Implementation of image-guided brachytherapy as part of non-surgical treatment in inoperable endometrial cancer patients

Objective: This study assessed outcomes of inoperable endometrial cancer (IEC) patients treated with definitive external beam radiation therapy (EBRT) followed by a 3D image-guided brachytherapy boost. Methods: All consecutive patients treated with EBRT followed by 3D image-guided brachytherapy for IEC were retrospectively included. EBRT delivered a dose of 45Gy. Then, patients had an uterovaginal brachytherapy guided by 3D imaging. Clinical target volume (CTV_BT) included the whole uterus and the initial disease extent. Gross tumour volume (GTV_res) included the residual disease at time of brachytherapy. Results: Twenty-seven patients were identified. Causes of inoperability were comorbidities (37%) or tumour loco regional extent (63%). Including EBRT and brachytherapy, the median D₉₀ (minimal dose delivered to 90% of the volume) was 60.7 Gy_EQD2 (IQR = 56.4–64.2) for the CTV_BT, and was 73.6 Gy_EQD2 (IQR = 64.1–83.7) for the GTV_res. The median overall treatment time was 50 days (IQR = 46–54). The mean follow-up was 36.5 months (SD = 30.2). The cumulative incidence of local, pelvic and distant failures was 19% (n = 5), 7% (n = 2) and 26% (n = 7), respectively. Five-year overall survival was 63% (95% CI = 43–91). Late urinary and gastro intestinal toxicities ≥ grade 2 were reported in four (15%) and two patients (7%) respectively. No vaginal toxicity ≥ grade 2 was reported. Conclusions: EBRT followed by intracavitary brachytherapy seems to be an effective option for IEC. The implementation of 3D concepts at time of brachytherapy may contribute to high local control probability and low toxicity profile. Large scale retrospective or prospective data are needed to confirm these early data.