Long-term results of stereotactic body radiotherapy boost in patients with cervical cancer considered unsuitable for intracavitary brachytherapy

Abstract

Abstract Purpose Although stereotactic body radiotherapy (SBRT) boost represents a promising treatment option for patients with locally advanced cervical cancer who were considered unsuitable for brachytherapy, its long-term efficacy and safety remain unclear. This study assessed long-term oncologic outcomes and late toxicities in a patient cohort from a previous phase I/II trial. Materials and methods This secondary analysis included 21 patients enrolled in an open-label, multicenter, single-arm, prospective phase I/II trial between January 2016 and October 2020. Patients with cervical cancer considered unsuitable for intracavitary brachytherapy received whole-pelvic radiotherapy (45 Gy in 25 fractions), followed by an SBRT boost to the primary tumor (21 Gy delivered in three consecutive daily fractions). The endpoints of this analysis included long-term oncological outcomes and late radiotherapy-related toxicities. Results The cohort comprised 21 patients, of whom 52% were aged ≥ 75 years, 81% had clinical stage III disease, and 43% had a maximum primary tumor size ≥ 70 mm. The median follow-up was 61.1 months (range, 10.4–111.0) for all patients and 71.9 months (range, 60.0–111.0) for surviving patients. The 5-year loco-regional control, progression-free survival, and overall survival rates were 84%, 62%, and 62%, respectively. Grade 3 late toxicity occurred in one patient (urinary tract obstruction), and no grade 4–5 toxicities were observed. Six patients experienced grade 2 late toxicities (proctitis, n = 3; fractures, n = 3). Conclusion This secondary analysis demonstrated encouraging long-term oncologic outcomes and an acceptable long-term safety profile following SBRT boost. These findings suggest that SBRT may represent a feasible treatment approach in carefully selected patients with locally advanced cervical cancer who are unable or unwilling to undergo brachytherapy.

The authors' abstract, as published at the source. Japanese Journal of Radiology, 2026 · DOI ↗