median follow up was 41 months (range 3-70). Pathology subtype consisted of squamous cell carcinoma (80.6%), adenocarcinoma (14.4%), and adenosquamous / other (5%). FIGO 2009 and 2018 stage distribution was as follows: IB (13.5%, 10.8%), II (70.3%, 44.1%), III (9.0%, 37.9%), IVA (7.2%, 7.2%). MRI at diagnosis was performed in 96.7% and PET-CT was available in 97.4%. Median primary tumour size was 45mm (range 10-110). Concurrent cisplatin was administered to 88.3% (median 5 cycles, range 1-6) and 25.2% received neoadjuvant chemotherapy (median 3 cycles, range 1-6). EBRT dose delivered to the pelvis was 5000cGy/25# in 17.6 %, 4500cGy/25# in 80.1%, and 4300cGy/20# in 2.3%. Median brachytherapy dose was 2400cGy/4#. Analysis of outcomes was performed only in those patients who completed EBRT and had pre- and post- treatment MRI available, representing 90% (200/222) of the cohort. At 3 months, imaging response assessment demonstrated complete response (CR) in 55.5% (111/200), partial response (PR) in 41.5% (83/200), and progressive disease (or indeterminate) in 3% (6/200). By 6 months and 9 months, the CR rate increased to 77.5% (155/200) and 82.5% (165/200). The proportion of patients who were disease free at last follow up based on CR at 3 months, 6 months, and 9 months were 86.5% (96/111), 87.7% (136/155), and 87.9% (145/165), respectively. There were only 4 cervical recurrences in patients who achieved CR on MRI by 3-9 months, resulting in local control rate of 97.6% (161/165) accordingly.

Conclusion:

CR rate on MRI at 3 months post CCRT is lower in a real-world population compared to the remarkable results reported in EMBRACE-1 and is likely related to IGBT technique; we plan to repeat the study following implementation of CTV HR IGBT. However, we have also shown that resolution of disease by 6 to 9 months has equivalent outcomes. Repeated MRI to detect local recurrence following CR is unlikely to be advantageous as the majority of relapses occur out with the cervix. Well-designed clinical trials with defined imaging regimens are required in order to determine whether earlier detection of recurrence has a survival benefit.

Keywords: MRI, cervical cancer, chemoradiotherapy

References:

1. Schmid MP et al. Risk factors for local failure following chemoradiation and magnetic-resonance image-guided brachytherapy in locally advanced cervical cancer: Results from the EMBRACE-1 study. JCO 2023; DOI https://doi.org/10.1200/JCO.22.01096

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