Prospective associations of vitamin D with β-cell function and glycemia: the PROspective Metabolism and ISlet cell Evaluation (PROMISE) cohort study

OBJECTIVE

To examine the prospective associations of baseline vitamin D [25-hydroxyvitamin D; 25(OH)D] with insulin resistance (IR), β-cell function, and glucose homeostasis in subjects at risk for type 2 diabetes.

RESEARCH DESIGN AND METHODS

We followed 489 subjects, aged 50 ± 10 years, for 3 years. At baseline and follow-up, 75-g oral glucose tolerance tests (OGTTs) were administered. IR was measured using the Matsuda index (IS(OGTT)) and the homeostasis model assessment of IR (HOMA-IR), β-cell function was determined using both the insulinogenic index divided by HOMA-IR (IGI/IR) and the insulin secretion sensitivity index-2 (ISSI-2), and glycemia was assessed using the area under the glucose curve (AUC(glucose)). Regression models were adjusted for age, sex, ethnicity, season, and baseline value of the outcome variable, as well as baseline and change in physical activity, vitamin D supplement use, and BMI.

RESULTS

Multivariate linear regression analyses indicated no significant association of baseline 25(OH)D with follow-up IS(OGTT) or HOMA-IR. There were, however, significant positive associations of baseline 25(OH)D with follow-up IGI/IR (β = 0.005, P = 0.015) and ISSI-2 (β = 0.002, P = 0.023) and a significant inverse association of baseline 25(OH)D with follow-up AUC(glucose) (β = -0.001, P = 0.007). Progression to dysglycemia (impaired fasting glucose, impaired glucose tolerance, or type 2 diabetes) occurred in 116 subjects. Logistic regression analyses indicated a significant reduced risk of progression with higher baseline 25(OH)D (adjusted odds ratio 0.69 [95% CI 0.53-0.89]), but this association was not significant after additional adjustment for baseline and change in BMI (0.78 [0.59-1.02]).

CONCLUSIONS

Higher baseline 25(OH)D independently predicted better β-cell function and lower AUC(glucose) at follow-up, supporting a potential role for vitamin D in type 2 diabetes etiology.

Breast cancer risk for noncarriers of family-specific BRCA1 and BRCA2 mutations: findings from the Breast Cancer Family Registry

PURPOSE

Women with germline BRCA1 and BRCA2 mutations have five- to 20-fold increased risks of developing breast and ovarian cancer. A recent study claimed that women testing negative for their family-specific BRCA1 or BRCA2 mutation (noncarriers) have a five-fold increased risk of breast cancer. We estimated breast cancer risks for noncarriers by using a population-based sample of patients with breast cancer and their female first-degree relatives (FDRs).

PATIENTS AND METHODS

Patients were women with breast cancer and their FDRs enrolled in the population-based component of the Breast Cancer Family Registry; patients with breast cancer were tested for BRCA1 and BRCA2 mutations, as were FDRs of identified mutation carriers. We used segregation analysis to fit a model that accommodates familial correlation in breast cancer risk due to unobserved shared risk factors.

RESULTS

We studied 3,047 families; 160 had BRCA1 and 132 had BRCA2 mutations. There was no evidence of increased breast cancer risk for noncarriers of identified mutations compared with FDRs from families without BRCA1 or BRCA2 mutations: relative risk was 0.39 (95% CI, 0.04 to 3.81). Residual breast cancer correlation within families was strong, suggesting substantial risk heterogeneity in women without BRCA1 or BRCA2 mutations, with some 3.4% of them accounting for roughly one third of breast cancer cases.

CONCLUSION

These results support the practice of advising noncarriers that they do not have any increase in breast cancer risk attributable to the family-specific BRCA1 or BRCA2 mutation.

Abstract B54: Reproductive status at first diagnosis influences risk of radiation-induced second primary contralateral breast cancer in The WECARE Study

The breast undergoes changes in composition, function and hormonal milieu during puberty, pregnancy, lactation and postmenopausal involution. These changes may influence the susceptibility of the breast to carcinogens, including exposure to ionizing radiation.

The Women's Environmental, Cancer and Radiation Epidemiology (WECARE) Study is a multi-center, population-based, case-control study of 708 women (cases) with asynchronous contralateral breast cancer (CBC) and 1,399 women (controls) with unilateral breast cancer (UBC). Radiation therapy (RT) records were used to reconstruct the radiation dose to the location in the contralateral breast where the second cancer arose (or to the equivalent breast location for UBC controls). Rate ratios (RR) and 95% confidence intervals (CI) were computed to assess the relationship between reproductive status at first breast cancer diagnosis, RT and risk of CBC, adjusting for known breast cancer risk factors: age at (first) diagnosis, menopausal status/age at menopause at first diagnosis, age at menarche, number of full-term pregnancies, first degree family history of breast cancer, histology and stage of first primary breast cancer, and treatment (chemotherapy/hormonal therapy).

Women who were nulliparous at first diagnosis and exposed to ≥1 gray (Gy) to the contralateral breast, had a higher risk of CBC than unexposed nulliparous women (RR=2.2, 95% CI 1.2–4.0). An increased risk was not seen in RT exposed parous women (RR=1.1, 95% CI 0.8–1.4). Women treated with RT who later became pregnant had a greater risk of CBC compared with unexposed women who also became pregnant (RR=6.0, 95% CI 1.3, 28.4), though these results were based on small numbers. The effect of radiation on risk of CBC did not vary by number of pregnancies, history of breast feeding or menopausal status at the time of first breast cancer diagnosis.

These results suggest that RT may be associated with an increased risk of developing a second breast cancer in nulliparous but not parous women.

Women who become pregnant after first breast cancer diagnosis may also be at an increased risk of CBC. It is possible that RT could be the initiating event, leading to preneoplastic cellular changes that are then promoted by the hormonal changes of a subsequent pregnancy.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):B54.

Confirmation of 5p12 as a susceptibility locus for progesterone-receptor-positive, lower grade breast cancer

BACKGROUND

The single-nucleotide polymorphism (SNP) 5p12-rs10941679 has been found to be associated with risk of breast cancer, particularly estrogen receptor (ER)-positive disease. We aimed to further explore this association overall, and by tumor histopathology, in the Breast Cancer Association Consortium.

METHODS

Data were combined from 37 studies, including 40,972 invasive cases, 1,398 cases of ductal carcinoma in situ (DCIS), and 46,334 controls, all of white European ancestry, as well as 3,007 invasive cases and 2,337 controls of Asian ancestry. Associations overall and by tumor invasiveness and histopathology were assessed using logistic regression.

RESULTS

For white Europeans, the per-allele OR associated with 5p12-rs10941679 was 1.11 (95% CI = 1.08-1.14, P = 7 × 10(-18)) for invasive breast cancer and 1.10 (95% CI = 1.01-1.21, P = 0.03) for DCIS. For Asian women, the estimated OR for invasive disease was similar (OR = 1.07, 95%CI = 0.99-1.15, P = 0.09). Further analyses suggested that the association in white Europeans was largely limited to progesterone receptor (PR)-positive disease (per-allele OR = 1.16, 95% CI = 1.12-1.20, P = 1 × 10(-18) vs. OR = 1.03, 95% CI = 0.99-1.07, P = 0.2 for PR-negative disease; P(heterogeneity) = 2 × 10(-7)); heterogeneity by ER status was not observed (P = 0.2) once PR status was accounted for. The association was also stronger for lower grade tumors [per-allele OR (95% CI) = 1.20 (1.14-1.25), 1.13 (1.09-1.16), and 1.04 (0.99-1.08) for grade 1, 2, and 3/4, respectively; P(trend) = 5 × 10(-7)].

CONCLUSION

5p12 is a breast cancer susceptibility locus for PR-positive, lower grade breast cancer.

IMPACT

Multicenter fine-mapping studies of this region are needed as a first step to identifying the causal variant or variants.

Identification of germline alterations of the mad homology 2 domain of SMAD3 and SMAD4 from the Ontario site of the breast cancer family registry (CFR)

INTRODUCTION

A common feature of neoplastic cells is that mutations in SMADs can contribute to the loss of sensitivity to the anti-tumor effects of transforming growth factor-β (TGF-β). However, germline mutation analysis of SMAD3 and SMAD4, the principle substrates of the TGF-β signaling pathway, has not yet been conducted in breast cancer. Thus, it is currently unknown whether germline SMAD3 and SMAD4 mutations are involved in breast cancer predisposition.

METHODS

We performed mutation analysis of the highly conserved mad-homology 2 (MH2) domains for both genes in genomic DNA from 408 non-BRCA1/BRCA2 breast cancer cases and 710 population controls recruited by the Ontario site of the breast cancer family registry (CFR) using denaturing high-performance liquid chromatography (DHPLC) and direct DNA sequencing. The results were interpreted in several ways. First, we adapted nucleotide diversity analysis to quantitatively assess whether the frequency of alterations differ between the two genes. Next, in silico tools were used to predict variants' effect on domain function and mRNA splicing. Finally, 37 cases or controls harboring alterations were tested for aberrant splicing using reverse-transcription polymerase chain reaction (PCR) and real-time PCR statistical comparison of germline expressions by non-parametric Mann-Whitney test of independent samples.

RESULTS

We identified 27 variants including 2 novel SMAD4 coding variants c.1350G > A (p.Gln450Gln), and c.1701A > G (p.Ile525Val). There were no inactivating mutations even though c.1350G > A was predicted to affect exonic splicing enhancers. However, several additional findings were of note: 1) nucleotide diversity estimate for SMAD3 but not SMAD4 indicated that coding variants of the MH2 domain were more infrequent than expected; 2) in breast cancer cases SMAD3 was significantly over-expressed relative to controls (P < 0.05) while the case harboring SMAD4 c.1350G > A was associated with elevated germline expression (> 5-fold); 3) separate analysis using tissue expression data showed statistically significant over-expression of SMAD3 and SMAD4 in breast carcinomas.

