Table 2

Risk of breast cancer (aOR) associated with the combination of the number of putative high-risk genotypes of NHEJ genes and a reproductive risk factor (years of estrogen exposure up to first full-term pregnancy), stratified by BRCA1 genotypea

Reproductive risk factor/BRCA1 Glu1038GlyaOR (95% CI)b
No. of high-risk genotypes of NHEJ genes
0–23–5
Yrs of estrogen exposure up to first full-term pregnancyc
BRCA1, Glu/Glu
 <121.00 (Ref.)0.77 (0.45–1.32)
 ≥121.06 (0.60–1.87)1.07 (0.55–2.09)
BRCA1, Glu/Gly, Gly/Gly
 <121.00 (Ref.)1.30 (0.85–1.99)
 ≥121.43 (0.92–2.22)2.55 (1.50–4.34)
  • a aOR, adjusted odds ratio; NHEJ, nonhomologous end-joining; CI, confidence interval; Ref, reference group.

  • b The aOR of breast cancer development associated with the number of putative high-risk genotypes and reproductive risk factor was estimated in a multivariate logistic regression model containing age, a family history of breast cancer, body mass index, and a group of dummy variables to represent the four different combinations of gene (number of putative high-risk genotypes) and reproductive risk factor status.

  • c For postmenopausal nulliparous women, this index was age at menopause − age at menarche, whereas, for other women, it was age at first full-term pregnancy − age at menarche.