Common ERBB2 polymorphisms and risk of breast cancer in a white British population: a case-control study

IntroductionAbout two-thirds of the excess familial risk associated with breast cancer is still unaccounted for and may be explained by multiple weakly predisposing alleles. A gene thought to be involved in low-level predisposition to the disease is ERBB2 (HER2). This gene is involved in cell division, differentiation, and apoptosis and is frequently amplified in breast tumours. Its amplification correlates with poor prognosis. Moreover, the coding polymorphism I655V has previously been associated with an increased risk of breast cancer.MethodsWe aimed to determine if common polymorphisms (frequency ≥ 5%) in ERBB2 were associated with breast cancer risk in a white British population. Five single-nucleotide polymorphisms (SNPs) were selected for study: SNP 1 near the promoter, SNP 2 in intron 1, SNP 3 in intron 4, SNP 4 in exon 17 (I655V), and SNP 5 in exon 27 (A1170P). We tested their association with breast cancer in a large case–control study (n = 2192 cases and 2257 controls).ResultsThere were no differences in genotype frequencies between cases and controls for any of the SNPs examined. To investigate the possibility that a common polymorphism not included in our study might be involved in breast cancer predisposition, we also constructed multilocus haplotypes. Our set of SNPs generated all existing (n = 6) common haplotypes and no differences were seen in haplotype frequencies between cases and controls (P = 0.44).ConclusionsIn our population, common ERBB2 polymorphisms are not involved in predisposition to breast cancer.     

Association of polymorphisms in base excision repair genes with the risk of breast cancer: a case-control study in North Indian women

Inheritance of common genetic variants at one or more base excision repair (BER) genes may result in a reduced DNA repair capacity and in an increased risk of cancers like breast cancer. The present case-control study with 390 north Indian women (155 breast cancer cases and 235 controls) was aimed to investigate the association of seven nonsynonymous BER gene polymorphisms viz. rs1130409/T1865G (APEX1), rs1799782/T22142C (XRCC1), rs25487/G23990A (XRCC1), rs4989588/T3337A (FEN1), rs4989586/ G3259A (FEN1), rs4989587/C3315T (FEN1), and rs1050525/G6941T (PCNA) with breast cancer susceptibility. Statistically significant association with breast cancer risk was observed for rs1130409 homozygous mutant GG [odds ratio (OR) 3.35, 95% confidence interval (CI) 1.36-8.26), heterozygous GT (OR 2.42, 95% CI 1.56-3.76), and combined mutant (GT + GG) (OR 2.52, 95% CI 1.65-3.86] genotypes and rs25487 homozygous mutant AA (OR 2.91, 95% CI 1.66-5.10) and combined mutant (AA + AG) (OR 1.41, 95% CI 0.903-2.19) genotypes, whereas protective association was exhibited by rs1799782 homozygous mutant CC (OR 0.413, 95% CI 0.082-2.08), heterozygous TC (OR 0.351, 95% CI 0.189-0.650), and combined mutant (TC + CC) (OR 0.357, 95% CI 0.199-0.641) genotypes. Association study using reconstructed haplotypes of XRCC1 gene showed positive association for the TA haplotype (OR 2.014, 95% CI 1.462-2.775) and a protective association for the CG haplotype (OR 0.173, 95% CI 0.052-0.576) pertaining to breast cancer risk. The results indicate that the polymorphisms rs1130409 (APEX1) and rs25487 (XRCC1) might be involved in contributing towards breast cancer susceptibility, while rs1799782 (XRCC1) might have protective influence.     

A PALB2 mutation associated with high risk of breast cancer

Introduction

As a group, women who carry germline mutations in partner and localizer of breast cancer 2 susceptibility protein (PALB2) are at increased risk of breast cancer. Little is known about by how much or whether risk differs by mutation or family history, owing to the paucity of studies of cases unselected for family history.

