Table 2

Breast cancer incidence rate ratios (IRRs) in relation to SRD5A2 V89L genotype

GenotypeNo. of breast cancer cases (%)No. of women in subcohort (%)IRR unadjusted (95% CI)IRR adjusted (95% CI)a
Val/Val 140 (47)198 (52)11
Val/Leu 137 (46)153 (40)1.3 (1.0–1.9)1.5 (1.0–2.2)
Leu/Leu 18 (6)31 (8)0.8 (0.5–1.3)1.1 (0.5–2.1)
Total295 (100)382 (100)
Allele frequency (95% CI)b
Val70.7% (65.5–75.8)71.9% (67.4–76.4)
Leu29.3% (24.1–34.5)28.1% (23.6–32.6)
  • a Adjusted for: age at recruitment, height, weight, smoking (ever/never), parity/age at first full-term pregnancy (nulliparous/≤25 years/26–29 years/≥30 years), oral contraceptive use (ever/never), age at menopause, family history of breast cancer, and regular HRT use in past 12 months (yes/no).

  • b Hardy-Weinberg equilibrium was tested in the subcohort by a goodness-of-fit χ2 test with df = 1: P = 0.84.