자궁경부암의 근치목적 방사선치료 시 추가방사선치료 기법으로 근접치료를 대체하여 통상분할 외부 방사선치료 적용의 적격성 평가 = Eligibility analysis for external beam boost radiotherapy as a substitution of intracavitary radiotherapy for radical radiotherapy of cervical cancer

다국어 초록 (Multilingual Abstract)

Purpose
Intracavitary brachytherapy (ICR) remains the standard boost modality for cervical cancer, but it is not feasible for all patients due to anatomical, clinical, or facility limitations. This study aimed to evaluate the clinical outcomes and toxicity profile of external beam radiotherapy (EBRT) boost compared to ICR boost and to assess its feasibility as an alternative treatment option in patients with cervical cancer.

Materials & Methods
This retrospective study included 64 patients with cervical cancer who received curative-intent radiation therapy between January 2015 and December 2024. Patients were divided into two groups: EBRT boost (n=31) using primarily intensity-modulated radiotherapy (IMRT), and ICR boost (n=33) using high-dose-rate brachytherapy. Treatment response was assessed using MRI, and survival outcomes were analyzed using the Kaplan-Meier method. Toxicity was evaluated using RTOG criteria. Statistical analysis included univariate and multivariate analyses to identify prognostic factors.
Results
The median follow-up was 20.8 months for the EBRT group and 37.8 months for the ICR group. Complete response rates were comparable between groups (67.7% vs. 69.7%, p=0.866). Two-year progression-free survival rates were 61.5% and 69.4% (p=0.412), and locoregional recurrence-free survival rates were 70.9% and 72.9% (p=0.435) for EBRT and ICR groups, respectively. Mean total equivalent dose in 2 Gy fractions (EQD2) was lower in the EBRT group (64.5 vs. 79.6 Gy). Treatment duration was significantly shorter in the EBRT group (57 vs. 77 days). Late gastrointestinal toxicity differed significantly between groups, with grade ≥2 toxicity occurring in 0% of EBRT patients versus 51.5% of ICR patients (p<0.001). Grade 3-4 toxicity occurred only among ICR patients treated with EQD2 ≥81.1 Gy. On multivariate analysis, failure to achieve complete response and FIGO stage III-IV were significant predictors of unfavorable outcomes.

Conclusions
Comparable local control outcomes with reduced late GI toxicity were observed in the EBRT boost group. EBRT boost may be considered a practical alternative for patients in whom ICR boost cannot be performed.

목차 (Table of Contents)

• 1. Abstract 1
• 2. Introduction 3
• 3. Materials and Methods 6
• 4. Results 10
• 5. Discussion 14
• 6. Conclusion 20
• 7. References 21
• 8. Figures and Legends 27
• 9. Tables 33
• 10. Abstract (Korean) 40