Methods

We screened 1,403 case probands for PALB2 mutations in a population-based study of Australian women with invasive breast cancer stratified by age at onset. The age-specific risk of breast cancer was estimated from the cancer histories of first- and second-degree relatives of mutation-carrying probands using a modified segregation analysis that included a polygenic modifier and was conditioned on the carrier case proband. Further screening for PALB2 c.3113G > A (W1038X) was conducted for 779 families with multiple cases of breast cancer ascertained through family cancer clinics in Australia and New Zealand and 764 population-based controls.

Results

We found five independent case probands in the population-based sample with the protein-truncating mutation PALB2 c.3113G > A (W1038X); 2 of 695 were diagnosed before age 40 years and 3 of 708 were diagnosed when between ages 40 and 59 years. Both of the two early-onset carrier case probands had very strong family histories of breast cancer. Further testing found that the mutation segregated with breast cancer in these families. No c.3113G > A (W1038X) carriers were found in 764 population-based unaffected controls. The hazard ratio was estimated to be 30.1 (95% confidence interval (CI), 7.5 to 120; P < 0.0001), and the corresponding cumulative risk estimates were 49% (95% CI, 15 to 93) to age 50 and 91% (95% CI, 44 to 100) to age 70. We found another eight families carrying this mutation in 779 families with multiple cases of breast cancer ascertained through family cancer clinics.

Conclusions

The PALB2 c.3113G > A mutation appears to be associated with substantial risks of breast cancer that are of clinical relevance.     

Association of two CASP8 polymorphisms with breast cancer risk: a meta-analysis

Caspase-8 (CASP8) is an initiator caspase implicated in the process of apoptosis in breast cancer cells. Attention has been drawn upon two polymorphisms: CASP8 D302H (rs1045485) and, more recently, CASP8 −652 6N del (rs3834129). The CASP8 −652 6N del polymorphism remains an open field, as studies are controversial. This meta-analysis aims to examine: (i) the association between CASP8 −652 6N del and breast cancer risk, separately in Chinese and Caucasian populations, and (ii) the association between CASP8 D302H and breast cancer risk. Eligible articles were identified by a search of MEDLINE, Cochrane, and EMBASE bibliographical databases for the period from June 1996 to July 2009. Regarding −652 6N del, five case–control studies were eligible (12,439 breast cancer cases, 13,253 controls) and four case–control studies were eligible for D302H (18,791 breast cancer cases, 20,318 controls). In case significant heterogeneity was detected, the random effects model was chosen; nevertheless, the fixed effects estimates are also secondarily reported as an alternative approach. Where appropriate, power calculations were performed. CASP8 −652 6N del was associated with reduced breast cancer risk at a borderline level (for del carriers: pooled OR = 0.884, 95% CI: 0.761–1.028); the power calculation pointed to lack of power in the individual studies. In the Caucasian populations, the same results seem valid (for del carriers: pooled OR = 0.944, 95% CI: 0.884–1.008). The random effects model in Chinese subjects has not reached statistical significance (for del carriers: pooled OR = 0.811, 95% CI: 0.492–1.338). CASP8 D302H was associated with reduced breast cancer risk (for H carriers: pooled OR = 0.874, 95% CI: 0.834–0.917). In conclusion, both CASP8 −652 6N del and D302H polymorphisms are associated with reduced cancer risk. Further studies are needed to gain the optimal power on −652 6N del, especially in Chinese subjects, as well as to gain insight into D302H in Chinese populations.     

Association between glutathione S-transferase p1 polymorphisms and lung cancer risk in Caucasians: a case-control study

