Table 3.

Association of Endometrial Cancer Risk Factors With Specific Endometrial Cancer Histology

Risk Factor	No. of Controls	Cases
		Endometrioid			Adenocarcinoma NOS			Adenocarcinoma With Squamous Differentiation			Serous			Mixed Cell			Clear Cell			Mucinous
		No. of Cases	OR*	95% CI	No. of Cases	OR*	95% CI	No. of Cases	OR*	95% CI	No. of Cases	OR*	95% CI	No. of Cases	OR*	95% CI	No. of Cases	OR*	95% CI	No. of Cases	OR*	95% CI
Body mass index, kg/m2
< 25	18,400	2,428	1.00		1,914	1.00		260	1.00		208	1.00		122	1.00		74	1.00		67	1.00
25 to < 30	10,986	2,163	1.57	1.46 to 1.68	1,332	1.31	1.21 to 1.42	223	1.41	1.17 to 1.71	149	1.11	0.89 to 1.38	104	1.27	0.96 to 1.68	60	1.29	0.91 to 1.83	43	1.13	0.76 to 1.67
30 to < 35	4,078	1,319	2.56	2.35 to 2.80	830	2.41	2.19 to 2.67	145	2.32	1.86 to 2.89	94	1.73	1.34 to 2.25	65	1.71	1.23 to 2.37	42	2.46	1.65 to 3.68	31	2.10	1.35 to 3.28
35 to < 40	1,255	753	4.75	4.22 to 5.34	412	4.05	3.52 to 4.66	82	4.18	3.15 to 5.54	32	1.80	1.20 to 2.68	33	2.79	1.83 to 4.25	10	1.94	0.98 to 3.87	17	3.36	1.90 to 5.96
≥ 40	593	583	6.88	5.95 to 7.96	342	7.17	6.05 to 8.49	67	7.76	5.56 to 10.82	25	2.85	1.80 to 4.52	22	3.49	2.06 to 5.90	10	4.36	2.16 to 8.82	8	3.29	1.51 to 7.19
P trend			< .0001			< .0001			< .0001			< .0001			< .0001			< .0001			< .0001
Body mass index, per 2 kg/m2	35,312	7,246	1.21	1.20 to 1.22	4,830	1.20	1.18 to 1.21	777	1.20	1.17 to 1.23	508	1.10	1.07 to 1.14	346	1.13	1.09 to 1.18	196	1.14	1.08 to 1.20	166	1.16	1.10 to 1.22
Age at menarche, years
< 11	1,633	508	1.00		285	1.00		51	1.00		40	1.00		28	1.00		12	1.00		16	1.00
11-12	7,332	1,740	0.87	0.76 to 0.99	926	0.94	0.80 to 1.10	166	0.74	0.53 to 1.05	134	0.74	0.51 to 1.08	86	0.57	0.36 to 0.91	41	0.76	0.39 to 1.47	34	0.53	0.28 to 0.97
13-14	21,563	3,963	0.83	0.73 to 0.94	3,104	0.90	0.77 to 1.04	461	0.71	0.52 to 0.98	283	0.66	0.47 to 0.95	183	0.57	0.37 to 0.89	113	0.76	0.41 to 1.41	105	0.57	0.33 to 0.99
≥ 15	4,784	1,035	0.67	0.58 to 0.78	515	0.77	0.65 to 0.92	99	0.59	0.41 to 0.86	51	0.48	0.31 to 0.75	49	0.50	0.30 to 0.84	30	0.83	0.41 to 1.69	11	0.32	0.14 to 0.70
P trend			< .0001			.002			.01			.001			.04			.81			.03
Parity
0	4,593	1,295	1.00		963	1.00		193	1.00		83	1.00		67	1.00		31	1.00		36	1.00
1	4,528	1,271	0.73	0.65 to 0.81	621	0.81	0.71 to 0.91	107	0.54	0.41 to 0.70	74	1.00	0.72, 1.40	47	0.63	0.42 to 0.95	25	0.81	0.46 to 1.42	26	0.82	0.48 to 1.40
