Table 4.

ORs and 95% CIs of invasive breast cancer across tertiles of dietary folate equivalents in strata of MTHFR polymorphisms among cases and controls from the MDC cohort

All women (45-73 y of age, n = 1,614)Cases/controlsTertiles of dietary folate equivalents*
P for trend
1 (179)2 (240)3 (378)(P for interaction)
Strata of MTHFR 677C>T§
    CC255/5301.001.01 (0.69-1.49)0.90 (0.61-1.31)0.81
    CT235/4501.01 (0.69-1.49)1.06 (0.72-1.57)0.96 (0.63-1.44)0.66
    TT50/910.68 (0.32-1.44)1.00 (0.50-2.00)1.86 (0.99-3.50)0.01
    CT+TT285/5410.96 (0.66-1.39)1.05 (0.72-1.53)1.10 (0.75-1.62)0.63
(0.35)
Strata of MTHFR 1298A>C§
    AA242/4841.001.34 (0.89 2.00)1.42 (0.96-2.12.)0.07
    AC242/4801.41 (0.95-2.10)1.39 (0.92-2.09)1.12 (0.74-1.69)0.19
    CC57/1051.95 (1.01-3.75)1.14 (0.60-2.19)1.32 (0.69-2.53)0.83
    AC+CC299/5851.49 (1.02-2.17)1.34 (0.90-1.97)1.15 (0.78-1.71)0.15
(0.03)
Strata of MTHFR combined genotypes§
    677 CC, 1298 AA68/1651.001.07 (0.51-2.27)0.84 (0.40-1.75)0.95
    677CC, 1298 AC130/2571.08 (0.55-2.12)1.36 (0.68-2.70)1.14 (0.58-2.25)0.78
    677CC, 1298CC57/1051.78 (0.79-4.00)1.02 (0.46-2.30)1.20 (0.53-2.68)0.83
    677 CC, 1298 AC/CC187/3621.24 (0.65-2.36)1.24(0.65-2.38)1.16 (0.61-2.21)0.93
    677CT, 1298AA0.90 (0.45-1.80)1.28 (0.65-2.55)1.42 (0.70-2.84)0.13
    677CT, 1298AC112/2231.54 (0.78-3.06)1.16 (0.58-2.31)0.86 (0.41-1.77)0.01
    677TT, 1298AA50/910.79 (0.32-1.95)1.17 (0.50-2.74)2.17 (0.97-4.84)0.01
    677 CT/TT, 1298 AA172/3180.88 (0.45-1.70)1.25 (0.65-2.41)1.63 (0.85-3.14)0.01
Women below 55 y of age (n = 684)Cases/controlsTertiles of dietary folate equivalents*
P for trend


1 (179)
2 (240)
3 (378)
(P for interaction)
Strata of MTHFR 677C>T§
    CC114/2071.001.12 (0.62-2.02)0.90 (0.49-1.64)0.90
    CT92/2060.85 (0.46-1.57)0.84 (0.46-1.52)0.76 (0.40-1.46)0.73
    TT22/430.27 (0.06-1.28)1.57 (0.59-4.2)1.13 (0.45-2.82)1.00
    CT+TT114/2490.75 (0.41-1.36)0.93 (0.53-1.64)0.84 (0.46-1.53)0.86
(0.58)
Strata of MTHFR 1298A>C§
    AA95/2181.001.93 (1.00-3.71)1.69 (0.87-3.28)0.25
    AC106/2052.08 (1.07-4.01)1.92 (0.98-3.75)1.64 (0.82-3.28)0.44
    CC28/344.08 (1.45-11.49)2.76 (1.04-7.29)2.59 (0.79-8.52)0.55
    AC+CC134/2392.34 (1.25-4.41)2.07 (1.09-3.91)1.78 (0.91-2.65)0.34
(0.08)
Strata of MTHFR combined genotypes§
    677 CC, 1298 AA29/701.001.60 (0.48-5.45)1.00 (0.30-3.27)0. 79
    677CC, 1298 AC57/1031.47 (0.48-4.50)1.76 (0.56-5.53)1.73 (0.56-5.29)0.74
    677CC, 1298 CC28/343.39 (0.92-12.50)2.24 (0.63-7.93)2.12 (0.50-8.90)0.55
    677 CC, 1298 AC/CC85/1371.88 (0.65-5.45)1.93 (0.66-5.69)1.84 (0.62-5.44)0.64
    677 CT, 1298AA43/1030.89 (0.28-2.87)1.29 (0.42-3.98)1.62 (0.50-5.25)0.50
    677CT, 1298AC49/1022.06 (0.66-6.39)1.47 (0.48-4.46)0.95 (0.28-3.19)0.26
    677 TT, 1298 AA22/430.44 (0.07-2.63)2.61 (0.71-9.67)1.83 (0.53-6.38)1.00
    677 CT/TT, 1298 AA65/1470.78 (0.25-2.44)1.60 (0.54-4.69)1.71 (0.58-5.05)0.25
Women above 55 y of age (n = 930)Cases/controlsTertiles of dietary folate equivalents*
P for trend


