3761 - Impact of the 2023 ASTRO Endometrial Clinical Practice Guidelines on a Single Institution's Use of Adjuvant Therapy for Early-Stage Disease
Presenter(s)
S. Slankard1, A. C. Inda1, P. Mitra1, J. V. Kuo1, G. K. Harada2, and E. Healy1; 1University of California, Irvine - Department of Radiation Oncology, Orange, CA, 2Department of Radiation Oncology, University of California - Irvine, Orange, CA
Purpose/Objective(s): Adjuvant radiation therapy for early-stage endometrial cancer has historically been guided by classic legacy studies conducted by PORTEC and GOG. In 2023, ASTRO released updated clinical practice guidelines that account for more recent data and more modern surgical techniques. These guidelines introduced a treatment algorithm based on 2009 FIGO staging to simplify adjuvant radiation therapy decisions for both endometrioid and high-risk histologies. This study evaluates impact of the 2023 guidelines and role in standardizing recommendations for early-stage disease.
Materials/Methods: We retrospectively identified all patients treated for endometrial cancer at our institution between 1/1/2018 and 7/27/2023. We excluded patients with FIGO 2009 Stage III–IV disease, lack of surgical staging, recurrent disease, and uterine sarcomas. Adjuvant therapy decisions were compared to the 2023 ASTRO updated guideline recommendations for congruence. Cases were scored as "escalated" where radiotherapy was given though not guideline-indicated or pelvic external beam radiation therapy (EBRT) was used when only vaginal brachytherapy (VBT) was indicated; "de-escalation" was defined as omitting indicated therapy. Per the 2023 guidelines’ conditional recommendations, molecular markers were not used to modify risk-stratification. Guideline congruency was compared before and after the January 2023 publication date using a one-tailed t-test.
Results: Of the 475 patients meeting inclusion criteria, 417 (87.8%) were treated before January 2023 and 58 (12.2%) after. The median age was 60 years (range: 23–95). Disease stages included FIGO IA (71.2%), IB (21.7%), and II (7.2%). Histology was predominantly endometrioid (78.3%), with 44.2% of the total cohort presenting with high-grade disease. Adjuvant radiation was administered to 167 patients (35.2%), consisting of VBT (65.3%), EBRT (12.6%), or both (22.2%). Overall congruency with 2023 ASTRO recommendations increased from 78.3% (n=318) pre-implementation to 84.5% (n=49) post-implementation. Treatment escalation was indicated in 19.4% (n=81) of patients before versus 13.8% (n=8) after, while treatment de-escalations were indicated in 4.3% (n=18) before versus 1.7% (n=1) after. Implementation was associated with significantly increased treatment consistency (p < 0.05) among high-risk subgroups, specifically those with high-risk histology (25.9%, n=15/58 vs. 52.9%, n=9/17) and extensive LVSI (46.2%, n=6/13 vs. 81.8%, n=9/11).
Conclusion: These results demonstrate high baseline treatment consistency that further improved following the release of the 2023 ASTRO guidelines. This improvement was most significant for patients with high-risk features, such as extensive LVSI and high-risk histologies, suggesting the guidelines effectively standardized care for the more complex early-stage cases.