2	10,147	2,159	0.68	0.62 to 0.75	1,347	0.71	0.64 to 0.78	222	0.48	0.38 to 0.59	142	0.75	0.57 to 1.00	108	0.55	0.39 to 0.77	48	0.70	0.44 to 1.13	46	0.63	0.40 to 0.99
3	12,119	1,970	0.56	0.51 to 0.62	1,519	0.60	0.54 to 0.66	197	0.39	0.32 to 0.49	150	0.60	0.45 to 0.80	81	0.51	0.35 to 0.72	62	0.71	0.45 to 1.11	49	0.53	0.34 to 0.83
≥ 4	3,925	551	0.42	0.37 to 0.47	380	0.41	0.36 to 0.48	58	0.25	0.18 to 0.35	59	0.55	0.38 to 0.78	43	0.54	0.35 to 0.84	30	0.73	0.43 to 1.24	9	0.30	0.14 to 0.65
P trend			< .0001			< .0001			< .0001			< .0001			.0007			.19			.0002
Oral contraceptive use
Never	20,785	4,139	1.00		3,378	1.00		494	1.00		306	1.00		191	1.00		131	1.00		103	1.00
Ever	14,527	3,107	0.78	0.73 to 0.84	1,452	0.67	0.62 to 0.73	283	0.64	0.53 to 0.78	202	0.87	0.70 to 1.07	155	0.54	0.40 to 0.72	65	0.66	0.46 to 0.94	63	0.65	0.44 to 0.95
Cigarette smoking†
Never	18,815	4,485	1.00		2,754	1.00		453	1.00		302	1.00		230	1.00		110	1.00		81	1.00
Former	10,900	2,025	0.83	0.78 to 0.89	1,421	0.91	0.84 to 0.98	202	0.83	0.69 to 0.99	145	0.76	0.61, 0.94	82	0.62	0.47 to 0.81	47	0.78	0.54 to 1.11	57	1.14	0.80 to 1.62
Current	5,152	558	0.61	0.55 to 0.68	456	0.64	0.57 to 0.71	112	0.88	0.70 to 1.10	46	0.66	0.48 to 0.91	34	0.53	0.36 to 0.78	28	1.13	0.73 to 1.73	8	0.41	0.19 to 0.85
Pack-years of smoking‡
Never	13,693	2,988	1.00		2,246	1.00		412	1.00		190	1.00		177	1.00		76	1.00		58	1.00
< 20	5,383	772	0.80	0.73 to 0.89	724	0.93	0.84 to 1.03	143	0.79	0.64 to 0.98	54	0.79	0.57 to 1.09	52	0.59	0.42 to 0.83	28	0.98	0.62 to 1.54	19	0.81	0.48 to 1.39
≥ 20	3,594	465	0.68	0.60 to 0.77	544	0.71	0.64 to 0.80	100	0.80	0.63 to 1.02	46	0.83	0.59 to 1.17	23	0.49	0.31 to 0.78	17	0.82	0.47 to 1.41	14	0.77	0.42 to 1.41
P trend			< .0001			< .0001			.02			.17			.0002			.50			.33
Diabetes§
No	26,575	4,967	1.00		3,100	1.00		453	1.00		314	1.00		158	1.00		122	1.00		109	1.00
Yes	2,077	929	1.28	1.16 to 1.42	417	1.25	1.10 to 1.43	56	1.04	0.76 to 1.41	63	1.33	0.98 to 1.81	41	1.93	1.30 to 2.85	19	1.23	0.73 to 2.09	13	1.37	0.73 to 2.55

Abbreviations: NOS, not otherwise specified; OR, odds ratio.

^*Stratified by age, study, and race/ethnicity and mutually adjusted for body mass index, 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.