CONCLUSIONS

This study shows that inactivating germline alterations in SMAD3 and SMAD4 are rare, suggesting a limited role in driving tumorigenesis. Nevertheless, aberrant germline expressions of SMAD3 and SMAD4 may be more common in breast cancer than previously suspected and offer novel insight into their roles in predisposition and/or progression of breast cancer.

Ultraviolet sunlight exposure during adolescence and adulthood and breast cancer risk: a population-based case-control study among Ontario women

Recent studies suggest that vitamin D may be associated with reduced breast cancer risk, but most studies have evaluated only dietary vitamin D intake. The associations among ultraviolet radiation from sunlight, factors related to cutaneous vitamin D production, and breast cancer risk were evaluated in a population-based case-control study conducted in Ontario, Canada, between 2003 and 2004 (n = 3,101 cases and n = 3,471 controls). Time spent outdoors was associated with reduced breast cancer risk during 4 periods of life (>21 vs. ≤6 hours/week age-adjusted odds ratio (OR) = 0.71, 95% confidence interval (CI): 0.60, 0.85 in the teenage years; OR = 0.64, 95% CI: 0.53, 0.76 in the 20s-30s; OR = 0.74, 95% CI: 0.61, 0.88 in the 40s-50s; and OR = 0.50, 95% CI: 0.37, 0.66 in the 60s-74 years). Sun protection practices and ultraviolet radiation were not associated with breast cancer risk. A combined solar vitamin D score, including all the variables related to vitamin D production, was significantly associated with reduced breast cancer risk. These associations were not confounded or modified by menopausal status, dietary vitamin D intake, or physical activity. This study suggests that factors suggestive of increased cutaneous production of vitamin D are associated with reduced breast cancer risk.

The potential value of sibling controls compared with population controls for association studies of lifestyle-related risk factors: an example from the Breast Cancer Family Registry

BACKGROUND

A previous Australian population-based breast cancer case-control study found indirect evidence that control participation, although high, was not random. We hypothesized that unaffected sisters may provide a more appropriate comparison group than unrelated population controls.

METHODS

Three population-based case-control-family studies of breast cancer in women of white European origin were carried out by the Australian, Ontario and Northern California sites of the Breast Cancer Family Registry. We compared risk factors between 3643 cases, 2444 of their unaffected sisters and 2877 population controls and conducted separate case-control analyses based on population and sister controls using unconditional multivariable logistic regression.

RESULTS

Compared with sister controls, population controls were more highly educated, had an earlier age at menarche, fewer births, their first birth at a later age and their last birth more recently. The established breast cancer associations detected using sister controls, but not detected using population controls, were decreasing risk with each of later age at menarche, more births, younger age at first birth and greater time since last birth.

CONCLUSIONS

Since participation of population controls might be unintentionally related to some risk factors, we hypothesize that sister controls could provide more valid relative risk estimates and be recruited at lower cost. Given declining study participation by population controls, this contention is highly relevant to epidemiologic research.

Promoter methylation of Wnt5a is associated with microsatellite instability and BRAF V600E mutation in two large populations of colorectal cancer patients

Background:

In colorectal cancer (CRC), tumour microsatellite instability (MSI) status and CpG island methylator phenotype (CIMP) status are indicators of patient outcome, but the molecular events that give rise to these outcomes remain largely unknown. Wnt5a is a critical regulator of non-canonical Wnt activity and promoter hypermethylation of this gene has emerging prognostic roles in CRC; however the frequency and prognostic significance of this epigenetic event have not been explored in the context of colorectal tumour subtype. Consequently, we investigated the frequency and prognostic significance of Wnt5a methylation in a large cohort of MSI-stratified CRCs.

Methods:

Methylation was quantified in a large cohort of 1232 colorectal carcinomas from two clinically distinct populations from Canada. Associations were examined between methylation status and clinicopathlogical features, including tumour MSI status, BRAF V600E mutation, and patient survival.

Results:

In Ontario, Wnt5a methylation was strongly associated with MSI tumours after adjustment for age, sex, and tumour location (odds ratio (OR)=4.2, 95% confidence interval (CI)=2.4–7.4, P<10⁻⁶) and with BRAF V600E mutation, a marker of CIMP (OR=12.3, 95% CI=6.9–21.7, P<10⁻¹⁷), but was not associated with patient survival. Concordant results were obtained in Newfoundland.

Conclusion:

Methylation of Wnt5a is associated with distinct tumour subtypes, strengthening the evidence of an epigenetic-mediated Wnt bias in CRC.

Promoter methylation of Wnt antagonists DKK1 and SFRP1 is associated with opposing tumor subtypes in two large populations of colorectal cancer patients

Aberrant activation of canonical Wnt signaling is a hallmark event in colorectal carcinogenesis. The Dickkopf-1 (DKK1) and Secreted Frizzled Related Protein 1 (SFRP1) genes encode extracellular inhibitors of Wnt signaling that are frequently silenced by promoter hypermethylation in colorectal cancer (CRC). These methylation events have been identified as prognostic markers of patient outcome and tumor subtype in several cancers but similar roles in CRC have not been comprehensively examined. In CRC, the microsatellite instability (MSI) subtype associates with favorable disease outcome but the molecular events that are responsible remain poorly understood. Consequently, we quantified promoter methylation status of the Wnt antagonist genes DKK1 and SFRP1 in a large population-based cohort of CRCs from Ontario (n = 549) and Newfoundland (n = 696) stratified by MSI status. We examined the association between methylation status and clinicopathological features including tumor MSI status and patient survival. DKK1 and SFRP1 were methylated in 13 and 95% of CRCs, respectively. In Ontario, DKK1 methylation was strongly associated with MSI tumors after adjustment for age, sex and tumor location [odds ratio (OR) = 13.7, 95% confidence interval (CI) = 7.8-24.2, P < 0.001]. Conversely, SFRP1 methylation was inversely associated with MSI tumors after these adjustments (OR = 0.3, 95% CI = 0.1-0.9, P = 0.009). Similar results were obtained in Newfoundland. There were no independent associations with recurrence-free survival. This is the first large study to identify associations between Wnt antagonist promoter hypermethylation and CRC MSI subtype. These events provide insight into subtype-specific epigenetic mediation of Wnt signaling in CRC.

Associations of breast cancer risk factors with tumor subtypes: a pooled analysis from the Breast Cancer Association Consortium studies

BACKGROUND

Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors.

METHODS

We pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided.

RESULTS

In case-case analyses, of the epidemiological risk factors examined, early age at menarche (≤12 years) was less frequent in case patients with PR(-) than PR(+) tumors (P = .001). Nulliparity (P = 3 × 10(-6)) and increasing age at first birth (P = 2 × 10(-9)) were less frequent in ER(-) than in ER(+) tumors. Obesity (body mass index [BMI] ≥ 30 kg/m(2)) in younger women (≤50 years) was more frequent in ER(-)/PR(-) than in ER(+)/PR(+) tumors (P = 1 × 10(-7)), whereas obesity in older women (>50 years) was less frequent in PR(-) than in PR(+) tumors (P = 6 × 10(-4)). The triple-negative (ER(-)/PR(-)/HER2(-)) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/or epidermal growth factor receptor [EGFR](+)) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER(+) or PR(+) tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors.

CONCLUSIONS

This study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology.

Germline mutations in CDH1 are infrequent in women with early-onset or familial lobular breast cancers

BACKGROUND

Germline mutations in CDH1 are associated with hereditary diffuse gastric cancer; lobular breast cancer also occurs excessively in families with such condition.

METHOD

To determine if CDH1 is a susceptibility gene for lobular breast cancer in women without a family history of diffuse gastric cancer, germline DNA was analysed for the presence of CDH1 mutations in 318 women with lobular breast cancer who were diagnosed before the age of 45 years or had a family history of breast cancer and were not known, or known not, to be carriers of germline mutations in BRCA1 or BRCA2. Cases were ascertained through breast cancer registries and high-risk cancer genetic clinics (Breast Cancer Family Registry, the kConFab and a consortium of breast cancer genetics clinics in the United States and Spain). Additionally, Multiplex Ligation-dependent Probe Amplification was performed for 134 cases to detect large deletions.

RESULTS

No truncating mutations and no large deletions were detected. Six non-synonymous variants were found in seven families. Four (4/318 or 1.3%) are considered to be potentially pathogenic through in vitro and in silico analysis.

CONCLUSION

Potentially pathogenic germline CDH1 mutations in women with early-onset or familial lobular breast cancer are at most infrequent.

Association of 25(OH)D and PTH with metabolic syndrome and its traditional and nontraditional components

CONTEXT

Emerging evidence suggests that 25-hydroxy vitamin D [25(OH)D] and PTH may play a role in the etiology of the metabolic syndrome (MetS). However, evidence to date is limited and inconsistent, and few studies have examined associations with nontraditional MetS components.

OBJECTIVE

The objective of the study was to examine the association of vitamin D and PTH with MetS and its traditional and nontraditional components in a large multiethnic sample.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, we examined 654 participants from London and Toronto, Ontario, Canada, aged 30 yr and older with risk factors for type 2 diabetes.

MAIN OUTCOME MEASURES

Presence of MetS and its traditional and nontraditional components was measured.

