Table 1.

Comparison of cases and controls on demographics and selected endometrial cancer risk factors

	Cases (n = 1,204)	Controls (n = 1,212)	P
Age (mean ± SD)	54.9 ± 8.5	55.1 ± 8.5	0.75*
Education (%)
No formal education	7.9	11.0
Elementary education	14.1	12.9
Middle and high school	62.9	63.3
Professional, college and above	15.1	12.8	0.03^†
Marital status (%)
Unmarried	1.5	1.1
Married or cohabiting	87.6	87.6
Separated/divorced/widowed	10.9	11.3	0.63^†
Family income in previous year, yuan (%)
<10,000	11.6	11.2
10,000-14,999	21.7	21.3
15,000-19,999	19.9	18.5
20,000-29,999	21.9	25.6
≥30,000	24.9	23.4	0.33^†
No. pregnancies (%)
Never	7.4	3.6
1	16.9	13.8
2	25.2	26.0
3	22.3	24.9
4	16.9	17.6
≥5	11.3	14.1	<0.01^†
Cancer among first-degree relatives (%)^‡	8.5	4.4	<0.01^†
Natural menopause (%)	97.0	99.1	<0.01^†
Oral conceptive use (%)	18.5	24.9	<0.01^†
Hormone replacement therapy (%)	4.4	4.0	0.66^†
Regular exercise (%)	28.7	33.5	0.01^†
Age at menarche^§	14.0 (13.0, 16.0)	15.0 (13.0, 16.0)	<0.01*
Age at menopause (among postmenopausal women)^§	50.3 (48.6, 52.5)	49.6 (47.3, 51.1)	<0.01*
Years of menstruation^§	33.3 (30.1, 36.1)	31.5 (28.2, 34.4)	<0.01*
BMI^§	25.2 (22.9, 28.1)	23.5 (21.4, 26.0)	<0.01*
Waist-to-hip circumference ratio^§	0.84 (0.81, 0.87)	0.81 (0.78, 0.85)	<0.01*

NOTE: Subjects with missing values were excluded from the analysis.
↵* Nonvariable test on continuous variables.
↵† χ² test was used to compare the distribution of categorical variables.
↵‡ Family history of colorectal, endometrial, or breast cancer among first-degree relatives.
↵§ Median (25th, 75th percentile) is presented.