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Polymorphisms in CYP1A1 and breast carcinoma risk in a population-based case–control study of Chinese women
Article first published online: 26 APR 2005
Copyright © 2005 American Cancer Society
Volume 103, Issue 11, pages 2228–2235, 1 June 2005
How to Cite
Boyapati, S. M., Shu, X. O., Gao, Y.-T., Cai, Q., Jin, F. and Zheng, W. (2005), Polymorphisms in CYP1A1 and breast carcinoma risk in a population-based case–control study of Chinese women. Cancer, 103: 2228–2235. doi: 10.1002/cncr.21056
- Issue published online: 18 MAY 2005
- Article first published online: 26 APR 2005
- Manuscript Accepted: 25 JAN 2005
- Manuscript Revised: 31 DEC 2004
- Manuscript Received: 20 MAY 2004
- National Cancer Institute. Grant Numbers: RO1CA64277, RO1CA90899
- polymorphism (genetics);
- breast carcinoma;
- estrogen exposure;
- case–control study
Cytochrome P450 1A1 (CYP1A1) is involved in the 2-hydroxylation of estrogen, the hormone that plays a critical role in the etiology of breast carcinoma.
The authors evaluated common polymorphisms in the CYP1A1 gene in relation to breast carcinoma risk in a large population-based case–control study among Chinese women, the Shanghai Breast Cancer Study. Because the CYP1A1*3 and CYP1A1*4 alleles were not detected in the study population, analyses were performed for CYP1A1*2A (TC transition in the 3′ noncoding region) and CYP1A1*2C (AG transition in exon 7, resulting in a substitution of Val for Ile) in 1134 patients with breast carcinoma and 1227 controls.
The frequencies of the variant allele were 38.3% and 38.8% among cases and controls (P = 0.91), respectively, for the CYP1A1*2A polymorphism, and 23.1% and 24.8% (P = 0.26) for the CYP1A1*2C polymorphism. Homozygosity for both variant alleles in these 2 polymorphic sites (CYP1A1*2B) was associated with a borderline significant odds ratio (OR) of 0.71 (95% confidence interval [CI], 0.47–1.06). The reduced risk was more pronounced among postmenopausal women with long duration (> 30 yrs) of menstruation (OR = 0.43; 95% CI, 0.19–0.99) or among women with a low waist-to-hip ratio (OR = 0.52; 95% CI, 0.28–0.94).
Results from the current study suggest that homozygosity for the CYP1A1*2A and CYP1A1*2C alleles in the CYP1A1 gene may be associated with a reduced risk for breast carcinoma, particularly among lean women with long-term endogenous estrogen exposure. Cancer 2005. © 2005 American Cancer Society.