Table 3.

Prenatal DES exposure in relation to risk of invasive breast cancer

Exposed
Unexposed
Age-adjusted IRR* (95% CI)Multivariable IRR (95% CI)
Person-years of follow-upCasesPerson-years of follow-upCases
Entire cohort98,5917635,046261.40 (0.89-2.22)1.40 (0.86-2.29)
Age <40 y69,2431621,98890.61 (0.27-1.38)0.57 (0.24-1.34)
Age ≥40 y29,3486013,058171.91 (1.09-3.33)2.05 (1.12-3.76)
Age 40-49 y26,4334610,843121.60 (0.85-3.02)1.62 (0.83-3.18)
Age ≥50 y2,915142,21553.00 (1.01-8.98)3.85 (1.06-14.0)
  • * IRR for breast cancer incidence in exposed women relative to unexposed.

  • Adjusted for age, years of education, number of births, age at 1st birth, age at menarche, use of female hormone supplements, use of oral contraceptives, family history of breast cancer, birthweight, and cohort.