Clinical outcomes with triple tandem brachytherapy for medically inoperable endometrial cancer in a high-risk patient population

The purpose of this study is to evaluate clinical outcomes for medically inoperable endometrial cancer (MIEC) patients treated with triple tandem brachytherapy (TTB) ± external beam radiation therapy (EBRT).

This single institution retrospective review analyses MIEC patients treated definitively with TTB ± EBRT from 2014 to 2021. FIGO stage I-II with Grade 1-2 histology were considered low-risk endometrial cancer (LREC) and FIGO stage III-IVB and/or any Grade 3 endometrioid carcinoma, clear cell, or serous carcinoma were considered high-risk endometrial cancer (HREC). Planning parameters for target volume(s) and OARs (organs at risk) were per ABS guidelines. Overall survival (OS) and local failure-free survival (LFFS) were estimated by Kaplan-Meier analysis. Local control (LC), acute and late toxicities were evaluated clinically.

Of 26 patients, 92.3% (n = 24) received TTB + EBRT. The median age at diagnosis was 66.5 years (40.5-88.7 years). Median follow up was 41.1 months (1.7-109.9 months). Median prescribed doses to the uterus were 45 Gy (0-50.4 Gy) for EBRT and 22.25 Gy (18-49.1 Gy) for TTB. 53.8% (n = 14) had LREC and 46.2% (n = 12) had HREC. 88.5% had endometrioid histology. The median OS for the entire cohort was 43.5 months with no difference for the LREC and HREC (p = 0.563). LC was superior (p = 0.032) in LREC patients (100% 4-year LFFS) with all recurrences occurring in the HREC cohort (1-/4-year LFFS 90.9%/62.3%). Late toxicities > Grade 2 were: Grade 2 GU (n = 2) and Grade 2 GI (n = 1).

Definitive TTB ± EBRT for MIEC patients was associated with excellent LFFS and acceptable toxicity rates.