Table 1. Baseline Demographics and Patient Characteristics of the ≥1 LOT Cohort.

	≥1 LOT Cohort (n=1961)
Age (y), mean (SD)	66 (10)
Age group (y), n (%)
18–64	754 (38)
65–74	794 (40)
≥75	413 (21)
Year of 1L start, n (%)
2013	102 (5)
2014	178 (9)
2015	215 (11)
2016	247 (13)
2017	279 (14)
2018	271 (14)
2019	260 (13)
2020	250 (13)
2021–2022	159 (8)
Duration of follow-up from start of 1L (mo)
Mean (SD)	20.4 (20.9)
Median (Q1, Q3)	13 (5, 30)
Race, n (%)
Asian	37 (2)
Black or African American	328 (17)
White	1198 (61)
Other	241 (12)
Unknown/missing	157 (8)
US Census region, n (%)
Midwest	276 (14)
Northeast	240 (12)
South	794 (40)
West	206 (11)
Unknown/missing	445 (23)
Disease histology group, n (%)
Endometrioid	968 (49)
Non-endometrioid	993 (51)
FIGO stage at EC diagnosis, n (%)
I	566 (29)
II	87 (4)
III	386 (20)
IV	806 (41)
Unknown/missing	116 (6)
Baseline MSI and MMR status, n (%)
dMMR or MSI-H	60 (3)
pMMR or MSS	128 (7)
Unknown/not tested	1773 (90)
ECOG performance status, n (%)
0	235 (12)
1	143 (7)
2-4	29 (1)
Unknown/missing	1554 (79)
Received surgery for primary treatment of EC on or before LOT1 index date, n (%)
Yes	1098 (56)
No	73 (4)
Missing/undocumented	790 (40)
Received radiation for primary treatment of EC on or before LOT1 index date, n (%)
Yes	578 (30)
No	520 (27)
Missing/undocumented	863 (44)

Abbreviations: 1L, first-line; dMMR, mismatch repair deficient; EC, endometrial cancer; ECOG, Eastern Cooperative Oncology Group; FIGO, International Federation of Gynecology and Obstetrics; LOT, line of therapy; MMR, mismatch repair; MSI, microsatellite instability; MSI-H; microsatellite instability-high; MSS, microsatellite stability biomarker; pMMR, mismatch repair proficient; Q1, first quartile; Q3, third quartile.