Relationship of serum estrogens and estrogen metabolites to postmenopausal breast cancer risk: a nested case-control study

Table 1 Distribution of cases and controls by breast cancer risk factors and matching characteristics; Columbia Missouri Serum Bank Cohort Breast Cancer Case-Control Study

			Cases		Controls
			Number	%	Number	%
			215	100	215	100
Breast cancer risk factors
Family history of breast cancer
		yes	67	31.2	55	25.6	P = 0.199
	BMI
		<25	89	41.4	95	44.2
		25-29	87	40.5	80	37.2
		30+	39	18.1	40	18.6	P = 0.778
		Mean (SD)	26.2 (+/- 3.9)		26.5 (+/- 4.8)
	Ever smoke
		yes	58	27.0	56	26.0	P = 0.270
	Age at menarche
		<12	28	13.0	30	14.0
		12	58	27.0	49	22.8
		13	71	33.0	75	34.9
		14+	58	27.0	61	28.4	P = 0.799
Reproductive history
Never pregnant			36	16.7	34	15.8	P = 0.811
Number of prenancies^a
		1-2	102	57.0	83	45.9
		3-4	57	31.8	66	36.5
		5+	20	11.2	32	17.7	P = 0.002
Age at first pregnancy^a
		<20	24	13.4	34	18.8
		20-24	98	54.7	85	47.0
		25-29	38	21.2	41	22.7
		30+	19	10.6	21	11.6	P = 0.415
		mean (SD)	23.9 (+/- 4.2)		24.2 (+/-4.7)
^aamong parous women
Age at menopause
		<45	40	18.6	38	17.7
		45 to 49	53	24.7	63	29.3
		50 to 54	89	41.4	91	42.3
		55+	20	9.3	10	4.7
		unknown	13	6.0	13	6.0	P = 0.371
Years to breast cancer diagnosis (from blood draw)
		<1	7	3.3
		1 to <2	10	4.7
		2 to <3	18	8.4
		3 to <4	21	9.8
		4-<5	9	4.1
		5+	150	69.8
Matching factors
Age at blood collection
		<55	60	27.9	62	28.8
		55 to 59	58	27.0	49	22.8
		60 to 64	45	20.9	43	20.0
		65 to 69	33	15.3	35	16.3
		70+	19	8.8	26	12.1
Type of menopause
		Natural	154	71.6	152	70.7
		Ovariectomy	26	12.1	28	13.0
		Hysterectomy after age 54	22	10.2	22	10.2
		Early hysterectomy <age 54	13	6.0	13	6.0
Years between menopause and blood collection
		<1	6	2.8	6	2.8
		1 to <2	15	7.0	17	7.9
		2 to <3	10	4.7	8	3.7
		3 to <4	9	4.2	9	4.2
		4+	175	81.4	171	79.5
		unknown			4	1.9
Time of blood collection
		11 am to 1 pm	82	38.1	80	37.2
		2 pm to 5 pm	62	28.8	60	27.9
		6 pm to 10 pm	71	33.0	71	33.0
		unknown			4	1.9

ISSN: 1465-542X