Glutathione transferases (GSTs), a multiple gene family of phase II enzymes, catalyze detoxifying endogenous reactions with glutathione and protect cellular macromolecules from damage caused by cytotoxic and carcinogenic agents. Glutathione S-transferase p1 (GSTP1), the most abundant GST isoform in the lung, metabolizes numerous carcinogenic compounds including benzo[a]pyrene, a tobacco carcinogen. Previous studies suggest that genetic polymorphisms of GSTP1 exon 5 (Ile105Val) and exon 6 (Ala114Val) have functional effects on the GST gene product resulting in reduced enzyme activity. Individuals with reduced GST enzymatic activity may be at a greater risk for cancer due to decreased detoxification of carcinogenic and mutagenic compounds. Utilizing a hospital-based case-control study, we investigated the association between GSTP1 polymorphisms at exons 5 and 6 with lung cancer risk. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used to successfully genotype the GSTP1 exons 5 and 6 polymorphism in 582 Caucasian lung cancer cases and 600 frequency matched Caucasian controls. There was no association between the exon 5 variant genotypes (A/G+G/G) and overall lung cancer risk (OR=1.09; 95% CI 0.82-1.45) nor when stratified by age, gender, and smoking status. However, the exon 6 variant genotypes (C/T+T/T) were associated with a statistically significant elevated lung cancer risk (OR=1.40; 95% CI 1.06-1.92). Additionally, there was an increase in lung cancer risk for the exon 6 variant genotypes in younger individuals (<62 years) (OR=1.63; 95% C.I. 1.07-2.49) but no effect in older individuals (OR=1.14; 95% CI 0.72-1.81). A statistically significant increased risk of lung cancer was also observed for the exon 6 variant genotypes among men (OR=2.17; 95% CI 1.41-3.33), but not among women (OR=0.80; 95% CI 0.51-1.28). Among ever smokers, the exon 6 variant genotypes were associated with an elevated lung cancer risk (OR=1.58; 95% CI 1.14-2.19), which was not evident for never smokers (OR=0.53; 95% CI 0.21-1.33). These data demonstrate that the GSTP1 exon 6 polymorphism, but not the exon 5 polymorphism, is associated with lung cancer risk that is especially evident in men, younger individuals, and ever smokers.     

Association of polymorphisms in one-carbon metabolizing genes and lung cancer risk: a case-control study in Chinese population

One-carbon metabolism facilitates the cross-talk between genetic and epigenetic processes, making it a good candidate for studying the risk of lung cancer. To investigate the role of common variants of one-carbon metabolizing genes on lung cancer risk, total 25 single nucleotide polymorphisms (SNPs) in 7 genes were genotyped among 500 incident lung cancer patients and 517 cancer-free controls. An increased risk was suggested for the variant allele carriers of MTHFR rs17037396 [odds ratio (OR)=1.39, 95% confidence interval (CI): 1.00-1.94] and rs3753584 (OR=1.46, 95% CI: 1.03-2.08), compared with subjects with wild homozygote, respectively, and the risk was more pronounced among older individuals (>60 years). In contrast, a decreased risk was observed for TYMS rs2853742 variant allele carriers (OR=0.44, 95% CI: 0.19-0.99) and MTHFD rs2236225 variant allele carriers (OR=0.76, 95% CI: 0.59-0.99). Haplotype analysis revealed that MTHFR "ACCACC" haplotype may contribute to the risk of lung cancer (OR=1.49, 95% CI: 1.03-2.14, local test p value 0.032). A data mining method, multifactor dimensionality reduction (MDR), predicted a four-factor interaction model (rs1801133, rs4659731, rs2273029 and rs699517) with the lowest average prediction error (45.08%, p<0.001). These findings suggest that genetic variants in one-carbon metabolizing genes might modulate the risk of lung cancer. Validation of these findings in larger studies is needed.     

Association of a common AKAP9 variant with breast cancer risk: a collaborative analysis

