2845 - Effect of Adjuvant Treatment Modality on Survival Outcomes by FIGO Grade in Locally Advanced Endometrial Cancer

Purpose/Objective(s):

Chemotherapy for locally advanced endometrial cancer in the adjuvant setting improves survival, while radiation therapy has impact on locoregional control. There is limited data on the efficacy of adjuvant therapy by grade. We hypothesized that the effect of adjuvant treatment modality on survival outcomes would be different by FIGO grade.

Materials/Methods: Data from the National Cancer Database (NCDB) was accessed for patients with cancer of Uterine Corpus diagnosed from 2004-2020. We selected locally advanced endometrial cancer patients who received surgery. Adjuvant treatment modality was categorized as none, chemotherapy only (CO), radiation only (RO), sequential chemotherapy and radiation (SCRT), and concurrent chemotherapy and radiation (CCRT), and no adjuvant treatment (NA). Kaplan Meier with log rank testing was used for overall survival (OS) analysis. Cox PH regression model was used for univariable (UVA) and multivariable analysis (MVA).

Results:

Of 25,281 patients with median follow up 67.0 months, FIGO grade was 1 (G1), 2 (G2), 3 (G3), and unknown in 20.9%, 32.5%, 29.2%, and 17.4% respectively. 2-year OS was 81.5% (95% CI 80.63-82.34%) with CO, 81.91% (95% CI 80.40-83.32%) with RO, 90.23% (95% CI 89.49-90.92%) with SCRT, 86.58% (95% CI 84.62-88.31%) with CCRT, and 75.95% (95% CI 73.86-76.01%) with no adjuvant treatment. MVA demonstrated facility type, age, race, Hispanic ethnicity, Charlson Deyo score, pelvic nodal involvement, FIGO grade, lymphovascular invasion, and adjuvant treatment modality were significantly predictive of OS. Interaction testing found a significant difference in the effect of adjuvant treatment modality by grade (p=0.0179). On stratification of MVA model by grade (Table 1), G2 and G3 patients demonstrated a risk reduction with SCRT compared to CO.

Table 1. Stratified MVA Models

*p<0.05

Conclusion:

Survival outcomes are significantly different by FIGO grade and adjuvant treatment type. FIGO grade 2 & 3 patients may derive a greater benefit with SCRT as opposed to chemotherapy alone. Additional molecular analysis is needed to determine appropriate patient selection for adjuvant therapy.

	HR (95% CI) for death
Adjuvant Treatment Modality	Entire Cohort	FIGO G1	FIGO G2	FIGO G3
CO	1.00	1.00	1.00	1.00
RO	1.56 (1.05-2.31)*	1.68 (1.11-2.53)*	1.09 (0.81-1.49)	0.91 (0.69-1.19)
SCRT	0.92 (1.06-2.31)	0.97 (0.70-1.33)	0.73 (0.59-0.89)*	0.70 (0.60-0.82)*
CCRT	0.61 (0.32-1.19)	0.63 (0.32-1.22)	0.71 (0.5-1.0)	0.88 (0.67-1.17)
NA	1.51 (1.09-2.08)*	1.47 (1.06-2.04)*	1.44 (1.19-1.75)*	1.14 (0.97-1.33)