Clinical Outcomes and Prognostic Factors Following Routine CT-Based Image-Guided Adaptive Brachytherapy for Cervical...

Background/Objectives: Magnetic resonance imaging (MRI)-based image-guided adaptive brachytherapy (IGABT) is the preferred standard for cervical cancer, but access remains limited in many settings. Computed tomography (CT)-based IGABT provides a practical alternative. We evaluated clinical outcomes and prognostic factors following its routine implementation. Methods: This retrospective cohort study included patients with International Federation of Gynecology and Obstetrics (FIGO) 2018 stage I-IVA cervical carcinoma treated with definitive radiotherapy incorporating CT-based IGABT from January 2019 to December 2021. Patients received pelvic external beam radiotherapy (45-50.4 Gy in 23-28 fractions), with or without concurrent platinum-based chemotherapy, followed by four high-dose-rate brachytherapy fractions. Local control and overall survival were estimated using Kaplan-Meier analysis, and prognostic factors were evaluated using Cox regression. Results: Among 237 patients, 56.9% had FIGO stage III-IV disease, and hybrid intracavitary/interstitial brachytherapy was used in 30.2% of fractions. The mean high-risk clinical target volume D90 (HR-CTV D90) was 85.4 ± 2.7 Gy EQD₂. Median follow-up was 59.9 months for local control and 71.1 months for overall survival. The 5-year local control and overall survival rates were 84.4% (95% CI, 79.1-88.5%) and 62.9% (95% CI, 56.3-68.8%), respectively. Squamous histology was independently associated with improved local control and overall survival. HR-CTV D90 ≥ 85 Gy EQD₂ was associated with improved local control, whereas ≥4 chemotherapy cycles and overall treatment time ≤ 56 days were associated with improved overall survival. Conclusions: Routine CT-based IGABT achieved clinically meaningful outcomes despite the high proportion of advanced-stage disease. Achieving HR-CTV D90 ≥ 85 Gy EQD₂, delivering ≥4 chemotherapy cycles, and completing treatment within 56 days were associated with improved outcomes.