Table 2

Relationship between duration of breastfeeding and risk of breast cancer among BRCA1 and BRCA2 mutation carriers.

Breastfeeding duration

N

(cases/controls)

Univariate

OR (95% CI)

P

Multivariate1

OR (95% CI)

P


All subjects

1,665/1,665

Never

389/327

1.00 (reference)

1.00 (reference)

Ever

1,276/1,338

0.79 (0.67 to 0.94)

0.007

0.81 (0.68 to 0.97)

0.02

> 0 to ≤ 12 months

846/845

0.83 (0.69 to 0.99)

0.04

0.84 (0.70 to 1.02)

0.08

> 12 to ≤ 24 months

285/318

0.72 (0.58 to 0.90)

0.005

0.73 (0.58 to 0.93)

0.01

> 24 months

145/175

0.65 (0.49 to 0.86)

0.003

0.66 (0.49 to 0.89)

0.007

Per year

0.90 (0.84 to 0.97)

0.008

0.87 (0.79 to 0.95)

0.002

BRCA1

1,243/1,343

Never

267/213

1.00 (reference)

1.00 (reference)

Ever

976/1,030

0.74 (0.61 to 0.92)

0.005

0.76 (0.61 to 0.95)

0.02

> 0 to ≤ 12 months

669/658

0.79 (0.64 to 1.00)

0.03

0.81 (0.64 to 1.01)

0.06

> 12 to ≤ 24 months

212/236

0.68 (0.52 to 0.88)

0.004

0.68 (0.52 to 0.91)

0.008

> 24 months

94/136

0.50 (0.35 to 0.70)

< 0.0001

0.51 (0.35 to 0.74)

0.0003

Per year

0.84 (0.77 to 0.93)

0.0003

0.81 (0.73 to 0.91)

0.002

BRCA2

422/422

Never

122/114

1.00 (reference)

1.00 (reference)

Ever

300/308

0.91 (0.67 to 1.23)

0.53

0.90 (0.64 to 1.25)

0.51

> 0 to ≤ 12 months

177/187

0.89 (0.64 to 1.23)

0.47

0.89 (0.63 to 1.25)

0.49

> 12 to ≤ 24 months

72/82

0.84 (0.54 to 1.28)

0.40

0.83 (0.53 to 1.31)

0.43

> 24 months

51/39

1.21 (0.72 to 2.03)

0.48

1.20 (0.68 to 2.11)

0.53

Per year

1.05 (0.91 to 1.21)

0.51

1.02 (0.85 to 1.21)

0.87


1Estimate adjusted for age at menarche (continuous), age at first birth (continuous), age at first birth (continuous), alcohol consumption (ever/never) and HRT use (ever/never).

Kotsopoulos et al. Breast Cancer Research 2012 14:R42   doi:10.1186/bcr3138

Open Data