Risk of breast cancer by CYP1A1-MspI 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) | 79 | 78 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.47–0.67) | 73 | 79 | 0.94 (0.61–1.46) | 1.00 (0.62–1.60) | |||||
| WT/WT | 3 (0.67–1.99) | 85 | 82 | 1.08 (0.67–1.75) | 1.18 (0.69–2.01) | |||||
| Variantsc | 1 (0.13–0.47) | 14 | 19 | 0.70 (0.32–1.54) | 0.53 (0.27–1.23) | |||||
| Variants | 2 (0.47–0.67) | 24 | 20 | 1.22 (0.63–2.38) | 1.37 (0.67–2.79) | |||||
| Variants | 3 (0.67–1.99) | 18 | 15 | 1.27 (0.59–2.76) | 1.08 (0.47–2.48) | |||||
| Test for interactiond | 0.47 | 0.22 | ||||||||
| All women (367 case/control pairs) | ||||||||||
| WT/WT | 1 (0.13–0.46) | 106 | 97 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.46–0.65) | 86 | 99 | 0.81 (0.54–1.21) | 0.84 (0.54–1.30) | |||||
| WT/WT | 3 (0.65–1.99) | 102 | 103 | 0.93 (0.60–1.45) | 1.00 (0.62–1.63) | |||||
| Variantsb | 1 (0.13–0.46) | 19 | 25 | 0.70 (0.36–1.35) | 0.63 (0.31–1.28) | |||||
| Variants | 2 (0.46–0.65) | 32 | 25 | 1.16 (0.65–2.09) | 1.24 (0.66–2.33) | |||||
| Variants | 3 (0.65–1.99) | 22 | 18 | 1.16 (0.58–2.34) | 0.94 (0.44–2.01) | |||||
| Test for interaction | 0.24 | 0.21 | ||||||||
| 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) | 79 | 78 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.47–0.67) | 73 | 79 | 0.94 (0.61–1.46) | 1.00 (0.62–1.60) | |||||
| WT/WT | 3 (0.67–1.99) | 85 | 82 | 1.08 (0.67–1.75) | 1.18 (0.69–2.01) | |||||
| Variantsc | 1 (0.13–0.47) | 14 | 19 | 0.70 (0.32–1.54) | 0.53 (0.27–1.23) | |||||
| Variants | 2 (0.47–0.67) | 24 | 20 | 1.22 (0.63–2.38) | 1.37 (0.67–2.79) | |||||
| Variants | 3 (0.67–1.99) | 18 | 15 | 1.27 (0.59–2.76) | 1.08 (0.47–2.48) | |||||
| Test for interactiond | 0.47 | 0.22 | ||||||||
| All women (367 case/control pairs) | ||||||||||
| WT/WT | 1 (0.13–0.46) | 106 | 97 | 1.00 | 1.00 | |||||
| WT/WT | 2 (0.46–0.65) | 86 | 99 | 0.81 (0.54–1.21) | 0.84 (0.54–1.30) | |||||
| WT/WT | 3 (0.65–1.99) | 102 | 103 | 0.93 (0.60–1.45) | 1.00 (0.62–1.63) | |||||
| Variantsb | 1 (0.13–0.46) | 19 | 25 | 0.70 (0.36–1.35) | 0.63 (0.31–1.28) | |||||
| Variants | 2 (0.46–0.65) | 32 | 25 | 1.16 (0.65–2.09) | 1.24 (0.66–2.33) | |||||
| Variants | 3 (0.65–1.99) | 22 | 18 | 1.16 (0.58–2.34) | 0.94 (0.44–2.01) | |||||
| Test for interaction | 0.24 | 0.21 | ||||||||
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.