RESULTS

Approximately 43% of the study participants were classified as having MetS. Higher 25(OH)D was significantly associated with a reduced presence of MetS after adjustment for age, sex, season, ethnicity, supplement use, physical activity, and PTH (odds ratio 0.76, 95% confidence interval 0.62-0.93). PTH was not associated with the presence of MetS after multivariate adjustment. Multivariate linear regression analyses indicated significant adjusted inverse associations of 25(OH)D with waist circumference, triglyceride level, fasting insulin, and alanine transaminase (P < 0.041). Elevated PTH was positively associated with waist circumference and high-density lipoprotein cholesterol (P < 0.04). Other associations between PTH and MetS components were attenuated after adjustment for adiposity.

CONCLUSIONS

Serum 25(OH)D, but not PTH, was significantly associated with MetS as well as a number of MetS components after multivariate adjustment. These results suggest that low 25(OH)D may play a role in the etiology of the MetS.

Assessing interactions between the associations of common genetic susceptibility variants, reproductive history and body mass index with breast cancer risk in the breast cancer association consortium: a combined case-control study

Introduction

Several common breast cancer genetic susceptibility variants have recently been identified. We aimed to determine how these variants combine with a subset of other known risk factors to influence breast cancer risk in white women of European ancestry using case-control studies participating in the Breast Cancer Association Consortium.

Methods

We evaluated two-way interactions between each of age at menarche, ever having had a live birth, number of live births, age at first birth and body mass index (BMI) and each of 12 single nucleotide polymorphisms (SNPs) (10q26-rs2981582 (FGFR2), 8q24-rs13281615, 11p15-rs3817198 (LSP1), 5q11-rs889312 (MAP3K1), 16q12-rs3803662 (TOX3), 2q35-rs13387042, 5p12-rs10941679 (MRPS30), 17q23-rs6504950 (COX11), 3p24-rs4973768 (SLC4A7), CASP8-rs17468277, TGFB1-rs1982073 and ESR1-rs3020314). Interactions were tested for by fitting logistic regression models including per-allele and linear trend main effects for SNPs and risk factors, respectively, and single-parameter interaction terms for linear departure from independent multiplicative effects.

Results

These analyses were applied to data for up to 26,349 invasive breast cancer cases and up to 32,208 controls from 21 case-control studies. No statistical evidence of interaction was observed beyond that expected by chance. Analyses were repeated using data from 11 population-based studies, and results were very similar.

Conclusions

The relative risks for breast cancer associated with the common susceptibility variants identified to date do not appear to vary across women with different reproductive histories or body mass index (BMI). The assumption of multiplicative combined effects for these established genetic and other risk factors in risk prediction models appears justified.

Vitamin D intake from food and supplements among Ontario women based on the US block food frequency questionnaire with and without modification for Canadian food values

OBJECTIVES

To measure and compare dietary vitamin D intake among women in Ontario using a modified Block 1998 (US) food frequency questionnaire (FFQ) before and after modification for Canadian-specific vitamin D food fortification.

METHODS

An age-stratified random sample of 3,471 women in Ontario (aged 25-74) was identified using random digit dialing methods. Standard US food values and a modified Canadian-specific vitamin D nutrient analysis were applied to the FFQ.

RESULTS

Intake of vitamin D from foods (Canadian nutrient analysis) was 5.3 +/- 3.4 microg/day (mean +/- SD) and 45% of women reported vitamin D intake from supplements. Total vitamin D intakes met the current Adequate Intakes of 5, 10 and 15 microg/day for only 62%, 47%, and 28% of women aged < or = 50, 51-70 and > or = 71, respectively. Relatively high agreement was found between the US and Canadian nutrient analysis methods of measuring vitamin D from food (weighted kappa = 0.74, 95% CI 0.72-0.76). Intake differences (US minus Canadian) ranged from -5.0 microg/day to +2.0 microg/day (1st-99th percentile); however, the mean difference was only -0.54 microg/day (95% CI: -0.58 to -0.50).

CONCLUSIONS

Lower than recommended total vitamin D intakes were observed among our study participants which may negatively impact the health status of women. Adjustment for Canadian food fortification and the inclusion of fatty fish had little impact on the measurement of vitamin D from food.

Increased cancer risks for relatives of very early-onset breast cancer cases with and without BRCA1 and BRCA2 mutations

Background:

Little is known regarding cancer risks for relatives of women with very early-onset breast cancer.

Methods:

We studied 2208 parents and siblings of 504 unselected population-based Caucasian women with breast cancer diagnosed before age 35 years (103 from USA, 124 from Canada and 277 from Australia), 41 known to carry a mutation (24 in BRCA1, 16 in BRCA2 and one in both genes). Cancer-specific standardised incidence ratios (SIRs) were estimated by comparing the number of affected relatives (50% verified overall) with that expected based on incidences specific for country, sex, age and year of birth.

Results:

For relatives of carriers, the female breast cancer SIRs were 13.13 (95% CI 6.57–26.26) and 12.52 (5.21–30.07) for BRCA1 and BRCA2, respectively. The ovarian cancer SIR was 12.38 (3.1–49.51) for BRCA1 and the prostate cancer SIR was 18.55 (4.64–74.17) for BRCA2. For relatives of non-carriers, the SIRs for female breast, prostate, lung, brain and urinary cancers were 4.03 (2.91–5.93), 5.25 (2.50–11.01), 7.73 (4.74–12.62), 5.19 (2.33–11.54) and 4.35 (1.81–10.46), respectively. For non-carriers, the SIRs remained elevated and were statistically significant for breast and prostate cancer when based on verified cancers.

Conclusion:

First-degree relatives of women with very early-onset breast cancer are at increased risk of cancers not explained by BRCA1 and BRCA2 mutations.

New antibiotic resistance Loci in the ribosomal region of yeast mitochondrial DNA

A large number of mitochondrial antibiotic-resistant mutants have been isolated following mutagenesis with manganese. These include several different phenotypic classes of mutants, as distinguished by cross-resistance patterns, that have been found to be allelic at cap1 or ery1; some have been found to be heteroallelic.--Seven chloramphenicol-resistant mutants have been identified that are nonallelic by recombination tests with the three loci (cap1, spi1 and ery1) previously identified in the ribosomal region. Four of these are allelic with each other and define a new locus, cap3; two others are allelic and define another new locus, cap2; the seventh maps at yet a different locus, cap4. One new spiramycin-resistant mutant has been identified that defines still another new locus, spi2. A variety of genetic techniques have been used to map these loci within the ribosomal region of the mitochondrial genome.-Manganese has been shown to be effective in inducing the mutation from omega(-) to omega(n) in many mutants that experience a simultaneous mutation at the closely linked cap1 locus. The omega(n) mutation has also been described in the cap4 mutant, and this locus has been shown to be more closely linked to omega than cap1 is to omega.

Association of vitamin D with insulin resistance and beta-cell dysfunction in subjects at risk for type 2 diabetes

OBJECTIVE

To examine cross-sectional associations of serum vitamin D [25-hydroxyvitamin D, 25(OH)D] concentration with insulin resistance (IR) and beta-cell dysfunction in 712 subjects at risk for type 2 diabetes.

RESEARCH DESIGN AND METHODS

Serum 25(OH)D was determined using a chemiluminescence immunoassay. Insulin sensitivity/resistance were measured using the Matsuda insulin sensitivity index for oral glucose tolerance tests (IS(OGTT)) and homeostasis model assessment of insulin resistance HOMA-IR. beta-Cell function was determined using both the insulinogenic index (IGI) divided by HOMA-IR (IGI/IR) and the insulin secretion sensitivity index-2 (ISSI-2). RESULTS Linear regression analyses indicated independent associations of 25(OH)D with IS(OGTT) and HOMA-IR (beta = 0.004, P = 0.0003, and beta = -0.003, P = 0.0072, respectively) and with IGI/IR and ISSI-2 (beta = 0.004, P = 0.0286, and beta = 0.003, P = 0.0011, respectively) after adjusting for sociodemographics, physical activity, supplement use, parathyroid hormone, and BMI.

CONCLUSIONS

Vitamin D may play a role in the pathogenesis of type 2 diabetes, as 25(OH)D concentration was independently associated with both insulin sensitivity and beta-cell function among individuals at risk of type 2 diabetes.

Optical spectroscopy of the breast in premenopausal women reveals tissue variation with changes in age and parity

PURPOSE

Variations during breast tissue development can influence later breast cancer risk. In particular, prolonged nulliparity increases risk. The authors used optical spectroscopy to compare breast tissue in 115 nulliparous women aged 31-40 (group 2) to 140 nulliparous women aged 18-21 (group 1), and also to 36 parous women aged 31-40 (group 3), and to evaluate the relationship between IGF-1 and optical breast tissue properties. IGF-1 has been linked in particular to premenopausal breast cancer.

METHODS

The authors measured the transmission spectra from 625 to 1050 nm wavelengths in each breast and determined regions of interindividual variation using principal components analysis. Spectral differences represent variation in lipid, water, oxyhemoglobin, deoxyhemoglobin, and collagen content. Group differences and the relationship with IGF-1 were estimated by linear regression after adjustment for multiple factors including height, weight, ethnicity, hormonal contraceptive use, and days since last menstrual period.

