2746 - Trends in Management of Node Positive Endometrial Cancer after GOG 258 and PORTEC 3

10:45am - 12:00pm PT

Hall F

Screen: 10

POSTER

Presenter(s)

Marie Fort, MD - Duke University Hospital, Durham, NC

M. Fort, D. N. Ayala-Peacock, and J. P. Chino; Department of Radiation Oncology, Duke University Medical Center, Durham, NC

Purpose/Objective(s):

Stage IIIC (node positive) endometrial cancer is most often managed with chemotherapy (CT), radiation (RT), or a combination (CTRT) after surgery. PORTEC3 (RT vs CTRT) and GOG 258 (CT vs CTRT) enrolled node positive cohorts and were both initially presented in 2017 and published in 2018 and 2019 respectively. PORTEC 3 showed benefit for CTRT vs RT, while GOG 258 showed no difference in disease free survival between CT and CTRT. We aim to establish trends in management of Stage IIIC endometrial cancer since presentation and publication of GOG 258 and PORTEC 3.

Materials/Methods:

The Surveillance, Epidemiology, and End Results (SEER) 17 Registries Research plus Database was used to identify all patients from 2015-2021 with Stage IIIC1 and 2 uterine cancer and the treatment received. Treatments were classified as any radiation therapy (RT), external beam radiation therapy (EBRT), vaginal brachytherapy (VBT), chemotherapy (CT), and combined chemotherapy and radiation (CTRT). Chi-square tests were used for association of treatment utilization and two time periods: 2015-2017 (pre-presentation/publication) and 2019-2021 (post publication). Statistical software was used to perform data aggregation and analysis. Significance assumed at p = 0.05.

Results:

6091 patients were identified, 2921 patients from 2015-2017 and 3170 patients from 2019-2021. Patients diagnosed from 2015-2017 were more likely to be treated with any form of RT than patients diagnosed in 2019-2021 (64.5% vs 61.2%, p=0.008). However, there was no significant difference in utilization of EBRT (54.4% vs 52.1%, p=0.072) or VBT (7.6% vs 7.4%, p=0.714) or treatment with RT alone (5.3% vs 6.1%, p=0.192). There was no significant change in overall CT utilization between the two groups (81.9 vs 82.0%, p=0.947). However, there was a significant increase in the ratio of patients receiving CT alone from 2019-2021 (26.7%) than patients diagnosed from 2015-2017 (22.7%, p<0.001). There was a corresponding significant decrease in treatment with combined CT and RT between the two groups (59.2% vs 55.1%, p=0.001).

Conclusion:

The use of radiation therapy declined after publication of PORTEC 3 and GOG 258 (-5% relative), while the use of chemotherapy as monotherapy increased (+15% relative). This is suggestive that the results of GOG 258 have shifted practice patterns in the US more than PORTEC 3. This work is limited by known under-ascertainment issues for radiation therapy in SEER datasets, however, if these rates are constant over time, trends are expected to remain valid. It is also uncertain how the COVID 19 pandemic affected the relatively utilization of post-surgical treatments, and if these trends have continued since 2021. Further work to better identify those patients who might benefit most from post-surgical radiation therapy is indicated to prevent a concomitant increase in local recurrence with chemotherapy alone.