Precision brachytherapy for bulky cervical tumors: Clinical implementation of a 3D-printed template and curved needle system

Purpose
Locally advanced cervical cancer (LACC) in bulky tumors and parametrial invasion poses substantial challenges for effective brachytherapy, often resulting in sub-optimal target coverage and increased risk for adjacent organs. This study evaluated the clinical feasibility, dosimetric performance, and early outcomes of a novel high-dose-rate brachytherapy strategy using patient-specific 3D-printed templates and curved flexible needles in LACC.

Material and methods
We retrospectively analyzed 20 patients with stage IIIB-IVB cervical cancer treated between July 2023 and August 2024. All patients received pelvic intensity-modulated radiotherapy and concurrent cisplatin-based chemotherapy, followed by brachytherapy via a dual-needle technique. Personalized 3D-printed templates were designed on the basis of pre-treatment magnetic resonance imaging to optimize needle trajectories and accommodate anatomical variations. Dosimetric parameters, target coverage, organ at risk doses, and clinical outcomes were assessed.

Results
The mean high-risk clinical target volume (HR-CTV) was V100 value of 86.5% (standard deviation of 7.6%), with a mean D90 equivalent dose in 2 Gy fractions (EQD2) of 89.1 Gy for combined external beam and brachytherapy treatment. The doses to organs at risk remained below the recommended thresholds, with a mean bladder and rectum D2cc EQD2 of 79.4 Gy and 72.7 Gy, respectively. At a median follow-up of 12.8 months, the one-year overall survival and progression-free survival rates were 85% and 75%, respectively. No grade 3 or higher acute toxicities were observed.

Conclusions
The integration of 3D-printed templates and curved flexible needles enables precise and individualized brachytherapy for bulky and parametrial invasive cervical cancer, achieving high target conformity and effective organ sparing. This approach demonstrates promising early efficacy and safety, supporting its potent advanced solution for complex LACC cases.