Table 5

Relative risk of aggressive breast cancer among cases in relation to plasma p,p′-DDE concentrations

Tertile 1a (<250.0)Tertile 2 (250.0–495.3<)Tertile 3 (≥495.3)
Tumor size
% tumors ≥2 cm455149
Total no. of cases9086111
OR (95% CI)b,c1.001.11 (0.52–2.04)1.18 (0.56–2.21)
Lymph-node involvement
% with invaded nodes344747
Total no. of cases797999
OR (95% CI)b,c1.001.89 (0.91–3.93)2.54 (1.20–5.35)
Lymph-node involvement and tumor size
% lymph node positive and tumors ≥2 cm203334
Total no. of cases797999
OR (95% CI)b,d1.002.33 (0.94–5.77)3.51 (1.41–8.73)
  • a p,p′-DDE concentrations are divided in tertiles according to the distribution among the 526 controls (μg/kg, lipid basis).

  • b ORs are adjusted for age, region of residence, BMI, time separating blood sampling from surgery, breast feeding duration, and number of fertile years.

  • c ORs for lymph-node involvement were adjusted for tumor size, and ORs for tumor size were adjusted for lymph-node involvement.

  • d OR of having positive nodes and a tumor ≥2 cm versus having negative nodes and a tumor <2 cm. Women with a tumor <2 cm and negative lymph-node status represent respectively 35, 31, and 34% of women in tertiles 1, 2, and 3.