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BACKGROUND: Breast cancer is the most common cancer and the leading cause of cancer related deaths in women worldwide. The incidence of the disease is increasing globally and this increase is occurring at a faster rate in population groups that hirtherto enjoyed low incidence. This study was designed to evaluate the role of a simple tandem repeat polymorphism (STRP) in the aromatase (CYP19) gene in breast cancer susceptibility in Nigerian women, a population of indigenous sub-Saharan African ancestry. METHODS: A case-control study recruiting 250 women with breast cancer and 250 women without the disease from four University Teaching Hospitals in Southern Nigeria was carried out between September 2002 and April 2004. Participants were recruited from the surgical outpatient clinics and surgical wards of the Nigerian institutions. A polymerase chain reaction (PCR)-based assay was employed for genotyping and product sizes were detected with an ABI 3730 DNA Analyzer. RESULTS: Conditional logistic regression analysis revealed that harboring the putative high risk genotypes conferred a 29% increased risk of breast cancer when all women in the study were considered (Odds ratio [OR] = 1.29, 95% confidence interval [CI] 0.83-2.00), although this association was not statistically significant. Subgroup analysis based on menopausal status showed similar results among premenopausal women (OR = 1.35, 95% CI 0.76-2.41 and postmenopausal women (OR = 1.27, 95% CI 0.64-2.49). The data also demonstrated marked differences in the distribution of (TTTA)n repeats in Nigerian women compared with other populations. CONCLUSION: This study has shown that harboring 10 or more repeats of the microsatellite (TTTA)n repeats of the CYY19 gene is associated with a modest increased risk of breast cancer in Nigerian women.
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BACKGROUND: Cytochrome P450 1B1 (CYP1B1) is active in the metabolism of estrogens to reactive catechols and of different procarcinogens. Several studies have investigated the relationship between genetic polymorphisms of CYP1B1 and breast cancer risk with inconsistent results. A G --> C transversion polymorphism in the heme-binding region in codon 432 of the gene results in amino acid change (Val --> Leu); the Leu allele display increased catalytic efficiency for 4-hydroxylation of estradiol in some experimental systems. METHODS: In this study, we utilized a polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) assay to assess the relationship between this polymorphism and breast cancer risk in a case control study including 250 women with breast cancer and 250 controls from four University Teaching Hospitals in Southern Nigeria. RESULTS: Heterozygosity for the CYP1B1 M1 genotype (CYP1B1 M1 [Val/Leu]) was associated with a significant 59% increased risk of breast cancer (OR = 1.59, 95% CI 1.01-2.58) while homozygosity for the genotype (CYP1B1 M1 [Leu/Leu]) conferred a non-significant 51% increased risk of breast cancer. These risk profiles were modified in subgroup analysis. In premenopausal women, harboring at least one CYP1B1 (Leu) allele conferred a significant two-fold increased risk of breast cancer (OR = 2.04, 95% CI 1.10-3.78). No significant association was observed in postmenopausal women (OR = 1.08, 95% CI 0.57-2.04). CONCLUSION: Our results suggest that the codon 432 polymorphism of the CYP1B1 gene is associated with increased risk of breast cancer and is particularly involved in breast cancer risk in premenopausal women of African descent.
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The recent upsurge in global obesity and the recognition of the role of metabolic syndrome and other correlates of obesity in the etiology of breast cancer and other chronic diseases has created the impetus for renewed interest in the role of anthropometric measures in breast cancer risk. This case-control study was designed to evaluate the role of anthropometric variables in breast cancer susceptibility in an indigenous sub-Saharan African population drawn from midwestern and southeastern Nigeria, a population grossly underreported in the global epidemiologic literature. Study participants were 250 women with breast cancer who were receiving treatment in the surgical outpatient clinics and surgical wards of four university teaching hospitals located in midwestern and southeastern Nigeria, while the controls were 250 age-matched women without breast cancer or other malignant diseases being treated for other surgical diseases in the same institutions between September 2002 and April 2004. Waist:hip ratio (WHR) was associated with a significant 2.5-fold increased risk of premenopausal breast cancer (odds ratio [OR] = 2.56, 95% confidence interval [CI] 1.48-4.41] and a 2-fold increased risk of postmenopausal breast cancer (OR = 2.00, 95% CI 1.04-2.53). Increasing height conferred a modestly nonsignificant increased risk of premenopausal breast cancer (OR = 1.59, 95% CI 0.98-2.58). The study showed that WHR is a significant predictor of breast cancer risk in Nigerian women and measures to sustain increased physical activity and ensure healthy dietary practices are recommended to reduce the burden of obesity in the population.