RESULTS

Principal component 3 scores were more negative in the older nulliparous women compared to either younger nulliparous women or to parous women of the same age (beta = -0.16, p = 0.008 for group 2 vs group 1 and beta = 0.51, p = 0.03 for group 3 vs group 2). These differences appear to indicate increased deoxyhemoglobin relative to oxyhemoglobin content in the tissue of the older, nulliparous premenopausal women compared to the other groups, which may be an indicator of proportionally increased proliferative tissue. Principal component 4 also differed between older and younger nulliparous women (beta = 0.08, p = 0.02 for group 2 vs. group 1) and was negatively associated with IGF-1 in younger women (beta = -0.0004, p = 0.03) and positively associated with IGF-1 in older women (beta = 0.001, p = 0.004).

CONCLUSIONS

Optical spectroscopy may be useful to identify breast tissue at increased risk of cancer development and track changes over time, particularly in young women where exposure to radiation is of particular concern. Additional work is needed to confirm the observed breast tissue differences and to determine the specific tissue chromophore changes with age and parity.

Abstract B28: Epigenetic contribution of Wnt antagonists SFRP1 and DKK1 as prognostic markers in colorectal cancer

Background: Aberrant Wnt pathway activation is a vital carcinogenic event in colorectal cancer (CRC). DKK1 and SFRP1 encode extracellular inhibitors of canonical and canonical/non-canonical Wnt signaling, respectively, that are frequently silenced by promoter hypermethylation in CRC. Despite their known tumor-suppressive roles, few studies have systematically examined the prognostic/predictive significance of methylation in these genes in tumor development. Using a population-based genetic epidemiological approach, we investigated the methylation status of DKK1 and SFRP1 in a large cohort of primary CRCs and correlations to patient clinicopathological data.

Methods: As part of a Canadian interdisciplinary initiative to study the genetic and environmental determinants of CRC, we accrued a large number of primary colorectal carcinoma cases diagnosed in the province of Ontario, representative of a heterogeneous population (n = 558), and in the province of Newfoundland, representative of a founder population (n = 650). We examined the methylation status of DKK1 and SFRP1 gene promoters in colorectal tumors and matched normal colon tissues using MethyLight assay, a semi-quantitative methylation detection technique. We examined correlations between methylation levels and frequency, and a comprehensive array of patient clinicopathological features such as: age, sex, tumor stage, grade, tumor MSI subtype, and clinical outcome. Statistical analysis was performed using 2-tailed Fisher's exact test, SPSS v16.

Results: Respective DKK1 and SFRP1 methylation frequencies were similar in Ontario (13%, 95%) and Newfoundland (14%, 94%). Methylation was highly tumor specific. DKK1 methylation was a strong predictor of the microsatellite instability (MSI) tumor subtype in Ontario (OR=13.7 [7.8, 24.2], p &lt; 0.001) and in Newfoundland (OR=3.9 [2.8, 5.6] p &lt; 0.001). SFRP1 methylation was a predictor against MSI tumors in Ontario (OR=0.25 [0.15, 0.52], p &lt; 0.001).

Conclusion: Our study highlights the prognostic role of DKK1 and SFRP1 methylation related to CRC tumor subtype and suggests a novel distinction between the relative involvements of different Wnt pathways in microsatellite stable vs. unstable CRC.

Citation Information: Clin Cancer Res 2010;16(7 Suppl):B28

Abstract B132: Risk factors for uncommon histologically defined subgroups of breast cancer using the Breast Cancer Family Registry

Breast cancer is a heterogeneous disease; risk factors may differ for histologically-defined subgroups. Because most breast cancers are of ductal or lobular histology, previous studies have been limited in their ability to evaluate risk factors in rarer histologies, such as medullary, mucinous, and tubular, due to small sample sizes. We evaluated risk factors for histologically-defined breast cancer subgroups (ductal, lobular, tubular, medullary, or mucinous) using population-based data from the Breast Cancer Family Registry. Data were available for 3260 incident breast cancer cases (including 92 cases of medullary, 90 cases of mucinous, and 86 cases of tubular histology) and 2997 unrelated controls. Several reproductive factors were associated with the risk of mucinous breast cancer, whereas cigarette smoking and body mass index (BMI) were associated with the risk of medullary breast cancer. For the mucinous subtype, we observed positive associations with nulliparity (OR=2.54, 95%CI 1.17–5.50) and age at first birth (OR=1.08, 95%CI=1.02–1.14, for each additional year of age), and an inverse association with age at menarche (≥13 vs. ≤11) (OR=0.52, 95%CI 0.29–0.94). These reproductive factors were not associated with other histologic subtypes. Mucinous cases were less likely than controls to have used oral contraceptives (OC use ≤ 5 years: OR=0.50, 95%CI 0.28–0.92; OC use &gt; 5 years, OR=0.45, 95%CI 0.24–0.84), and these findings did not differ by menopausal status. Oral contraceptive use was also inversely associated with tubular histology among premenopausal women only (OC use &gt; 5 years, OR=0.35, 95%CI 0.14–0.87), but was not associated with other histologic subtypes when compared with controls. Medullary histology was inversely associated with smoking status (former smoker vs. never smoker, OR=0.30, 95%CI 0.14–0.62), and positively associated with BMI (OR=1.05, 95%CI 1.01–1.09, for each one-unit increase in BMI). Other known breast cancer risk factors, such as hormone-replacement therapy (HRT), breastfeeding history, and alcohol use, were not associated with the any of the rarer subtypes. Family history of breast cancer was associated with increased risk of all histologic subtypes. If replicated, these findings suggest different patterns for selected breast cancer risk factors, such as parity, oral contraceptive use, and smoking, by tumor histology.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B132.

Abstract B127: Family history of breast cancer and risk of contralateral breast cancer

Purpose: Family history of breast cancer increases a woman's risk of developing a first primary breast cancer. A meta-analysis of case-control studies of first primary breast cancer reported an increased risk associated with having an affected first-degree relative (OR=2.1, 95% CI=2.0–2.2), and the risk was even greater when subject and relative were diagnosed before age 50 (OR=3.3, 95% CI=2.8–3.9) (Int J Ca 1997;71:800–9). In this study, we examined family history of breast cancer as a risk factor for developing asynchronous contralateral breast cancer (CBC) and compared these risks to those from the aforementioned meta-analysis.

Methods: The Women's Environmental Cancer and Radiation Epidemiology (WECARE) Study is a case-control study including women from five population-based cancer registries: four in the US and one in Denmark. The 708 cases in this study were women with CBC and the 1399 individually matched controls were women with unilateral breast cancer (UBC). All participants were initially diagnosed between January 1985 and December 2000 at age 54 years or younger, and were queried about family history of breast cancer among female first- and second-degree relatives. Multivariable-adjusted rate ratios (RR) and corresponding 95% confidence intervals (CI) were calculated using conditional logistic regression.

Results: Compared with women who reported no affected relatives, women with at least one first-degree relative with breast cancer were at increased risk of developing CBC (RR=2.1, 95% CI=1.6–2.7); the risk was greater when more than one relative was affected (RR=2.6, 95% CI=1.5–4.6), and was nearly 4-fold (RR=3.9, 95% CI=2.3–6.4) for women having a relative diagnosed with CBC. The risk of CBC was 3.1 (95% CI=1.8–5.3) when both relative and subject were diagnosed before age 45. When the relative was diagnosed before age 45, regardless of subject age, the risk of CBC was 2.6 (95% CI=1.7–4.1). Similarly, when the subject was diagnosed before age 45, regardless of relative's age, the risk of CBC was 2.5 (95% CI=1.7–3.6).

Conclusions: The risk of developing CBC is increased among women with a family history of breast cancer, and this risk is significantly greater among those with an affected relative with bilateral cancer, having more than one affected relative, and having relatives affected at young ages. Our results comparing CBC cases to UBC controls were similar to studies where UBC cases are compared to population controls.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B127.

Family history of hormonal cancers and colorectal cancer risk: a case-control study conducted in Ontario

Aggregation of cancers among families with highly penetrant genetic mutations such as hereditary nonpolyposis colorectal cancer is well-described. However, there is a paucity of data regarding familial aggregation of hormonal cancers (cancers of the breast, endometrial, ovarian and prostate) and colorectal cancer (CRC) in the general population. We investigated the association between having a first-degree family history of breast, endometrial, ovarian, or prostate cancer and CRC risk. Population-based CRC cases and controls were recruited by the Ontario Familial Colorectal Cancer Registry (OFCCR). Logistic regression was conducted to obtain odds ratio (OR) estimates and 95% confidence intervals (95% CIs). First-degree family history of breast cancer was associated with a modest, borderline statistically significant increased CRC risk (age-, sex-adjusted OR = 1.2, 95% CI = 1.0, 1.5). The magnitude of CRC risk was greatest if more than one first-degree kin had breast cancer (age-, sex-adjusted OR = 1.7, 95% CI = 1.0, 2.0), as well as if the kin was diagnosed at >50 years of age (age-, sex-adjusted OR = 1.4, 95% CI = 1.1, 1.8). Family history of ovarian cancer was associated with reduced CRC risk (multivariate-adjusted OR = 0.6, 95% CI = 0.3, 1.0). Although statistically significant increases in CRC risk were observed in the age-, sex-adjusted OR estimates for family history of endometrial and prostate cancers, the associations were no longer significant after multivariate-adjustment. In conclusion, individuals with a first-degree kin with breast cancer may have a modest increased risk for CRC compared to individuals without.

