2898 - Development and Assessment of Interstitial Brachytherapy Using Individual Curved-Needle in Treatment of Recurrent Gynecological Tumors after External Beam Radiotherapy
Presenter(s)
Z. Zeng1, Y. Chen2, J. Yan3, K. Hu1, and F. Zhang3; 1Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China, 2Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China, Beijing, China, 3Department of Radiation Oncology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
Purpose/Objective(s): Treating recurrent gynecologic cancer remains a significant clinical challenge. The aim of this study was to evaluate the efficacy and safety of individualized curved-needle interstitial brachytherapy (ISBT) using three-dimensional (3D) printing for recurrent gynecologic tumors.
Materials/Methods: This study enrolled patients with pelvic recurrent gynecological tumors from March 2022 to April 2024. All eligible patients received external beam radiotherapy (EBRT) at doses of 40-60 Gy over 20-30 fractions, followed by individualized curved-needle ISBT using a 3D-printed applicator, with a prescribed dose of 12-30 Gy over 2-5 fractions. Concurrent systemic therapy was administered when necessary. Dosimetric parameters for the high-risk clinical target volume (including V100%, V200%, D100%, D98%, D90%, D50%) and organs at risk (including D5cc, D2cc, D0.1cc) were assessed. Clinical outcomes were analyzed, and treatment-related complications were graded.
Results: The final analysis included 45 fractions of ISBT. Central and non-central pelvic recurrences accounted for 46.2% and 53.8%, respectively, with 4 (30.8%) patients undergoing re-irradiation. Eight (61.5%) patients received concurrent systemic therapy. During brachytherapy, 2-6 curved needles (median 3) were inserted per fraction. The cumulative equivalent dose in 2-Gy fractions delivered to the gross tumor volume was 64.87 ± 7.16 Gy for patients with a history of radiation and 73.03 ± 9.95 Gy for patients without. The mean D2cc for the bladder, rectum, and sigmoid were 450.00 ± 118.17 cGy, 328.00 ± 108.47 cGy, and 268.00 ± 102.87 cGy per fraction for patients with a radiation history. All patients were alive at a median follow-up of 25 months (range 9-40 months). The objective response rate was 84.6% for the whole body and 92.3% for the local tumor. The 2-year local control, progression-free survival, and overall survival rates were 91.7%, 83.9%, and 100%, respectively. No Grade 4 or 5 toxicities were reported. Grade 3 acute toxicities were observed in 30.8% of patients, including 23.1% hematological and 7.7% urinary toxicity. Grade 3 late toxicity occurred in 7.7% of patients, while Grade 1-2 late toxicities were seen in 38.5%.
Conclusion: Individualized curved-needle ISBT with a 3D-printed applicator offers high-quality treatment and results in favorable outcomes with acceptable toxicity for recurrent gynecological tumors following EBRT.