Table 3. Adjusted ORs and 95% CIs of risk factors for histological subtypes of uterine sarcoma, based on a pooled analysis of 15 observational studies in the E2C2.

			Histological subtypes of uteirne sarcoma
	Controls		Endometrial stromal sarcoma			Leiomyosarcoma
Characteristicsa	n=28 829		n=98			n=82
	n	%	n	%	OR (95% CI)b	n	%	OR (95% CI)b	P-heterogeneityc
Body mass index									0.39
Normal weight (<25 kg m−2)	14 244	49.4	42	42.9	1.00	33	40.2	1.00
Overweight (25–30 kg m−2)	9044	31.4	26	26.5	1.02 (0.62, 1.68)	20	24.4	0.90 (0.51, 1.60)
Obese (⩾30 kg m−2)	4932	17.1	27	27.6	1.74 (1.03, 2.93)	23	28.0	1.56 (0.88, 2.77)
P-trendd					0.07			0.26
Age at menarche									0.10
<11	1252	4.3	7	7.1	1.00	6	7.3	1.00
11–12	10 408	36.1	39	39.8	0.88 (0.39, 2.01)	38	46.3	1.10 (0.44, 2.73)
13–14	12 808	44.4	42	42.9	0.88 (0.38, 2.01)	27	32.9	0.75 (0.29, 1.91)
⩾15	4103	14.2	8	8.2	0.60 (0.21, 1.71)	9	11.0	1.01 (0.34, 2.98)
P-trendd					0.41			0.44
Parity									0.40
Nulliparous	3234	11.2	11	11.2	1.00	12	14.6	1.00
Parous	24 912	86.4	81	82.6	0.97 (0.51, 1.83)	65	79.3	0.76 (0.40, 1.44)
Number of live births (among parous women)									0.17
1	3621	14.5	8	9.9	1.00	13	20.0	1.00
2	7805	31.3	26	32.1	1.59 (0.71, 3.56)	19	29.2	0.71 (0.35, 1.46)
3–4	10 040	40.3	38	46.9	2.02 (0.91, 4.45)	28	43.1	0.78 (0.39, 1.54)
⩾5	3446	13.8	9	11.1	1.36 (0.50, 3.67)	5	7.7	0.35 (0.12, 1.03)
P-trendd					0.31			0.12
Menopausal status									0.22
Premenopausal	4015	13.9	23	23.5	1.00	25	30.5	1.00
Peri-menopausal	281	1.0	0	0.0	NE	2	2.4	0.73 (0.12, 4.41)
Postmenopausal	23 826	82.6	70	71.4	0.85 (0.42, 1.72)	50	61.0	0.35 (0.16, 0.75)
Menopausal hormone usee									0.98
Never	13 412	58.5	26	40.6	1.00	27	54.0	1.00
Ever	9287	40.5	37	57.8	1.53 (0.54, 4.31)	23	46.0	0.80 (0.22, 2.98)
Menopausal oestrogen-alone usef									0.97
Never	15 019	76.9	40	63.5	1.00	32	78.0	1.00
Ever	2878	14.7	12	19.0	1.02 (0.29, 3.61)	6	14.6	1.63 (0.18, 14.95)
Menopausal oestrogen plus progesting									0.72
Never	11 390	69.7	26	47.3	1.00	21	55.3	1.00
Ever	3424	20.9	17	30.9	1.43 (0.35, 5.76)	13	34.2	0.79 (0.08, 7.90)
Oral contraceptive use									0.54
Never	17 894	62.1	52	53.1	1.00	44	53.7	1.00
Ever	10 670	37.0	44	56.4	0.85 (0.53, 1.34)	36	43.9	0.72 (0.44, 1.19)
Smoking statush									0.22
Never	14 926	52.6	50	56.2	1.00	41	50.6	1.00
Former	8504	30.0	21	23.6	0.66 (0.39, 1.11)	28	34.6	1.15 (0.70, 1.90)
Current	4133	14.6	16	18.0	1.09 (0.61, 1.94)	9	11.1	0.75 (0.36, 1.56)
History of diabetesi									0.65
No	15 889	62.8	47	64.4	1.00	33	48.5	1.00
Yes	1583	6.3	11	15.1	2.28 (1.02, 5.12)	10	14.7	1.91 (0.77, 4.77)

Abbreviations: CI=confidence interval; E2C2=Epidemiology of Endometrial Cancer Consortium; NE=not estimable (due to zero cells); OR=odds ratio.

^aMissing values were excluded from presentation, but included as a separate category in logistic regression analysis.

^bPolytomous logistic regression models adjusted for age, race, BMI, age at menarche, menopausal status, menopausal oestrogen plus progestin, menopausal oestrogen use, oral contraceptive use, smoking status, history of diabetes, and site.

^cP-values for tumour heterogeneity are based on case-only multivariable-adjusted logistic regression models using endometrial stromal sarcoma cases as the ‘controls'.

^dP-values for trend caluclated with the variable modelled ordinally.

^eAmong postmenopausal women.

^fAmong postmenopausal women in 12 studies with menopausal oestrogen use data.

^gAmong postmenopausal women in 10 studies with menopausal oestrogen plus progestin use data.

^hAmong 14 studies with smoking data.

ⁱAmong 13 studies with diabetes data.