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Title: CYP17 promoter polymorphism and breast cancer in Australian women under age forty years
Authors: Spurdle AB; Easton DF; Chenevix-Trench G; Hopper JL; Dite GS; Chen X; Cui J; McCredie MR; Giles GG; Southey MC; Venter DJ
Categories: Etiology - Endogenous Factors in the Origin and Cause of Cancer
Cancer Type - Breast Cancer
Keywords: Adult; cancer; Case-Control Studies; diagnosis; DNA Primers; DNA,Neoplasm; enzymology; Family; Female; Genes,Brca1; Genes,Tumor Suppressor; Age Factors; genetics; Genotype; history; Humans; Logistic Models; methods; Mutation; Polymerase Chain Reaction; Polymorphism,Genetic; Promoter Regions (Genetics); Age of Onset; Research; Research Support,Non-U.S.Gov't; Risk; Risk Factors; Steroid 17-alpha-Hydroxylase; Women; Alleles; analysis; Australia; biosynthesis; breast; Breast Neoplasms
Year: 2000
Journal Title: Journal of the National Cancer Institute
Volume: 92
Issue: 20
Page number start: 1674
Page number end: 1681
Abstract: BACKGROUND: The cytochrome P450c17alpha enzyme functions in the steroid biosynthesis pathway, and altered endogenous steroid hormone levels have been reported to be associated with a T to C polymorphism in the 5' promoter region of the CYP17 gene. Because steroid hormone exposure is known to influence breast cancer risk, we conducted a population-based, case-control-family study to assess the relationship between the CYP17 promoter polymorphism and early-onset breast cancer. METHODS: Case subjects under 40 years of age at diagnosis of a first primary breast cancer, population-sampled control subjects, and the relatives of both case and control subjects were interviewed to record family history of breast cancer and other risk factors. CYP17 genotype was determined in 369 case subjects, 284 control subjects, and 91 relatives of case subjects. Genotype distributions were compared by logistic regression, and cumulative risk was estimated by a modified segregation analysis. All statistical tests were two-tailed. RESULTS: Compared with the TT genotype (i.e., individuals homozygous for the T allele), the TC genotype was not associated with increased breast cancer risk (P: =.7). Compared with the TT and TC genotypes combined, the CC genotype was associated with a relative risk of 1. 81 (95% confidence interval [CI] = 1.15-2.86; P: =.01) before adjustment for measured risk factors and 1.63 (95% CI = 1.00-2.64; P: =.05) after adjustment. There was an excess of CC genotypes in case subjects who had at least one affected first- or second-degree relative, compared with control subjects unstratified by family history of breast cancer (23% versus 11%; P: =.006), and these case subjects had a threefold to fourfold higher risk than women of other groups defined by genotype and family history of breast cancer. Analysis of breast cancer in first- and second-degree relatives of case subjects with the CC genotype, excluding two known carriers of a deleterious mutation in BRCA1 or BRCA2, gave a relative hazard in women with the CC genotype of 3.48 (95% CI = 1.13-10.74; P: =.04), which is equivalent to a cumulative risk of 16% to age 70 years. CONCLUSIONS: The CC genotype may modify the effect of other familial risk factors for early-onset breast cancer
Programme: Cancer Causes
Division: Cancer Research Division
Appears in Collections:Research Articles

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