Table 4.

Association of Endometrial Cancer Risk Factors With Type I and Type II Tumors

Risk Factor	No. of Controls	Cases						P heterogeneity
		Type I*			Type II†
		No. of Cases	OR‡	95% CI	No. of Cases	OR‡	95% CI
Mean age at diagnosis, years		12,853	62.7		854	64.8		< .0001
Body mass index, kg/m2
< 25	18,400	4,602	1.00		330	1.00
25 to < 30	10,986	3,718	1.45	1.37 to 1.53	253	1.16	0.98 to 1.38
30 to < 35	4,078	2,294	2.52	2.35 to 2.69	159	1.73	1.40 to 2.12
35 to < 40	1,255	1,247	4.45	4.05 to 4.89	65	2.15	1.60 to 2.88
≥ 40	593	992	7.14	6.33 to 8.06	47	3.11	2.19 to 4.44
P trend			< .0001			< .0001		< .0001
Body mass index, per 2 kg/m2	35,312	12,853	1.20	1.19 to 1.21	854	1.12	1.09 to 1.14	< .0001
Age at menarche, years
< 11	1,633	844	1.00		68	1.00
11-12	7,332	2,832	0.89	0.80 to 0.99	220	0.67	0.50 to 0.90
13-14	21,563	7,528	0.85	0.77 to 0.94	466	0.62	0.47 to 0.82
≥ 15	4,784	1,649	0.71	0.63 to 0.80	100	0.50	0.35 to 0.70
P trend			< .0001			.0002		.11
Parity
0	4,593	2,451	1.00		150	1.00
1	4,528	1,999	0.74	0.68 to 0.81	121	0.84	0.65 to 1.09
2	10,147	3,728	0.67	0.63 to 0.72	250	0.67	0.54 to 0.83
3	12,119	3,686	0.56	0.52 to 0.60	231	0.56	0.45 to 0.70
≥ 4	3925	989	0.40	0.36 to 0.44	102	0.54	0.41 to 0.72
P trend			< .0001			< .0001		.31
Oral contraceptive use
Never	20,785	8,011	1.00		497	1.00
Ever	14,527	4,842	0.73	0.69 to 0.77	357	0.74	0.62 to 0.89	.17
Cigarette smoking§
Never	18,815	7,692	1.00		532	1.00
Former	10,900	3,648	0.87	0.82 to 0.91	227	0.70	0.59 to 0.83	.11
Current	5,152	1,126	0.64	0.60 to 0.70	80	0.60	0.46 to 0.77	.79
Pack-years of smoking‖
Never	13,693	5,646	1.00		367	1.00
< 20	5,383	1,639	0.86	0.80 to 0.92	106	0.69	0.55 to 0.87
≥ 20	3,594	1,109	0.71	0.65 to 0.77	69	0.68	0.52 to 0.90
P trend			< .0001			.0006		.44
Diabetes¶
No	26,575	8,520	1.00		472	1.00
Yes	2,077	1,402	1.27	1.17 to 1.38	104	1.53	1.19 to 1.95	.14

Abbreviation: OR, odds ratio.

^*Type I included endometrioid adenocarcinoma, adenocarcinoma not otherwise specified, and adenocarcinoma with squamous differentiation.

^†Type II included serous and mixed cell adenocarcinoma.

^‡Stratified by age, study and race/ethnicity and mutually adjusted for BMI, age at menarche, parity, oral contraceptive use, menopausal status, menopausal hormone use, and smoking status.

^§Based on 23 studies with smoking data.

^‖Based on 18 studies with pack-years of smoking data.

^¶Based on 19 studies with diabetes data.