ESTRO 2024 - Abstract Book

S247

Brachytherapy - Gynaecology

ESTRO 2024

Vincent Dick, Johannes Knoth, Nicole Eder-Nesvacil, Christian Kirisits, Joachim Widder, Maximilian Schmid, Alina Sturdza

Medical University of Vienna, Radiation Oncology, Vienna, Austria

Purpose/Objective:

To evaluate local control (LC), locoregional control (LRC), distant control (DC) and overall survival (OS) for patients with vaginal recurrence of endometrial cancer receiving salvage radiotherapy with image-guided adaptive brachytherapy (IGABT) +/- external beam radiotherapy (EBRT).

Material/Methods:

We retrospectively evaluated all consecutive patients treated in curative intent with IGABT +/- EBRT for vaginal recurrence of endometrial carcinoma after initial surgical treatment with or without adjuvant radiotherapy treated at our department between 2001 and 2020. Patients with mainly superficial recurrences in the vaginal wall were treated with IGABT alone (group 1). Patients with more advanced tumors extending beyond the vaginal wall or with pelvic lymph node metastases received pelvic EBRT (45-50.4 Gy) + IGABT (group 2). IGABT was performed using MRI- or CT-guidance. The IGABT high-risk clinical target volume (CTV-HR) consisted of the macroscopic tumor and an individual margin in group 1 and the residual tumor plus surrounding suspicious tissue (e.g. grey zones in MRI) in group 2. Treatment of the whole vagina as low/intermediate-risk clinical target volume was left at physician’s discretion. Planning aim to the CTV-HR was 70-80 Gy (EQD210) for group 1 and 85 Gy (EQD210) for group 2. Actuarial LC, LRC, DC and OS were calculated using the Kaplan-Meier method; long-term G3-5 toxicity was recorded (CTCAE v5 criteria). We identified 46 patients, median age at recurrence was 69 years (range 48-85). Median time to vaginal recurrence following hysterectomy was 19.5 months (0-129). Nine patients received previously radiotherapy as part of the primary treatment at first diagnosis (brachytherapy (BT) for 5 patients, EBRT for 2 patients, EBRT + BT for 2 patients). Recurrent tumors were mostly located in the proximal third of the vagina (n=30), with the remaining tumors occuring in the middle (n=3) and distal (n=4) third of the vagina, periurethral (n=6) or multifocal (n=3). Infiltration of the paravaginal tissue was present in 16 patients. Six patients presented with positive regional lymph nodes at the time of recurrence and three presented with oligometastatic disease (lung n=2, non-regional lymph node n=1). Radiotherapy treatment for recurrence consisted of IGABT alone for 15 patients and of EBRT+IGABT for 31 patients. IGABT was performed as pulsed dose rate brachytherapy (PDR-BT) for 23 patients and as high dose rate brachytherapy (HDR-BT) for 22 patients. One patient received both PDR-BT and HDR-BT. Five patients had previous partial tumor resection (4 patients received IGABT alone, 1 patient EBRT+IGABT). Three patients received concurrent or sequential platinum-based chemotherapy. Median follow-up for survival was 61 months for the entire cohort and 85 months for surviving patients. OS for the entire cohort was 76.5 % at 5 years. Median follow-up for disease control was 41 months. LC, LRC and DC after 2 and 5 years for the entire cohort was 97.4 %/92.0 %, 95.2 %/83.7 % and 86.6 %/81.4 %, respectively. Histology of the recurrent tumor was endometrioid adenocarcinoma for 43 patients, serous carcinoma for one and not recorded for two patients. Results: