3508 - Hypofractionated Pelvic Irradiation Followed by Image-Guided Brachytherapy in Women with Primary Gynecological Carcinoma or Oligometastatic Disease to Gynecological Tract: A New Paradigm of Care

D. F. Hamade¹, H. Wang², and P. N. Barry³; ¹UPMC-Shadyside Hospital Department of Radiation Oncology, Pittsburgh, PA, ²Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA, ³University of Pittsburgh Medical Center, Pittsburgh, PA

Purpose/Objective(s): Evaluate the efficacy and tolerability of modestly hypofractionated pelvic radiotherapy followed by image-guided brachytherapy in women with primary gynecological carcinoma or oligometastatic disease to the gynecological tract. Materials/

Methods: A total of thirteen patients treated with hypofractionated pelvic radiotherapy and MRI-guided brachytherapy between September 2019 and March 2023 at UPMC Hillman Center. They received a dose ranging from 30 to 42 Gy in 10 to 15 fractions of IMRT/IGRT followed by 21 to 36 Gy in 3 to 6 fractions of HDR brachytherapy. There were ten cases of endometrial cancer, two cases of vaginal cancer, and a single oligometastatic case to the cervix. Brachytherapy was delivered by means of a tandem-based applicator (n = 7), Syed (n = 1), Y-applicator (n = 1), or multichannel vaginal cylinder (n = 4). Most patients (n = 8) were treated with definitive radiotherapy, two patients received adjuvant radiotherapy, one patient received salvage radiotherapy and two patients received salvage chemotherapy and radiotherapy with either 6 cycles of Carboplatin plus Paclitaxel or concurrent capecitabine. No patients received radiosensitizing chemotherapy.
Results: The mean/median EQD2 to the GTV were 88.91/89.00 Gy and that to the HR-CTV 71.48/70.08 Gy. Similarly, the dose to the organs at risk was limited to a mean/median D2cc of 58.27/57.16 Gy to the bladder, 52.99/52.90 Gy to the rectum, 54.76/55.6 Gy to the sigmoid, 55.39/53.03 Gy to the small bowel, and a mean/median D50% of 17.49/19.12 Gy to the pelvic bones. Radiotherapy was well tolerated and there were no reported grade 3 or higher toxicities. At 2 years, a total of 5 patients recurred, two locally, two distally, and one locally and distally, for a 2-year locoregional recurrence (LRR) rate of 30% and distant metastasis (DM) rate of 31%. At the time of analysis, four patients had died, two of whom from disease recurrence, making the 2-year progression free survival (PFS) and overall survival (OS) rates 45% and 79%, respectively. During treatment, three patients experienced grade 1 acute gastrointestinal toxicity, and one patient had grade 2 vaginal stenosis secondary to not being compliant with the vaginal dilator.
Conclusion: The results of this retrospective single institution analysis conducted at UPMC suggests that hypofractionated IMRT followed by image-guided brachytherapy for the management of primary gynecological cancers or oligometastatic disease to the gynecological tract is well tolerated at short-term follow-up and resulted in acceptable disease control and survival, therefore warranting the initiation of a prospective phase 1/2 nonrandomized controlled trial to adequately evaluate this treatment paradigm.