Newly discovered breast cancer susceptibility loci on 3p24 and 17q23.2

Genome-wide association studies (GWAS) have identified seven breast cancer susceptibility loci, but these explain only a small fraction of the familial risk of the disease. Five of these loci were identified through a two-stage GWAS involving 390 familial cases and 364 controls in the first stage, and 3,990 cases and 3,916 controls in the second stage. To identify additional loci, we tested over 800 promising associations from this GWAS in a further two stages involving 37,012 cases and 40,069 controls from 33 studies in the CGEMS collaboration and Breast Cancer Association Consortium. We found strong evidence for additional susceptibility loci on 3p (rs4973768: per-allele OR = 1.11, 95% CI = 1.08-1.13, P = 4.1 x 10(-23)) and 17q (rs6504950: per-allele OR = 0.95, 95% CI = 0.92-0.97, P = 1.4 x 10(-8)). Potential causative genes include SLC4A7 and NEK10 on 3p and COX11 on 17q.

Alcohol intake and cigarette smoking and risk of a contralateral breast cancer: The Women's Environmental Cancer and Radiation Epidemiology Study

Women with primary breast cancer are at increased risk of developing second primary breast cancer. Few studies have evaluated risk factors for the development of asynchronous contralateral breast cancer in women with breast cancer. In the Women's Environmental Cancer and Radiation Epidemiology Study (1985-2001), the roles of alcohol and smoking were examined in 708 women with asynchronous contralateral breast cancer (cases) compared with 1,399 women with unilateral breast cancer (controls). Cases and controls aged less than 55 years at first breast cancer diagnosis were identified from 5 population-based cancer registries in the United States and Denmark. Controls were matched to cases on birth year, diagnosis year, registry region, and race and countermatched on radiation treatment. Risk factor information was collected by telephone interview. Rate ratios and 95% confidence intervals were estimated by using conditional logistic regression. Ever regular drinking was associated with an increased risk of asynchronous contralateral breast cancer (rate ratio = 1.3, 95% confidence interval: 1.0, 1.6), and the risk increased with increasing duration (P = 0.03). Smoking was not related to asynchronous contralateral breast cancer. In this, the largest study of asynchronous contralateral breast cancer to date, alcohol is a risk factor for the disease, as it is for a first primary breast cancer.

Family-based genetic association study of insulin-like growth factor I microsatellite markers and premenopausal breast cancer risk

Several studies suggest that higher circulating insulin-like growth factor I (IGF-I) levels are associated with premenopausal breast cancer risk. Breast cancer risk and circulating IGF-I concentration appear to be partly heritable, thus genetic variation at IGF1 could influence IGF-I levels and breast cancer risk. We investigated the association of IGF1 CA repeat variants with premenopausal breast cancer risk using a family-based design. The study sample included 840 families from the Ontario Familial Breast Cancer Registry (OFBCR) and the Australian Breast Cancer Family Registry (ABCFR). Three CA repeat variants, at 5', 3', and in intron 2 were genotyped (5'CA, 3'CA, In2CA). We found several nominally significant associations. The 5'CA-21 allele (P = 0.03) and In2CA-212 allele (P = 0.04) were associated with lower risk, and the In2CA-216 allele with higher risk (P = 0.04) for the combined ABCFR-OFBCR. These associations were not significant after taking into account multiple comparisons. In2CA-216 was more strongly associated with risk when we used a recessive instead of an additive model (P = 0.01). 5'CA alleles of repeat length 18-20 were associated with higher risk (P = 0.02), and 5'CA alleles of >20 repeats were associated with lower risk (P = 0.01). These associations were significant in the OFBCR (In2CA-216 recessive, P = 0.02; 5'CA 18-20 and >20 allele grouping, P = 0.01) but not strongly supported by the ABCFR (In2CA-216 recessive, P = 0.14; 5'CA 18-20, P = 0.25; 5'CA >20, P = 0.20). The associations we found could be due to chance as many comparisons were made. Our results do not strongly support an association between these IGF1 variants and breast cancer risk.

Vitamin D from dietary intake and sunlight exposure and the risk of hormone-receptor-defined breast cancer

Evidence has emerged for a role of vitamin D in the development of breast cancer, and there is some suggestion that its antiproliferative effect is greater in hormone-receptor-positive cells. Few epidemiologic studies have considered the association between vitamin D and hormone-receptor-defined breast cancer, and the results are conflicting. Considering 759 cases and 1,135 controls from a case-control study (Ontario, Canada, 2003-2005), the authors examined the association between vitamin D intake at specific ages and combined estrogen-receptor- (ER) and progesterone-receptor- (PR) defined breast cancer. While increased intake of vitamin D (from the sun and diet) was most consistently associated with a significantly reduced risk of ER+/PR+ tumors (e.g., odds ratio = 0.76, 95% confidence interval: 0.59, 0.97 for use of cod liver oil during adolescence), comparable nonsignificant associations were found for receptor-negative (ER-/PR-) (odds ratio = 0.74, 95% confidence interval: 0.53, 1.04) and mixed (ER+/PR-) (odds ratio = 0.79, 95% confidence interval: 0.51, 1.22) tumors. This study suggests that vitamin D is associated with a reduced risk of breast cancer regardless of ER/PR status of the tumor. Future studies with a larger number of receptor-negative and mixed tumors are required.

Association between transillumination breast spectroscopy and quantitative mammographic features of the breast

Transillumination breast spectroscopy (TiBS) uses nonionizing optical radiation to gain information about tissue properties directly from the breast. TiBS measurements were obtained from 225 women with normal mammograms. Principal component analysis was used to reduce the spectral data set into four principal components and to generate four TiBS scores (t1-t4) for each woman. These components and scores represent light scattering, water, lipid, and hemoglobin content. Percent density, dense area, and nondense area were measured using Cumulus. The association between TiBS scores and quantitative mammographic features was analyzed using linear regression stratified by menopausal status and adjusted for body mass index. Among premenopausal women, t1 and t3 were significantly associated with percent density (beta t1 = -0.14, P = 0.04; beta t3 = -2.43, P < 0.0001), whereas t2 and t3 were significantly associated with dense area (beta t2 = -1.57, P < 0.0001; beta t3 = -2.54, P < 0.0001). Among postmenopausal women, t1, t3, and t4 were significantly associated with percent density (beta t1 = -0.30, P < 0.0001; beta t3 = -2.51, P < 0.0001; beta t4 = 4.75, P < 0.0001) and dense area (beta t1 = -0.19, P = 0.004; beta t3 = -2.13, P = 0.002; beta t4 = 5.02, P < 0.0001). Scores t2 and t4 were also significantly correlated with age among postmenopausal women (rt2 = 0.41 and rt4 = -0.36). Given the association with quantitative mammographic features and tissue changes related to age and menopause, TiBS scores may prove useful as intermediate markers in studies of breast cancer etiology and prevention.

Association of vitamin D related information from a telephone interview with 25-hydroxyvitamin D

Vitamin D may be associated with reduced risks of several types of cancer, including colon, prostate, and breast. We examined the relationship between vitamin D-related questions administered in a telephone interview and serum 25-hydroxyvitamin D [25(OH)D]. Three hundred and eight eligible women were randomly selected from controls in a breast cancer case-control study. Questions pertaining to sun exposure and dietary sources of vitamin D over the previous 4 weeks were asked in both summer and winter. We assessed the association between questionnaire-derived items and 25(OH)D using multiple linear regression. There were 217 participating women, 203 in summer and 213 in winter. Models were adjusted for age, body mass index, and skin color. Number of days when more than 0.5 hour was spent outdoors per week ("7" versus "<7" beta = 11.12; P = 0.01), limb coverage ("no" beta = 24.90 and "partial" beta = 8.15 versus "yes"; P = 0.0001), and milk intake (glasses/wk; ">10" beta = 18.94, ">5-10" beta = 9.16, and "1-5" beta = 7.90 versus "<1"; P = 0.02) best predicted 25(OH)D in the summer. The best predictors in the winter were sunlamp use ("yes" beta = 27.97 versus "no"; P = 0.01), milk intake (glasses/wk; ">10" beta = 14.54, ">5-10" beta = 11.54, and "1-5" beta = 2.15 versus "<1"; P = 0.01), and vitamin D-containing supplements ("high" beta = 17.30 and "moderate" beta = 13.82 versus "none"; P = 0.0006). The R(2) was 0.29 for the summer model and was 0.21 for the winter model. Overall, there was evidence to suggest that questions designed to assess vitamin D exposure were in fact related to serum 25(OH)D.

Combined effect of CCND1 and COMT polymorphisms and increased breast cancer risk

BACKGROUND

Estrogens are crucial tumorigenic hormones, which impact the cell growth and proliferation during breast cancer development. Estrogens are metabolized by a series of enzymes including COMT, which converts catechol estrogens into biologically non-hazardous methoxyestrogens. Several studies have also shown the relationship between estrogen and cell cycle progression through activation of CCND1 transcription.

METHODS

In this study, we have investigated the independent and the combined effects of commonly occurring CCND1 (Pro241Pro, A870G) and COMT (Met108/158Val) polymorphisms to breast cancer risk in two independent Caucasian populations from Ontario (1228 breast cancer cases and 719 population controls) and Finland (728 breast cancer cases and 687 population controls). Both COMT and CCND1 polymorphisms have been previously shown to impact on the enzymatic activity of the coded proteins.

RESULTS

Here, we have shown that the high enzymatic activity genotype of CCND1High (AA) was associated with increased breast cancer risk in both the Ontario [OR: 1.3, 95%CI (1.0-1.69)] and the Finland sample [OR: 1.4, 95%CI (1.01-1.84)]. The heterozygous COMTMedium (MetVal) and the high enzymatic activity of COMTHigh (ValVal) genotype was also associated with breast cancer risk in Ontario cases, [OR: 1.3, 95%CI (1.07-1.68)] and [OR: 1.4, 95%CI (1.07-1.81)], respectively. However, there was neither a statistically significant association nor increased trend of breast cancer risk with COMTHigh (ValVal) genotypes in the Finland cases [OR: 1.0, 95%CI (0.73-1.39)]. In the combined analysis, the higher activity alleles of the COMT and CCND1 is associated with increased breast cancer risk in both Ontario [OR: 2.22, 95%CI (1.49-3.28)] and Finland [OR: 1.73, 95%CI (1.08-2.78)] populations studied. The trend test was statistically significant in both the Ontario and Finland populations across the genotypes associated with increasing enzymatic activity.

