A three-stage genome-wide association study recently identified single nucleotide polymorphisms (SNPs) in five loci (fibroblast growth receptor 2 (FGFR2), trinucleotide repeat containing 9 (TNRC9), mitogen-activated protein kinase 3 K1 (MAP3K1), 8q24, and lymphocyte-specific protein 1 (LSP1)) associated with breast cancer risk. We investigated whether the associations between these SNPs and breast cancer risk varied by clinically important tumor characteristics in up to 23,039 invasive breast cancer cases and 26,273 controls from 20 studies. We also evaluated their influence on overall survival in 13,527 cases from 13 studies. All participants were of European or Asian origin. rs2981582 in FGFR2 was more strongly related to ER-positive (per-allele OR (95%CI) = 1.31 (1.27–1.36)) than ER-negative (1.08 (1.03–1.14)) disease (P for heterogeneity = 10−13). This SNP was also more strongly related to PR-positive, low grade and node positive tumors (P = 10−5, 10−8, 0.013, respectively). The association for rs13281615 in 8q24 was stronger for ER-positive, PR-positive, and low grade tumors (P = 0.001, 0.011 and 10−4, respectively). The differences in the associations between SNPs in FGFR2 and 8q24 and risk by ER and grade remained significant after permutation adjustment for multiple comparisons and after adjustment for other tumor characteristics. Three SNPs (rs2981582, rs3803662, and rs889312) showed weak but significant associations with ER-negative disease, the strongest association being for rs3803662 in TNRC9 (1.14 (1.09–1.21)). rs13281615 in 8q24 was associated with an improvement in survival after diagnosis (per-allele HR = 0.90 (0.83–0.97). The association was attenuated and non-significant after adjusting for known prognostic factors. Our findings show that common genetic variants influence the pathological subtype of breast cancer and provide further support for the hypothesis that ER-positive and ER-negative disease are biologically distinct. Understanding the etiologic heterogeneity of breast cancer may ultimately result in improvements in prevention, early detection, and treatment.

Various studies suggest that vitamin D may reduce breast cancer risk. Most studies assessed the effects of dietary intake only, although endogenous production is an important source of vitamin D. Therefore, the measurement of serum 25-hydroxyvitamin D [25(OH)D] better indicates overall vitamin D status. To assess the association of 25(OH)D serum concentrations with post-menopausal breast cancer risk, we used a population-based case-control study in Germany, which recruited incident breast cancer patients aged 50-74 between 2002 and 2005. Information on sociodemographic and breast cancer risk factors was collected by personal interview. For this analysis, we included 1394 cases and 1365 controls, matched on year of birth and time of blood collection. Conditional logistic regression was used to calculate odds ratios (ORs) for breast cancer adjusted for potential confounders. Serum 25(OH)D concentration was significantly inversely associated with post-menopausal breast cancer risk. Compared with the lowest category (<30 nM), OR [95% confidence intervals (CI)] for the higher categories of 25(OH)D (30-45, 45-60, 60-75 and >/=75 nM) were 0.57 (0.45-0.73), 0.49 (0.38-0.64), 0.43 (0.32-0.57) and 0.31 (0.24-0.42), respectively (P(trend) < 0.0001). Analysis using fractional polynomials indicated a non-linear association. The association was stronger in women never using menopausal hormone therapy (HT) compared with past and current users (P(interaction) < 0.0001). Our findings strongly suggest a protective effect for post-menopausal breast cancer through a better vitamin D supply as characterized by serum 25(OH)D measurement, with a stronger inverse association in women with low serum 25(OH)D concentrations (<50 nM).

In a large population-based case-control study in Germany, including 3,464 breast cancer cases aged 50-74 at diagnosis and 6,657 population based and frequency matched controls, we investigated the effects of menopausal hormone therapy (HT) by type, regimen, timing and progestagenic constituent on postmenopausal breast cancer risk overall and according to histological type. Data were collected by face-to-face interviews. Logistic and polytomous logistic regression analysis were used to estimate odds ratios (OR) and 95%-confidence intervals (95% CI). Risk of invasive breast cancer was significantly elevated in current users (OR, 1.73, 95% CI, 1.55-1.94) and heterogeneous by histological type (p < 0.01), being more than 2-fold higher for lobular and tubular than for ductal cancer. Risks for current users varied significantly by type and regimen of HT, with ORs per year of use of 1.05 (95% CI, 1.04-1.06) for continuous combined estrogen-progestagen, 1.03 (95% CI, 1.02-1.04) for cyclical EP and 1.01 (95% CI, 1.00-1.03) for estrogen-only therapy. No statistically significant increase in risk was observed after 5 years of cessation of HT use for any histological type. Analyses of progestagenic content by regimen revealed a significantly higher risk for continuously administered norethisterone-or levonorgestrel-derived progestagens than for continuously administered progesterone-derived progestagens (OR, 2.27, 95% CI, 1.98-2.62 vs. 1.47, 95% CI, 1.12-1.93, respectively, p 5 0.003), which may be explained by dose rather than type of progestagen. These data suggest that the risks associated with menopausal HT differ by type and regimen of HT and histological type of breast cancer and may vary by progestagenic component, depending on the effective dose. ' 2008 Wiley-Liss, Inc.Key words: breast cancer; histological type; hormone therapy; progestin; epidemiology Menopausal hormone therapy (HT) has been established as a risk factor for the development of breast cancer, 1 with combined estrogen-progestagen (EP) therapy posing a greater risk than mono-estrogen therapy.2-7 The extent to which this risk difference is in turn affected by duration and recency of use, particularly for past long-term users, requires further clarification. Recent evidence from observational studies has shown that risk varies according to tumor histology, with current use of both mono-estrogen and EP therapy carrying greater risks for invasive lobular and tubular cancers than for invasive ductal cancer. 4,[8][9][10][11][12][13][14][15][16] The higher risk associated with EP therapy compared to mono-estrogen therapy has also been observed across different histological tumor types. 6,17,18 Several studies have investigated differences in risk by regimen, 2,5,18-21 however, a higher risk for continuous than for cyclical EP therapy was found only in Scandinavian studies. 18,20,22 Less information is available on the role of progestagens in EP therapy, specifically regarding the effects of type, dose and the number of days it is administered each month. Wh...