3480 - The Comparison of Vaginal Cuff Brachytherapy and External Pelvic Radiotherapy in Stage IB Grade 3 Endometrial Cancer

The Comparison of Vaginal Cuff Brachytherapy and External Pelvic Radiotherapy in Stage IB Grade 3 Endometrial Cancer

Purpose/Objective(s): The aim of this study is to compare vaginal cuff brachytherapy (VBT) and external pelvic radiotherapy (EPRT) in terms of oncological outcomes and toxicity in patients with stage IB (FIGO 2018) grade 3 endometroid type endometrial cancer.

Materials/

Methods: The records of 85 patients from two cancer centers, who received VBT or EPRT between 1994-2021, were evaluated retrospectively. The patients who received only EPRT and VBT after EPRT were examined in the same category due to small number of patients receiving only EPRT. The patient and tumor characteristics were analyzed with chi-square and Fisher’s exact test. Survival estimates were calculated with Kaplan Meier and Log-rank tests (IBM statistical software v24).

Results: The median age was 62 years (range, 37-81 years). Total abdominal hysterectomy and bilateral salpingo-oophorectomy was performed in 99% of the patients. Pelvic or pelvic+paraaortic lymph node dissection (LND) was performed in all cases except 1 patient (14% and 85%, respectively). The median number of dissected LNs was 37 (range, 12-110). Lymphovascular invasion (LVI) was observed in 41 (59%) patients. Only VBT, only EPRT, and EPRT+VBT was performed in 55 (65%), 6 (7%), and 24 (28%) patients, respectively. Tumor and treatment characteristics were similar between groups, but frequency of chemotherapy administration and only pelvic LND was higher in EPRT±VBT group compared to VBT group (40% vs. 9%, p=0.001 and 30% vs. 7%, p=0.01, respectively). With a median follow-up of 92 months (range, 15-336 months), 5-y overall survival (OS), disease-free survival (DFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) rates were 84%, 70%, 73% and 82%, respectively. Five-y survival rates were similar between treatment groups (Tablo 1). LRR and DM was also similar (6% vs. 0%, p=0.170 and 13% vs. 3%, p=0.181, respectively). EPRT had no survival benefit in patients with LVI. In patients with LVI, LRR rates were 13% and 0% in VBT and EPRT groups, respectively (p=0.283). In all cohort, there was no ³grade 3 acute or late genitourinary or gastrointestinal toxicity. Late vaginal toxicity was observed in 5 (6%) patients and higher in EPRT group than VBT group (10% vs. 4%, p=0.340), although it did not reach statistical significance.

Conclusion: The survival outcomes of VBT alone and EPRT±VBT in patients with stage IB grade 3 endometroid type endometrial cancer were similar. However, in the presence of LVI, EPRT seems to be an accurate option in patients who had surgical staging due to high LRR rates of VBT alone. Abstract 3480 – Table 1: Survival rates according to the treatment groups