Risk of breast cancer by CYP1A1-exon7 polymorphism and plasma levels of lipid-adjusted PCBs among all women and postmenopausal women only
| CYP1A1 genotype . | Tertile PCBsa (cut-offs μg/g) . | Cases . | Controls . | RR (95% CI) . | Multivariate RRb (95% CI) . | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Postmenopausal women (293 case/control pairs) | ||||||||||
| WT/WT | 1 (0.13–0.47) | 84 | 81 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.47–0.67) | 82 | 87 | 0.91 (0.59–1.42) | 1.00 (0.63–1.60) | |||||
| WT/WT | 3 (0.67–1.99) | 84 | 90 | 0.90 (0.55–1.48) | 0.97 (0.57–1.67) | |||||
| Variantsc | 1 (0.13–0.47) | 9 | 16 | 0.53 (0.21–1.31) | 0.52 (0.20–1.36) | |||||
| Variants | 2 (0.47–0.67) | 15 | 12 | 1.19 (0.51–2.78) | 1.29 (0.51–3.21) | |||||
| Variants | 3 (0.67–1.99) | 19 | 7 | 2.76 (1.04–7.35) | 2.78 (0.99–7.82) | |||||
| Test for interactiond | 0.03 | 0.05 | ||||||||
| All women (367 case/control pairs) | ||||||||||
| WT/WT | 1 (0.13–0.46) | 113 | 101 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.46–0.65) | 100 | 103 | 0.86 (0.58–1.28) | 0.93 (0.60–1.43) | |||||
| WT/WT | 3 (0.65–1.99) | 103 | 107 | 0.84 (0.54–1.32) | 0.89 (0.55–1.45) | |||||
| Variantsb | 1 (0.13–0.46) | 12 | 21 | 0.49 (0.23–1.07) | 0.54 (0.24–1.22) | |||||
| Variants | 2 (0.46–0.65) | 18 | 21 | 0.72 (0.36–1.46) | 0.76 (0.35–1.63) | |||||
| Variants | 3 (0.65–1.99) | 21 | 14 | 1.33 (0.62–2.83) | 1.36 (0.60–3.12) | |||||
| Test for interaction | 0.10 | 0.19 | ||||||||
| CYP1A1 genotype . | Tertile PCBsa (cut-offs μg/g) . | Cases . | Controls . | RR (95% CI) . | Multivariate RRb (95% CI) . | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Postmenopausal women (293 case/control pairs) | ||||||||||
| WT/WT | 1 (0.13–0.47) | 84 | 81 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.47–0.67) | 82 | 87 | 0.91 (0.59–1.42) | 1.00 (0.63–1.60) | |||||
| WT/WT | 3 (0.67–1.99) | 84 | 90 | 0.90 (0.55–1.48) | 0.97 (0.57–1.67) | |||||
| Variantsc | 1 (0.13–0.47) | 9 | 16 | 0.53 (0.21–1.31) | 0.52 (0.20–1.36) | |||||
| Variants | 2 (0.47–0.67) | 15 | 12 | 1.19 (0.51–2.78) | 1.29 (0.51–3.21) | |||||
| Variants | 3 (0.67–1.99) | 19 | 7 | 2.76 (1.04–7.35) | 2.78 (0.99–7.82) | |||||
| Test for interactiond | 0.03 | 0.05 | ||||||||
| All women (367 case/control pairs) | ||||||||||
| WT/WT | 1 (0.13–0.46) | 113 | 101 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.46–0.65) | 100 | 103 | 0.86 (0.58–1.28) | 0.93 (0.60–1.43) | |||||
| WT/WT | 3 (0.65–1.99) | 103 | 107 | 0.84 (0.54–1.32) | 0.89 (0.55–1.45) | |||||
| Variantsb | 1 (0.13–0.46) | 12 | 21 | 0.49 (0.23–1.07) | 0.54 (0.24–1.22) | |||||
| Variants | 2 (0.46–0.65) | 18 | 21 | 0.72 (0.36–1.46) | 0.76 (0.35–1.63) | |||||
| Variants | 3 (0.65–1.99) | 21 | 14 | 1.33 (0.62–2.83) | 1.36 (0.60–3.12) | |||||
| Test for interaction | 0.10 | 0.19 | ||||||||
Cut-offs for tertiles based on the appropriate control distribution, all women or postmenopausal only depending on the analysis.
RR adjusted for history of breast cancer in mother or a sister, a history of benign breast disease, age at menarche (<12 years, 12 years, >12 years), body mass index (<25, 25–29, 30+ kg/m2), number of children, and age at birth of first child (nulliparous, 1–2 children and age ≤24 at first birth, 1–2 children and age >24 at first birth, ≥3 children and age ≤24 at first birth, and ≥3 children and age >24 at first birth), and duration of lactation (0, 1–6 months, and >6 months).
Variants are all women who are either heterozygous or homozygous for the variant allele.
Test for interaction, likelihood ratio test comparing model with cross-classified variables with model with main effects only.