CONCLUSION

Using two independent Caucasian populations, we have shown a stronger combined effect of the two commonly occurring CCND1 and COMT genotypes in the context of breast cancer predisposition.

MSH2 118T>C and MSH6 159C>T promoter polymorphisms and the risk of colorectal cancer

The most important indicator of colorectal cancer (CRC) risk is the presence of family history of the disease. Inherited genetic changes, such as single nucleotide polymorphisms, in key candidate genes may contribute to CRC risk. We investigated whether promoter polymorphisms in DNA mismatch repair (MMR) genes MSH2 and MSH6 are associated with the risk of CRC. We genotyped 929 CRC patients and 1098 control subjects from Ontario, and 467 patients and 344 controls from Newfoundland and Labrador, for two promoter polymorphisms in the MMR genes MSH2 and MSH6 using the fluorogenic 5' nuclease assay. We used unconditional logistic regression to evaluate the association between each polymorphism and CRC after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathological features were evaluated with a Pearson's chi-squared test or Fisher's exact test. All statistical tests were two sided. We observed strong associations between the MSH2 -118T>C polymorphism and family history of CRC based on the Amsterdam criteria I (P = 0.005) and Amsterdam criteria I and II (P = 0.036) among cases from Ontario. This association was especially evident among female CRC patients in Ontario (for Amsterdam criteria I, and I and II combined, P = 0.003 and P = 0.0001, respectively). The MSH2 -118T>C polymorphism was associated with strong family history of CRC in Ontario patients.

Medical radiation exposure and breast cancer risk: findings from the Breast Cancer Family Registry

Moderate to high-dose radiotherapy is known to increase the risk of breast cancer. Uncertainties remain about the effects of low-dose chest X-rays, particularly in individuals at increased genetic risk. We analyzed case-control data from the Breast Cancer Family Registry. Self-reported data on therapeutic and diagnostic radiation exposures to the chest were available for 2,254 breast cancer cases and 3,431 controls (1,556 unaffected sisters and 1,875 unrelated population controls). We used unconditional logistic regression analyses to estimate odds ratios (OR) and 95% confidence intervals (CI) associated with radiation exposure, after adjusting for age, study center, country of birth, and education. Increased risks for breast cancer were found for women who had radiotherapy for a previous cancer (OR=3.55, CI=1.47-8.54) and diagnostic chest X-rays for tuberculosis (OR=2.49, CI=1.82-3.40) or pneumonia (OR=2.19, CI=1.38-3.47). Risks were highest for women with a large number of exposures at a young age or exposed in earlier calendar years. There was no evidence of increased risk associated with other diagnostic chest X-rays (not including tuberculosis or pneumonia), both in women with and without indicators of increased genetic risk (i.e., diagnosed at age <40 years or family history of breast cancer). Given the widespread and increasing use of medical diagnostic radiation, continued surveillance of breast cancer risk is warranted, particularly in women at specific genetic risk, such as those carrying mutations in BRCA1 or BRCA2.

Ovarian cysts and breast cancer: results from the Women’s Contraceptive and Reproductive Experiences Study

A diagnosis of ovarian cysts is likely an indicator of hormonal milieu and thus may be related to breast cancer risk. Recent studies have reported an inverse relationship between prior ovarian cyst diagnosis and breast cancer risk. We evaluated this relationship in the Women's Contraceptive and Reproductive Experiences (CARE) Study, a population-based case-control study conducted in Atlanta, Detroit, Philadelphia, Los Angeles, and Seattle. Cases had first primary invasive breast cancer diagnosed between 1994 and 1998 at ages 35-64 years. African American women were over-sampled. Controls were identified through random digit dialling and were frequency matched to cases on centre, race, and five-year age group. A total of 4575 cases and 4682 controls were interviewed. We used unconditional logistic regression adjusted for age and study centre within racial groups to estimate the odds ratio (OR) and 95% confidence interval (CI) for the relationship between prior ovarian cysts and breast cancer. Ovarian cyst diagnosis was associated with a significantly reduced risk among Caucasians (OR=0.85, 95% CI 0.76-0.96) and among African Americans (OR=0.68, 95% CI 0.57-0.81). The association in Caucasians was not significant within subgroups defined by menopausal status, hormone use, or gynecological surgery while the OR estimates in African Americans were consistently lower and frequently significant. These data are consistent with the previously reported inverse association between ovarian cysts and breast cancer, but the evidence for a relationship was stronger in African Americans than Caucasians. Additional studies are required to determine the specific cyst type(s) responsible for the observed relationship.

No association between 25-hydroxyvitamin D and mammographic density

There is increasing evidence that vitamin D may protect against breast cancer. Some studies have suggested that dietary and supplemental vitamin D is associated with reduced mammographic density, which is highly associated with breast cancer risk, although this evidence is not entirely consistent. We investigated a possible association between circulating 25-hydroxyvitamin D (25OHD), the best indicator of vitamin D status, and quantitative mammographic density in the Minnesota Breast Cancer Family Study. Mean values of mammographic density (both percent and area densities) and circulating levels of 25OHD were compared across categories of covariates using ANOVA. Models were adjusted for age and body mass index, as well as other covariates, and also stratified by dietary calcium intake, menopause, and season. Serum, mammographic density, and questionnaire data were available from 487 women [133 premenopausal and 354 postmenopausal; mean age, 56.4 years (range, 27-85 years)] without breast cancer, and for 73%, the blood was drawn within 1 year of their mammogram. No evidence was found for an association between 25OHD and either percent density or total dense area. There was also no evidence for any association when the data were stratified by season of sample (winter and summer) or menopause. However, both percent density and dense area were lowest among those in the highest vitamin D quartile with calcium intake above the median. Unlike some previous reports, vitamin D does not seem to be related to mammographic density in this cohort.

Polymorphisms cMyc-N11S and p27-V109G and breast cancer risk and prognosis

BACKGROUND

cMyc and p27 are key genes implicated in carcinogenesis. Whether polymorphisms in these genes affect breast cancer risk or prognosis is still unclear. In this study, we focus on a rare non-synonymous polymorphism in cMyc (N11S) and a common polymorphism in p27 (V109G) and determine their role in risk and prognosis using data collected from the Ontario Breast Cancer Family Registry.

METHODS

Risk factor data was collected at baseline on a large group of women (cases = 1,115 and population-based controls = 710) and clinical data (including treatment and follow-up) were collected prospectively by periodic review of medical records for a subset of cases (N = 967) for nearly a decade. A centralized pathology review was conducted. Unconditional logistic regression was used to determine the association of polymorphisms with breast cancer risk and the Cox proportional hazards model was used to determine their association with survival.

RESULTS

Our results suggest that while cMyc-N11S can be considered a putatively functional polymorphism located in the N-terminal domain, it is not associated with risk, tumor characteristics or survival. The p27-G109 allele was associated with a modest protective effect in adjusted analyses and higher T stage. We found no evidence to suggest that p27-V109G alone or in combination with cMyc-N11S was associated with survival. Age at onset and first-degree family history of breast or ovarian cancer did not significantly modify the association of these polymorphisms with breast cancer risk.

CONCLUSION

Further work is recommended to understand the potential functional role of these specific non-synonymous amino acid changes and a larger, more comprehensive investigation of genetic variation in these genes (e.g., using a tagSNP approach) in combination with other relevant genes is needed as well as consideration for treatment effects when assessing their potential role in prognosis.

Assessing breast tissue density by transillumination breast spectroscopy (TIBS): an intermediate indicator of cancer risk

Risk assessment by parenchymal density pattern, a strong physical indicator of future breast cancer risk, is available with the onset of mammographic screening programmes. However, due to the use of ionizing radiation, mammography is not recommended for use in younger women, thereby rendering risk assessment unattainable at an earlier age. Visible and near infrared light was used on 292 women with radiologically normal mammograms to determine whether transillumination breast spectroscopy (TIBS) can identify women with a high parenchymal density pattern as an intermediate indicator of breast cancer risk. Principal component analysis (PCA) was used to reduce the spectral data and generate density scores for each woman. To assess the accuracy of TIBS, logistic regression was used to calculate crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) for each score. Receiver operator characteristic (ROC) curves and area under the curve (AUC) were also calculated for the crude and adjusted logistic models. Optical information relating to tissue chromophores, such as water, lipid and haemoglobin content, was sufficient to identify women with high parenchymal density. The resulting AUC for the final and most parsimonious multivariate logistic model was 0.922 (95% CI 0.878-0.967). TIBS provides information correlating to high parenchymal density and is a promising tool for risk assessment, particularly for younger women.

Vitamin D and reduced risk of breast cancer: a population-based case-control study

BACKGROUND

Vitamin D, antiproliferative and proapoptotic in breast cancer cell lines, can reduce the development of mammary tumors in carcinogen-exposed rats. Current evidence in humans is limited with some suggestion that vitamin D-related factors may reduce the risk of breast cancer. We conducted a population-based case-control study to assess the evidence for a relationship between sources of vitamin D and breast cancer risk.

