GSOR24 Presentation Time: 12:25 PM

Purpose

To assess whether bladder neck (BN) dose has an impact on urinary toxicity in women diagnosed with endometrial cancer (EC) treated with high-dose-rate vaginal cuff brachytherapy (VBT).

Materials and Methods

98 patients diagnosed with FIGO Stage I EC treated with exclusive VBT after total hysterectomy and bilateral salpingo-oophorectomy ± lymph node dissection between 2016 and 2020 were retrospectively analyzed. Twenty-one Gy in 3 fractions were delivered to the upper 1/3 of the vagina (4 cm) at 5 mm depth. The BN was defined on CT as a 5-mm expansion around the urethra immediately inferior to the Foley balloon. Urinary toxicity was evaluated using the Common Terminology Criteria for Adverse Events (CTACE) version 4.0, and classified into acute (AUT) and chronic (CUT) according to whether they appeared before or after 6 months of VBT. Dysuria, urinary incontinence, urinary urgency, nocturia, bladder tenesmus, hematuria and BN dosimetric parameters per fraction were collected, including maximum dose (Dmax) D2cc, D1cc and D0.5cc. Descriptive analysis has been carried out and parametric tests such as chi-square have been used.

Results

The BN mean volume was 2.34 cc (SD +/- 0.17). With a median follow-up 39 months, 33 patients (33.3%) presented AUT and 36 (36.7%) CUT. Grade II AUT was observed in two patients (2%) and grade III in another two (2%). Grade II CUT was observed in six patients (6%) and grade III in three (3%). The most common symptom was incontinence. Twelve (12%) and 27 (27%) patients presented some grade of acute and chronic incontinence, respectively. Dmax > 4.6 Gy and D2cc, D1cc and D0.5cc > 3 Gy was significantly associated with CUT (p <0.04). Regarding symptoms, Dmax > 4.6 Gy, D1cc > 3 Gy, D2cc and D0.5cc > 2.2 Gy were related with chronic urgency and incontinence (p < 0.02 and 0.04, respectively).

Conclusions

Our results suggest that dose to the bladder neck is related with chronic urinary toxicity, specially with urgency and incontinence, in EC patients treated with exclusive VBT. Larger sample size is needed to confirm the predictive value of this parameter.