ESTRO 2025 - Abstract Book

S246

Brachytherapy - Gynaecology

ESTRO 2025

To investigate the impact of uterine position on treatment planning parameters, oncologic outcomes, and toxicity profiles in cervical cancer patients treated with definitive chemoradiotherapy followed by high-dose rate intracavitary brachytherapy (ICBT). Material/Methods: We conducted a retrospective analysis of non-metastatic patients treated between 2012 and 2022. All patients received 45-50.4 Gy external beam radiotherapy followed by 28 Gy ICBT in 4 fractions. Uterine positions during ICBT were documented for every fraction. Patients with variations in uterine position between fractions were excluded. Results: A total of 278 patients were evaluated. After the exclusions, 222 patients with an anteverted and 29 with a retroverted uterus were included in the analyses (Table 1). During ICBT, a tandem and ovoids were used for all patients with a retroverted uterus while a tandem-ring applicator was employed for 51 (23%) patients with an anteverted uterus. The median follow-up was 44 months (range: 1-134 months). The 2- and 5-year overall survival rate was 82% and 71% for an anteverted uterus compared to 77% and 77% for a retroverted uterus, respectively (p=0.8). The 2- and 5-year disease-free survival rate was 72% and 66% for an anteverted vs. 76% and 69% for a retroverted uterus, respectively (p=0.83). Local recurrence developed in 21 (10%) and 3 (11%) patients with an anteverted and a retroverted uterus, respectively (p=0.89). Median total doses to the high-risk and intermediate-risk clinical target volume (CTV) were significantly higher for an anteverted uterus (91.3 vs. 89.8 Gy, p=0.001; and 67.4 vs. 65.9 Gy, p=0.044). However, patients with a retroverted uterus received a higher total median dose to the rectum (76.3 Gy vs. 79.7 Gy, p=0.001) and bowel (66.4 Gy vs. 73.7 Gy, p=0.023), yet lower to the sigmoid (63.4 Gy vs. 59.9 Gy, p=0.005). Late grade ≥3 gastrointestinal (GI) and genitourinary toxicity developed in 14 (6%) and 3 (1%) patients, respectively. The rate of total toxicity was similar in both groups except that late grade 1-2 GI toxicity was higher in patients with a retroverted uterus (4% vs. 17%, p=0.019).