METHODS

Women with newly diagnosed invasive breast cancer were identified from the Ontario Cancer Registry. Women without breast cancer were identified through randomly selected residential telephone numbers. Telephone interviews were completed for 972 cases and 1,135 controls. Odds ratios (OR) and 95% confidence intervals (CI) for vitamin D-related variables were estimated using unconditional logistic regression with adjustment for potential confounders.

RESULTS

Reduced breast cancer risks were associated with increasing sun exposure from ages 10 to 19 (e.g., OR, 0.65; 95% CI, 0.50-0.85 for the highest quartile of outdoor activities versus the lowest; P for trend = 0.0006). Reduced risk was also associated with cod liver oil use (OR, 0.76; 95% CI, 0.62-0.92) and increasing milk consumption (OR, 0.62 95% CI 0.45-0.86 for >or=10 glasses per week versus none; P for trend = 0.0004). There was weaker evidence for associations from ages 20 to 29 and no evidence for ages 45 to 54.

CONCLUSION

We found strong evidence to support the hypothesis that vitamin D could help prevent breast cancer. However, our results suggest that exposure earlier in life, particularly during breast development, maybe most relevant. These results should be confirmed.

MLH1 -93G>A promoter polymorphism and the risk of microsatellite-unstable colorectal cancer

BACKGROUND

Although up to 30% of patients with colorectal cancer have a positive family history of colorectal neoplasia, few colorectal cancers can be explained by mutations in high-penetrance genes. We investigated whether polymorphisms in DNA mismatch repair genes are associated with the risk of colorectal cancer.

METHODS

We genotyped 929 case patients and 1098 control subjects from Ontario and 430 case patients and 275 control subjects from Newfoundland and Labrador for five polymorphisms in the mismatch repair genes MLH1 and MSH2 with the fluorogenic 5' nuclease assay. Tumor microsatellite instability (MSI) was determined with a polymerase chain reaction-based method; MSI status was assigned as high (MSI-H, > or = 30% unstable markers among all markers tested), low (MSI-L, <30% markers unstable), or stable (MSS, no unstable markers). We used unconditional logistic regression to evaluate the association between each polymorphism and colorectal cancer after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathologic features were evaluated with a Pearson's chi-square or Fisher's exact test. All statistical tests were two-sided.

RESULTS

We observed strong associations between the MLH1 -93G>A polymorphism and MSI-H tumors among case patients from Ontario (P = .001) and Newfoundland (P = .003). When compared with the control populations, homozygosity for the MLH1 -93G>A variant allele was associated with MSI-H tumors among case patients in Ontario (adjusted odds ratio [OR] = 3.23, 95% confidence interval [CI] = 1.65 to 6.30) and in Newfoundland (OR = 8.88, 95% CI = 2.33 to 33.9), as was heterozygosity among case patients in Ontario (OR = 1.84, 95% CI = 1.20 to 2.83) and in Newfoundland (OR = 2.56, 95% CI = 1.14 to 5.75). Genotype frequencies were similar among case patients with MSS and MSI-L tumors and control subjects, and the majority of homozygous variant carriers had MSS tumors. Among case patients from Ontario, an association between the MLH1 -93G>A polymorphism and a strong family history of colorectal cancer (for Amsterdam criteria I and II, P = .004 and P = .02, respectively) was observed.

CONCLUSION

In two patient populations, the MLH1 -93G>A polymorphism was associated with an increased risk of MSI-H colorectal cancer.

Alcohol metabolism, alcohol intake, and breast cancer risk: a sister-set analysis using the Breast Cancer Family Registry

Moderate alcohol intake has been consistently associated with a modest (30-50%) increase in breast cancer risk, but it remains unclear if certain individuals have higher susceptibility to the harmful effects of alcohol intake. Individuals differ in their ability to metabolize alcohol through genetic differences in alcohol dehydrogenase (ADH), the enzyme that catalyzes the oxidation of approximately 80% of ethanol to acetaldehyde, a known carcinogen. Using data from the Breast Cancer Family Registry (n = 811 sister sets), we examined whether sisters with breast cancer differ with respect to alcohol consumption and alcohol metabolism (measured by polymorphisms in ADH1B and ADH1C) compared to their sisters without breast cancer. Neither alcohol drinking nor alcohol metabolizing ADH1B and ADH1C genotypes were associated with breast cancer risk. However, only 19% and 42% of sisters were discordant by ADH1B and ADH1C, respectively, and even fewer were discordant by both genotype and alcohol intake, making it difficult to detect differences if they existed.

Comparison of self-reported lifetime sun exposure with two methods of cutaneous microtopography

There is currently no "gold standard" for measuring lifetime sun exposure. Exploration of alternatives to self-reports is important for examining illnesses related to ultraviolet light exposure. Using skin replicas obtained from 184 controls in a breast cancer case-control study (Toronto, Ontario, Canada, 2004-2005), the authors compared self-reported indicators of lifetime sun exposure with two measures of cutaneous microtopography, the Beagley-Gibson system and skin line counts. With the Beagley-Gibson system, significantly increased odds ratios were found for age (odds ratio (OR) = 1.10, 95% confidence interval (CI): 1.05, 1.16), spending 7 days outside per week during the summer (OR = 3.33, 95% CI: 1.48, 7.50), and lifetime number of sunlamp sessions. Significantly decreased odds ratios were found for having darker skin, ever giving birth, and ever using sunlamps. With the skin line count approach, significant positive associations were found for age (OR = 2.31, 95% CI: 1.23, 4.35), age squared, duration of working in outdoor jobs (OR = 0.88, 95% CI: 0.79, 0.98), and average number of outdoor activities per week at ages 20-29 years (OR = 1.05, 95% CI: 1.00, 1.10). While the Beagley-Gibson method was associated with more variables than the skin line count method, both methods require further refinement before graded skin replicas can be recommended as a substitute for self-report measures.

Population-based estimates of breast cancer risks associated with ATM gene variants c.7271T>G and c.1066-6T>G (IVS10-6T>G) from the Breast Cancer Family Registry

The ATM gene variants segregating in ataxia-telangiectasia families are associated with increased breast cancer risk, but the contribution of specific variants has been difficult to estimate. Previous small studies suggested two functional variants, c.7271T>G and c.1066-6T>G (IVS10-6T>G), are associated with increased risk. Using population-based blood samples we found that 7 out of 3,743 breast cancer cases (0.2%) and 0 out of 1,268 controls were heterozygous for the c.7271T>G allele (P=0.1). In cases, this allele was more prevalent in women with an affected mother (odds ratio [OR]=5.5, 95% confidence interval [CI]=1.2-25.5; P=0.04) and delayed child-bearing (OR=5.1; 95% CI=1.0-25.6; P=0.05). The estimated cumulative breast cancer risk to age 70 years (penetrance) was 52% (95% CI=28-80%; hazard ratio [HR]=8.6; 95% CI=3.9-18.9; P<0.0001). In contrast, 13 of 3,757 breast cancer cases (0.3%) and 10 of 1,268 controls (0.8%) were heterozygous for the c.1066-6T>G allele (OR=0.4; 95% CI=0.2-1.0; P=0.05), and the penetrance was not increased (P=0.5). These findings suggest that although the more common c.1066-6T>G variant is not associated with breast cancer, the rare ATM c.7271T>G variant is associated with a substantially elevated risk. Since c.7271T>G is only one of many rare ATM variants predicted to have deleterious consequences on protein function, an effective means of identifying and grouping these variants is essential to assess the contribution of ATM variants to individual risk and to the incidence of breast cancer in the population.

Influence of young age at diagnosis and family history of breast or ovarian cancer on breast cancer outcomes in a population-based cohort study

PURPOSE

The objective of this study was to examine the association of: (i) diagnosis at age </=35, (ii) first-degree family history of breast or ovarian cancer (BOC) and (iii) a research based definition of genetic risk, with tumor characteristics, treatment and survival in breast cancer (BC).

PATIENTS AND METHODS

Consenting female participants in the population-based Ontario Familial Breast Cancer Registry diagnosed with primary invasive BC between 1996 and 1998 were followed prospectively until 2005.

RESULTS

Among 967 women, 105 were </=35 years old at diagnosis and 686 were classified as genetic risk cases, including 349 with a first-degree family history. Individuals diagnosed at age </=35 were more likely to self-detect tumors, to present with inflammatory BC, to have invasive ductal carcinoma of no special type, high T stage, and tumors with lymphovascular invasion (LVI), high grade and negative estrogen receptors. Younger women were more likely to receive chemotherapy and less likely to receive hormonal therapy. Diagnosis </=35 years old was associated with significantly reduced distant recurrence free survival, an effect that did not persist after adjustment for tumor and treatment related variables. Poor outcomes were restricted to younger women with hormone responsive BC. Family history was associated with increased rates of mammographic detection of BC, lower tumor stage and less frequent inflammatory BC, but had no association with BC outcomes.

CONCLUSION

Women diagnosed with BC at age </=35 have more aggressive tumors; these adverse tumor characteristics, rather than age, lead to poor outcomes. Family history was not associated with survival.

BRCA1 and BRCA2 mutation carriers, oral contraceptive use, and breast cancer before age 50

BACKGROUND

Understanding the effect of oral contraceptives on risk of breast cancer in BRCA1 or BRCA2 mutation carriers is important because oral contraceptive use is a common, modifiable practice.

METHODS

We studied 497 BRCA1 and 307 BRCA2 mutation carriers, of whom 195 and 128, respectively, had been diagnosed with breast cancer. Case-control analyses were conducted using unconditional logistic regression with adjustments for family history and familial relationships and were restricted to subjects with a reference age under 50 years.

