Abstract
Can image-guided external beam radiotherapy boost be an alternative when intracavitary brachytherapy is unavailable for locally advanced cervical cancer? A dosimetric analysis and literature review
Department of Radiation Oncology, Shijiazhuang People’s Hospital, Hebei Province 050011, China
J Contemp Brachytherapy 2026; 18, 2: 171–178
Purpose
Intracavitary brachytherapy (ICBT) is a critical component of definitive radiotherapy for locally advanced cervical cancer (LACC). However, ICBT may be unavailable due to resource limitations, anatomical constraints, or patient refusal. This study aimed to evaluate the feasibility of an image-guided external beam radiotherapy (EBRT) boost using modern techniques, such as intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) from a dosimetric perspective, and to compare the results with published data from ICBT and stereotactic body radiotherapy (SBRT) studies.
Material and methods
Ten patients with LACC (FIGO stage IIB-IVA) were prospectively enrolled and treated using whole pelvic IMRT/VMAT (45 Gy in 25 fractions) with a simultaneous integrated boost (SIB) or sequential boost to high-risk clinical target volume (HR-CTV). Prescribed dose to HR-CTV was 70 Gy (EQD2: 79.8 Gy, α/β = 10). Daily image-guided radiotherapy (IGRT) was performed. Dose-volume histogram (DVH) parameters for targets and organs at risk (OARs) were analyzed and compared with historical and recent literature data on ICBT and EBRT/SBRT boosts.
Results
The mean D95% and D90% for HR-CTV were 81.6 ±0.2 Gy and 84.9 ±0.4 Gy (EQD2), respectively. The mean D98% (approximated by Dmin) was 74.5 ±3.1 Gy (EQD2), and the mean volume receiving < 95% of the prescribed boost dose (V < 95%) was 5.0 ±1.5%. The mean D98% for the pelvic PTV was 50.5 ±0.7 Gy. The cumulative EQD2 (α/β = 3) D2cc for the rectum, sigmoid, and bladder were 67.9 ±2.3 Gy, 68.8 ±3.1 Gy, and 74.4 ±2.7 Gy, respectively, which were within tolerance limits recommended by the GEC-ESTRO and ABS guidelines. These OAR doses were comparable or lower than those reported in recent SBRT boost series.
Conclusions
From a dosimetric perspective, an image-guided EBRT boost using IMRT/VMAT with daily IGRT is feasible for LACC patients when ICBT is not an option. It provides a high, uniform dose to the target while respecting OAR constraints. While ICBT remains the gold standard, modern EBRT techniques offer a promising alternative in resource-constrained settings. The dosimetric findings from this study support the design of a prospective clinical trial (in development, planned registration) to evaluate clinical outcomes, including toxicity and local control.
Keywords
cervical cancer, external beam radiotherapy, IMRT, VMAT, brachytherapy, dosimetry
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