MRI-Guided SBRT Boost for Patients With Locally Advanced Cervical Cancer Who Are Unsuitable for Standard of Care...

In recent years, cervical cancer incidence has been on the decline in Australia, likely due to the HPV vaccination and an improved screening programme. However, an estimated 900 new cases will be diagnosed in 2025. The standard of care for locally advanced cervical cancer (LACC) is chemoradiotherapy, comprising external beam radiation therapy with concurrent cisplatin followed by image guided brachytherapy (IGBT), which is essential for optimal local control. Some patients will be ineligible for IGBT due to comorbidities, anaesthetic risk or technical challenges, with alternative EBRT boost techniques demonstrating higher toxicity and poorer patient outcomes. MR-guided stereotactic body radiotherapy (MRg-SBRT) offers improved soft tissue visualisation and daily adaptive planning, enabling accurate target coverage and reduced dose to organs at risk. MRg-SBRT is an investigational non-invasive boost option with emerging evidence supporting feasibility METHODS: We describe our early experience treating four patients with cervical cancer who were ineligible for IGBT following pelvic EBRT ± chemotherapy. All patients completed treatment with adaptive MRg-SBRT.

Median high-risk clinical target volume (HR-CTV) D98% was 78.7 Gy EQD2₁₀, demonstrating adequate target coverage. Early imaging showed one complete response, one local progression and one combined local and metastatic progression. Acute toxicities were predominantly Grade 1, with one case of Grade 3 pelvic pain and no Grade 4 events.

MRg-SBRT boost was feasible and well tolerated, achieving reasonable dose escalation with acceptable toxicity, representing a potential alternative for patients' ineligible for brachytherapy.

MARGARITA Protocol, NCT05937958.