Prospectively measured triiodothyronine levels are positively associated with breast cancer risk in postmenopausal women

Table 2 Distribution of potential risk factors for breast cancer according to serum TSH level

Factor	TSH quartile
	1	2	3	4	All
	N = 647	N = 528	N = 793	N = 710	N = 2,678
	Column percent (TSH levels in italics)
TSH (mIU/l)
period I	<1.50	1.60 to 2.00	2.10 to 3.00	≥3.10
period II	<0.90	1.00 to 1.30	1.40 to 2.00	≥2.10
Age
<50	21.5	42.6	40.9	24.9	32.3
>50	78.5	57.4	59.1	75.1	67.7
Premenopausal	24.0	41.9	41.5	27.3	33.6
Peri/postmenopausal	76.0	58.1	58.5	72.7	66.4
HRT in peri/postmenopausal	17.3	20.8	17.2	13.0	16.6
missing	0.2	-	-	-	0.1
Nulliparity	13.9	13.1	18.0	18.2	16.1
missing	1.4	1.9	0.5	0.3	0.9
OC-use	3.7	8.7	8.7	4.4	6.3
missing	1.7	2.1	0.8	0.3	1.1
Menarche <12 years	13.4	12.5	13.0	12.0	12.7
missing	2.3	3.6	1.0	0.6	1.7
Smoking
never	42.2	41.9	47.9	51.0	46.2
current	36.0	36.9	31.9	29.7	33.3
ex	20.2	19.3	19.7	18.9	19.5
missing	1.5	1.9	0.5	0.4	1.0
Alcohol consumption
nothing	17.0	12.3	14.2	16.5	15.1
less than every week	59.4	53.2	57.8	60.0	57.8
every week	21.5	30.7	26.5	23.0	25.2
missing	2.2	3.8	1.5	0.6	1.9
BMI
<20	10.0	11.6	9.1	7.3	9.3
≥20 <25	53.3	50.8	57.9	52.0	53.8
≥25 <30	26.9	27.3	23.8	28.9	26.6
≥30	9.7	10.4	9.2	11.8	10.3
Height
≤ 160	30.3	26.9	29.5	33.9	30.4
>160 ≤ 165	32.8	29.5	31.8	33.2	32.0
>165 ≤ 170	26.0	27.5	25.3	21.7	24.9
>170	11.0	16.1	13.4	11.1	12.7
Education
<12 years	58.6	54.4	55.1	61.0	57.4
12 years	23.3	24.6	26.4	22.0	24.1
>12 years	14.2	18.8	14.2	13.2	14.9
missing	3.9	2.3	4.3	3.8	3.7
Married	45.0	49.6	51.2	54.9	50.4
missing	19.6	25.0	7.6	4.2	13.0

Abbreviations: TSH, thyrotropin; HRT, hormone replacementtherapy; OC, oral contraceptives; BMI, body mass index.

ISSN: 1465-542X