The Breast Cancer Association Consortium (BCAC) has been established to conduct combined case-control analyses with augmented statistical power to try to confirm putative genetic associations with breast cancer. We genotyped nine SNPs for which there was some prior evidence of an association with breast cancer: CASP8 D302H (rs1045485), IGFBP3 -202 C --> A (rs2854744), SOD2 V16A (rs1799725), TGFB1 L10P (rs1982073), ATM S49C (rs1800054), ADH1B 3' UTR A --> G (rs1042026), CDKN1A S31R (rs1801270), ICAM5 V301I (rs1056538) and NUMA1 A794G (rs3750913). We included data from 9-15 studies, comprising 11,391-18,290 cases and 14,753-22,670 controls. We found evidence of an association with breast cancer for CASP8 D302H (with odds ratios (OR) of 0.89 (95% confidence interval (c.i.): 0.85-0.94) and 0.74 (95% c.i.: 0.62-0.87) for heterozygotes and rare homozygotes, respectively, compared with common homozygotes; P(trend) = 1.1 x 10(-7)) and weaker evidence for TGFB1 L10P (OR = 1.07 (95% c.i.: 1.02-1.13) and 1.16 (95% c.i.: 1.08-1.25), respectively; P(trend) = 2.8 x 10(-5)). These results demonstrate that common breast cancer susceptibility alleles with small effects on risk can be identified, given sufficiently powerful studies.

Objective: To examine changes in food consumption during pregnancy and the postpartum period in women of major Asian ethnic groups. Design: Using interviewer-administered questionnaires, we assessed changes in food consumption during pregnancy (26-28 weeks' gestation) and the postpartum period (3 weeks after delivery) as compared with the usual pre-pregnancy diet. Setting: Singapore. Subjects: Pregnant women (n 1027) of Chinese, Malay and Indian ethnicity (mean age 30?4 (SD 5?2) years) who participated in the Growing Up in Singapore Towards healthy Outcomes (GUSTO) study. Results: During pregnancy, participants tended to increase their consumption of milk, fruit and vegetables and decrease their consumption of tea, coffee, soft drinks and seafood (all P , 0?001). Most participants reported adherence to traditional restrictions ('confinement') during the early postpartum period (Chinese: 94?8 %, Malay: 91?6 %, Indian: 79?6 %). During the postpartum period, participants tended to increase their consumption of fish and milk-based drinks and decrease their consumption of noodles, seafood, and chocolates and sweets (all P , 0?001). Ethnic differences in food consumption were pronounced during the postpartum period. For example, most Chinese participants (87?2 %) increased their ginger consumption during the postpartum period as compared with smaller percentages of Malays (31?8 %) and Indians (40?8 %; P for ethnic difference ,0?001). Similar ethnic differences were observed for cooking wine/alcohol, herbs and spices, and herbal tea consumption. Conclusions: Marked changes in food consumption that reflect both modern dietary recommendations and the persistence of traditional beliefs were observed in Singaporean women during pregnancy and the postpartum period. Traditional beliefs should be considered in interventions to improve dietary intakes during these periods.

Nutritional data that reflect the findings from biomarkers reduce measurement error and will thus improve statistical power in studies of gene nutrient interactions in cohort studies.

We have conducted a three-stage, comprehensive single nucleotide polymorphism (SNP)-tagging association study of ESR1 gene variants (SNPs) in more than 55,000 breast cancer cases and controls from studies within the Breast Cancer Association Consortium (BCAC). No large risks or highly significant associations were revealed. SNP rs3020314, tagging a region of ESR1 intron 4, is associated with an increase in breast cancer susceptibility with a dominant mode of action in European populations. Carriers of the c-allele have an odds ratio (OR) of 1.05 [95% Confidence Intervals (CI) 1.02-1.09] relative to t-allele homozygotes, P = 0.004. There is significant heterogeneity between studies, P = 0.002. The increased risk appears largely confined to oestrogen receptor-positive tumour risk. The region tagged by SNP rs3020314 contains sequence that is more highly conserved across mammalian species than the rest of intron 4, and it may subtly alter the ratio of two mRNA splice forms.

Despite the central role of estrogen exposure in breast and endometrial cancer development and numerous studies of genes in the estrogen metabolic pathway, polymorphisms within the pathway have not been consistently associated with these cancers. We posit that this is due to the complexity of multiple weak genetic effects within the metabolic pathway that can only be effectively detected through multi-variant analysis. We conducted a comprehensive association analysis of the estrogen metabolic pathway by interrogating 239 tagSNPs within 35 genes of the pathway in three tumor samples. The discovery sample consisted of 1,596 breast cancer cases, 719 endometrial cancer cases, and 1,730 controls from Sweden; and the validation sample included 2,245 breast cancer cases and 1,287 controls from Finland. We performed admixture maximum likelihood (AML)–based global tests to evaluate the cumulative effect from multiple SNPs within the whole metabolic pathway and three sub-pathways for androgen synthesis, androgen-to-estrogen conversion, and estrogen removal. In the discovery sample, although no single polymorphism was significant after correction for multiple testing, the pathway-based AML global test suggested association with both breast (p global = 0.034) and endometrial (p global = 0.052) cancers. Further testing revealed the association to be focused on polymorphisms within the androgen-to-estrogen conversion sub-pathway, for both breast (p global = 0.008) and endometrial cancer (p global = 0.014). The sub-pathway association was validated in the Finnish sample of breast cancer (p global = 0.015). Further tumor subtype analysis demonstrated that the association of the androgen-to-estrogen conversion sub-pathway was confined to postmenopausal women with sporadic estrogen receptor positive tumors (p global = 0.0003). Gene-based AML analysis suggested CYP19A1 and UGT2B4 to be the major players within the sub-pathway. Our study indicates that the composite genetic determinants related to the androgen–estrogen conversion are important for the induction of two hormone-associated cancers, particularly for the hormone-driven breast tumour subtypes.