3D Image-Guided Brachytherapy as Only Treatment for Stage-I Inoperable Endometrial Cancer: Retrospective Analysis of the Gynecological Cancer GEC-ESTRO Working Group

Abstract

Analyze the outcomes of stage-I inoperable endometrial cancer (EC) patients treated with 3D-image-guided brachytherapy without external beam irradiation hypothesizing that this treatment provides very good results.Medical records of EC patients treated in 7 European centers from 2004-2018 with exclusive IGBT were examined, including: an aesthetic procedure, applicator type, BT-planning imaging, clinical target volume (CTV), BT schedule, overall daily dose equivalent to 2Gy fractions (EQD2(α/β = 4,5 or 3)) to the CTV(α/β = 4,5) and D2cm3(α/β = 3) for organs at risk. Complications were evaluated using CTCAEv4 scores. Survival probability at 2 and 5 years was estimated (cancer-specific survival [CSS], disease-free survival [DFS], local relapse-free survival [LRFS], loco-regional relapse-free survival [LRRFS] and distant metastasis-free survival [DMFS]).Survival analysis included descriptive analysis and the Kaplan-Meier method.A total of 62 patients staged IA (41) and IB (21) were included. Mean follow-up: 32.8 months (SD 33.7). Spinal anesthesia (38/62) followed by no anesthesia (16/62) were most common. Y-Shaped Rotte was the most common (in 74% of patients) and high-dose radiation (HDR) was used in 89%. Median D90 EQD2(α/β = 4.5) to the CTV was 58.9Gy (8.66-144Gy). Eight patients presented relapse: uterine in 4, nodal in 4 and distant in 4. At 2- and 5-years CSS was 93.3% and 80.5%, DFS 84.8% and 80.5%, LRFS was 93.1% and 88.7%, LRRFS was 91% and 91% and DMFS was 90.2% and 90.2% respectively; CSS in stages-IA and IB at 2 and 5 years was 96.6% and 88.7% vs. 77.5% and 64.6% respectively (P = 0.043). Late vaginal and bladder G3-complications rates were 2.1%, respectively.Inoperable EC patients can be safely treated by BT with CSS at 2 and 5 years of 93% and 80.5%, respectively, and better results for stage IA cases. Prospective studies on 3D-image-guided BT can help better analyses patient outcomes and draw dose/volume effect relationships for tumor control.