MTHFR C677T and postmenopausal breast cancer risk by intakes of one-carbon metabolism nutrients: a nested case-control study

Table 1 Characteristics of postmenopausal breast cancer cases and controls, VITAL study *

	Cases (n = 318)	Controls (n = 647)	P value †
Demographics
Age, years (mean ± SD)	64.4 ± 6.88	64.2 ± 6.86	0.67
White,%	95.0	95.1	0.95
Family history/breast-related procedures
Mother or sister with breast cancer,%	18.6	15.6	0.25
Mammography in past 2 years,%	93.1	93.7	0.73
Prior breast biopsy,%	28.0	21.8	0.03
Reproductive factors
Early age at menarche,% <12 years	20.1	18.1	0.44
Nulliparous, %	12.9	9.74	0.14
Age at first birth, years (mean ± SD) ‡	24.1 ± 4.85	23.3 ± 4.39	0.05
Parity, number of births (mean ± SD) ‡	2.60 ± 1.09	2.86 ± 1.21	<0.01
Age at menopause, years (mean ± SD)	47.9 ± 5.37	47.4 ± 5.84	0.37
Ever use of estrogen plus progestin postmenopausal hormones, %	48.1	35.2	<0.01
Lifestyle/anthropomorphic factors
Height, in (mean ± SD)	64.9 ± 2.65	64.8 ± 2.61	0.36
Baseline BMI, kg/m² (mean ± SD)	26.9 ± 5.63	27.2 ± 5.61	0.21
Total physical activity, MET-hour/week (mean ± SD)	9.44 ± 11.9	10.1 ± 13.9	0.90
Dietary factors
Total folate, DFE/day (mean ± SD) §	819 ± 420	856 ± 419	0.15
Dietary methionine, g/day (mean ± SD)	1.43 ± 0.57	1.48 ± 0.61	0.32
Total B₂, mg/day (mean ± SD) §	2.53 ± 1.21	2.64 ± 1.28	0.16
Total B₆, mg/day (mean ± SD) §	10.1 ± 30.3	7.97 ± 15.4	0.38
Total B₁₂, μg/day (mean ± SD) §	22.5 ± 40.2	18.9 ± 29.3	0.57
Alcohol, g/day (mean ± SD)	5.96 ± 8.91	4.76 ± 9.76	0.03
Multivitamin use, days/week over 10 years (mean ± SD)	3.29 ± 2.90	3.50 ± 2.93	0.25

* Cases and controls were originally 2:1 matched on age and race; the number of cases and controls are not exactly 2:1 because women who were premenopausal or who did not have MTHFR genotype data were excluded.
†Wilcoxon rank-sum test for continuous variables and chi-square test for dichotomous variables
‡Among parous women only
§Intake from dietary plus supplemental sources

ISSN: 1465-542X