RESULTS

For BRCA1 mutation carriers, there was no significant association between risk of breast cancer and use of oral contraceptives for at least 1 year [odds ratio (OR), 0.77; 95% confidence interval (95% CI), 0.53-1.12] or duration of oral contraceptive use (P(trend) = 0.62). For BRCA2 mutation carriers, there was no association with use of oral contraceptives for at least 1 year (OR, 1.62; 95% CI, 0.90-2.92); however, there was an association of elevated risk with oral contraceptive use for at least 5 years (OR, 2.06; 95% CI, 1.08-3.94) and with duration of use (OR(trend) per year of use, 1.08; P = 0.008). Similar results were obtained when we considered only use of oral contraceptives that first started in 1975 or later.

CONCLUSIONS

We found no evidence overall that use of oral contraceptives for at least 1 year is associated with breast cancer risk for BRCA1 and BRCA2 mutation carriers before age 50. For BRCA2 mutation carriers, use of oral contraceptives may be associated with an increased risk of breast cancer among women who use them for at least 5 years. Further studies reporting results separately for BRCA1 and BRCA2 mutation carriers are needed to resolve this important issue.

The role of self-defined race/ethnicity in population structure control

Population-based association studies are powerful tools for the genetic mapping of complex diseases. However, this method is sensitive to potential confounding by population structure. While statistical methods that use genetic markers to detect and control for population structure have been the focus of current literature, the utility of self-defined race/ethnicity in controlling for population structure has been controversial. In this study of 1334 individuals, who self-identified as either African American, European American or Hispanic, we demonstrated that when the true underlying genetic structure and the self-defined racial/ethnic groups were roughly in agreement with each other, the self-defined race/ethnicity information was useful in the control of population structure.

The CHEK2*1100delC allelic variant and risk of breast cancer: screening results from the Breast Cancer Family Registry

CHEK2, a serine-threonine kinase, is activated in response to agents, such as ionizing radiation, which induce DNA double-strand breaks. Activation of CHEK2 can result in cell cycle checkpoint arrest or apoptosis. One specific variant, CHEK2*1100delC, has been associated with an increased risk of breast cancer. In this population-based study, we screened 2,311 female breast cancer cases and 496 general population controls enrolled in the Ontario and Northern California Breast Cancer Family Registries for this variant (all controls were Canadian). Overall, 30 cases and one control carried the 1100delC allele. In Ontario, the weighted mutation carrier frequency among cases and controls was 1.34% and 0.20%, respectively [odds ratio (OR), 6.65; 95% confidence interval (95% CI), 2.37-18.68]. In California, the weighted population mutation carrier frequency in cases was 0.40%. Across all cases, 1 of 524 non-Caucasians (0.19%) and 29 of 1,775 Caucasians (1.63%) were mutation carriers (OR, 0.12; 95% CI, 0.02-0.89). Among Caucasian cases >45 years age at diagnosis, carrier status was associated with history of benign breast disease (OR, 3.18; 95% CI, 1.30-7.80) and exposure to diagnostic ionizing radiation (excluding mammography; OR, 3.21; 95% CI, 1.13-9.14); compared with women without exposure to ionizing radiation, the association was strongest among women exposed >15 years before diagnosis (OR, 4.28; 95% CI, 1.50-12.20) and among those who received two or more chest X-rays (OR, 3.63; 95% CI, 1.25-10.52). These data supporting the biological relevance of CHEK2 in breast carcinogenesis suggest that further studies examining the joint roles of CHEK2*1100delC carrier status and radiation exposure may be warranted.

SNP-SNP interactions in breast cancer susceptibility

BACKGROUND

Breast cancer predisposition genes identified to date (e.g., BRCA1 and BRCA2) are responsible for less than 5% of all breast cancer cases. Many studies have shown that the cancer risks associated with individual commonly occurring single nucleotide polymorphisms (SNPs) are incremental. However, polygenic models suggest that multiple commonly occurring low to modestly penetrant SNPs of cancer related genes might have a greater effect on a disease when considered in combination.

METHODS

In an attempt to identify the breast cancer risk conferred by SNP interactions, we have studied 19 SNPs from genes involved in major cancer related pathways. All SNPs were genotyped by TaqMan 5'nuclease assay. The association between the case-control status and each individual SNP, measured by the odds ratio and its corresponding 95% confidence interval, was estimated using unconditional logistic regression models. At the second stage, two-way interactions were investigated using multivariate logistic models. The robustness of the interactions, which were observed among SNPs with stronger functional evidence, was assessed using a bootstrap approach, and correction for multiple testing based on the false discovery rate (FDR) principle.

RESULTS

None of these SNPs contributed to breast cancer risk individually. However, we have demonstrated evidence for gene-gene (SNP-SNP) interaction among these SNPs, which were associated with increased breast cancer risk. Our study suggests cross talk between the SNPs of the DNA repair and immune system (XPD-[Lys751Gln] and IL10-[G(-1082)A]), cell cycle and estrogen metabolism (CCND1-[Pro241Pro] and COMT-[Met108/158Val]), cell cycle and DNA repair (BARD1-[Pro24Ser] and XPD-[Lys751Gln]), and within carcinogen metabolism (GSTP1-[Ile105Val] and COMT-[Met108/158Val]) pathways.

CONCLUSION

The importance of these pathways and their communication in breast cancer predisposition has been emphasized previously, but their biological interactions through SNPs have not been described. The strategy used here has the potential to identify complex biological links among breast cancer genes and processes. This will provide novel biological information, which will ultimately improve breast cancer risk management.

Functional characterization of novel presenilin-2 variants identified in human breast cancers

We identified in breast cancer cases two germline alterations, R62H and R71W, in presenilin-2 (PS-2), a gene involved in familial Alzheimer's disease (FAD). The role of these alleles in FAD is unclear, but neither allele affected Abeta(42)/Abeta(40) ratio. However, both R62H and R71W alterations compromised PS-2 function in Notch signaling in Caenorhabditis elegans and cell growth inhibition in mouse embryonic fibroblasts, and these effects were dependent on gene dosage. We found that both alterations enhanced the degradation of the PS-2 full-length protein, indicating that they may have a loss-of function effect. The effect of the R71W alteration was noticeably stronger, and we observed an almost threefold higher frequency of this allele in breast cancer cases versus controls, but this difference did not reach statistical significance. Nonetheless, these results collectively suggest that the novel PS-2 alleles described here, especially R71W, affect PS-2 function and may potentially confer a moderate risk of susceptibility to breast cancer.

ADH3 genotype, alcohol intake and breast cancer risk

Moderate alcohol consumption of approximately 1-2 drinks per day has been associated with a 30-50% increase in breast cancer risk. Individuals differ in their ability to metabolize alcohol through genetic differences in alcohol dehydrogenase (ADH), the enzyme that catalyzes the oxidation of approximately 80% of ethanol to acetaldehyde, a known carcinogen. Individuals differ in their ADH genotype, and one locus in particular (ADH3) is polymorphic in Caucasian populations. Using data from the Long Island Breast Cancer Study Project, we examined whether fast metabolizers of alcohol, as measured by the ADH3(1-1) genotype, have a higher risk of breast cancer from alcohol intake compared with those individuals who are slow metabolizers, but consume similar amounts of alcohol. We combined genotyping information with questionnaire data on 1047 breast cancer cases and 1101 controls and used unconditional logistic regression methods to estimate multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) between alcohol intake and breast cancer risk. Among individuals homozygous for the fast metabolizing allele (ADH(3)1-1), a lifetime alcohol consumption of 15-30 g/day (approximately 1-2 drinks per day) increased breast cancer risk by 2-fold (OR=2.0, 95% CI=1.1-3.5). In contrast, the increase in risk from a lifetime alcohol consumption of 15-30 g/day was less pronounced in the intermediate and slow metabolizing groups, respectively: ADH3(1-2) (OR=1.5, 95% CI 0.9-2.4) and ADH(3)2-2 (OR=1.3, 95% CI 0.5-3.5). Fast metabolizers who drank 15-30 g/day of alcohol had 2.3 times (95% CI 1.3-4.0) greater risk of breast cancer than non-drinkers who were intermediate or slow metabolizers. This association for fast metabolizers who drank 15-30 g/day was particularly pronounced among premenopausal women (premenopausal women OR=2.9, 95 % CI=1.2-7.1; postmenopausal women OR=1.8, 95% CI=0.9-3.8). These population-based data support the hypothesis that fast metabolizers of alcohol have a higher risk of breast cancer risk, from alcohol intake than slow metabolizers.

Light and exercise and melatonin production in women

Melatonin may protect against breast cancer. Light and other factors influence melatonin, but the evidence is limited. The authors conducted a study to determine factors related to melatonin. Women volunteers recruited in Toronto, Canada, from 2002 to 2004 collected urine for three nights (winter and summer), took periodic light measurements, and recorded exposures in a diary. The relation of each variable to log-transformed creatinine-corrected 6-sulfatoxymelatonin in overnight urine was determined by use of generalized estimating equation linear regression. The final model was based on 1,054 measurement days from 213 participating women. None of the light variables was related to the log of 6-sulfatoxymelatonin. A significant interaction between season and day length was included in the final model. The most significant factor was duration of exercise (beta = 0.072; p = 0.004, two-tailed), which increased the amount of melatonin produced. Exercise duration later in the day was more significant (beta = 0.108; p = 0.0009, two-tailed). There was no difference between moderate or strenuous exercise. The failure to find a relation between light brightness and melatonin may be due to the difficulty of measuring this, as well as the importance of the light spectrum, which could not be measured. It is possible that the protective effect of exercise with respect to breast cancer may operate in part through an effect on melatonin.