1 (179)
2 (240)
3 (378)
(P for interaction)
Strata of MTHFR 677C>T§
    CC141/3241.000.97 (0.58-1.64)0.90 (0.54-1.49)0.61
    CT143/2461.20 (0.72-2.00)1.34 (0.79-2.29)1.12 (0.65-1.93)0.83
    CT+TT171/2941.17 (0.72-1.92)1.21 (0.72-2.01)1.31 (0.78-2.19)0.61
(0.56)
Strata of MTHFR 1298A>C§
    AA147/2691.001.10 (0.65-1.88)1.31 (0.78-2.20)0.16
    AC136/2751.17 (0.69-1.96)1.21 (0.71-2.07)0.88 (0.51-1.52)0.32
    CC29/711.22 (0.50-2.96)0.62 (0.24-1.60)1.02 (0.46-2.29)0.67
    AC+CC165/3461.18 (0.72-1.93)1.07 (0.64-1.79)0.91 (0.55-1.52)0.20
(0.14)
Strata of MTHFR combined genotypes§
    677 CC, 1298 AA39/951.000.82 (0.30-2.22)0.77 (0.29-2.04)0.86
    677CC, 1298 AC73/1540.92 (0.38-2.22)1.28 (0.53-3.07)0.89 (0.37-2.16)0.98
    677CC, 1298 CC29/711.22 (0.42-3.55)0.59 (0.19-1.84)1.00 (0.37-2.73)0.67
    677 CC, 1298 AC/CC102/2251.00 (0.43-2.29)1.02 (0.44-2.37)0.93 (0.41-2.13)0.53
    677 CT, 1298 AA79/1240.96 (0.40-2.30)1.47 (0.61-3.59)1.42 (0.59-3.44)0.16
    677CT, 1298AC63/1211.46 (0.61-3.59)1.11 (0.45-2.76)0.81 (0.32-2.08)0.12
    677 CT/TT, 1298 AA107/1720.98 (0.43-2.26)1.20 (0.51-2.80)1.66 (0.72-3.84)0.04
  • NOTE: ORs were calculated with unconditional logistic regression and were adjusted for energy with the residual model.

  • * Tertiles of natural log of folate intake in controls, with tertile median intake (μg) in parentheses.

  • P for trend of tertiles of dietary folate equivalents (treated as a continuous variable).

  • P for interaction between tertile of folate intake (treated as a continuous variable) and occurrence of the variant allele.

  • § Model with adjustment for age, blood sampling date, method version, season, weight, height, MHT, age at menopause category, parity, household work category, socioeconomic status, smoking, total energy intake, and alcohol intake category.

  • Separate analysis of genotypes homozygous for variant alleles was not conducted because the strata included too few subjects.