Data from several studies have suggested that polymorphisms in A-kinase anchoring proteins (AKAPs), which are key components of signal transduction, contribute to carcinogenesis. To evaluate the impact of AKAP variants on breast cancer risk, we genotyped six nonsynonymous single-nucleotide polymorphisms that were predicted to be deleterious and found two (M463I, 1389G>T and N2792S, 8375A>G) to be associated with an allele dose-dependent increase in risk of familial breast cancer in a German population. We extended the analysis of AKAP9 M463I, which is in strong linkage disequilibrium with AKAP9 N2792S, to 9523 breast cancer patients and 13770 healthy control subjects from seven independent European and Australian breast cancer studies. All statistical tests were two-sided. The collaborative analysis confirmed the association of M463I with increased breast cancer risk. Among all breast cancer patients, the combined adjusted odds ratio (OR) of breast cancer for individuals homozygous for the rare allele TT (frequency = 0.19) compared with GG homozygotes was 1.17 (95% confidence interval [CI] = 1.08 to 1.27, P = .0003), and the OR for TT homozygotes plus GT heterozygotes compared with GG homozygotes was 1.10 (95% CI = 1.04 to 1.17, P = .001). Among the combined subset of 2795 familial breast cancer patients, the respective ORs were 1.27 (95% CI = 1.12 to 1.45, P = .0003) and 1.16 (95% CI = 1.06 to 1.27, P = .001).     

Lactation and breast cancer risk: a case-control study in Connecticut

In this report, we examined the relationship between lactation and breast cancer risk, in a case-control study of breast cancer, conducted in Connecticut between 1994 and 1998. Included were 608 incident breast cancer cases and 609 age frequency matched controls, aged 30-80 years old. Cases and controls were interviewed by trained study interviewers, using a standardized, structured questionnaire, to obtain information on lactation and other major risk factors. Parous women who reported ever lactation had a borderline significantly reduced risk of breast cancer (OR = 0.83, 95% CI, 0.63-1.09). An OR of 0.53 (95% CI, 0.27-1.04) was observed in those having breastfed more than 3 children compared to those who never lactated. Women having breastfed their first child for more than 13 months had an OR of 0.47 (95% CI, 0.23-0.94) compared to those who never breastfed. Lifetime duration of lactation also showed a risk reduction while none of the ORs were statistically significant. Further stratification by menopausal status showed a risk reduction related to lactation for both pre- and postmenopausal women, while the relationship is less consistent for the latter. These results support an inverse association between breastfeeding and breast cancer risk.     

Genetic polymorphisms in the one-carbon metabolism pathway and breast cancer risk: a population-based case-control study and meta-analyses

Epidemiological evidence suggests that intake of folate and other B-vitamins and genetic variants in the one-carbon metabolism pathway could influence the risk of breast cancer. Previous studies have focused on 2 polymorphisms in the methylenetetrahydrofolate gene (MTHFR A222V and E429A); however, findings are inconclusive. In a large population-based case-control study in Poland (2,386 cases, 2,502 controls), we investigated the association between breast cancer risk and 13 polymorphisms in 6 one-carbon metabolism genes (MTHFR, MTR, MTRR, CBS, SHMT1 and SLC19A1). Data suggested an association between a nonsynonymous change in the gene coding for methionine synthase (MTR D919G) and reduced breast cancer risk: OR (95% CI) = 0.84 (0.73-0.96) and 0.85 (0.62-1.15) for heterozygous and homozygote variant genotypes, respectively, compared with common homozygotes; p-trend = 0.01, false discovery rate = 0.14. We found no significant associations between other variants and breast cancer risk, including MTHFR A222V or E429A. Meta-analyses including published studies of MTHFR A222V (8,330 cases and 10,825 controls) and E429A (6,521 cases and 8,515 controls) supported the lack of an overall association; however, studies suggested an increase in risk among premenopausal women. In conclusion, this report does not support a substantial overall association between the evaluated polymorphisms in the one-carbon metabolism pathway and breast cancer risk.     

Five common single nucleotide polymorphisms in the PALB2 gene and susceptibility to breast cancer in eastern Chinese population

Certain rare germline mutations in the PALB2 gene have been confirmed to increase susceptibility to breast cancer in diverse populations, but it has not been very clear that whether some common polymorphic variants in PALB2 also increase breast cancer risk. We conducted a case–control study to validate the association of common variations in the PALB2 gene and breast cancer in eastern Chinese population. A total of six common single nucleotide polymorphisms (rs8053188, rs16940342, rs249954, rs447529, rs249935, and rs3096145), which tagged the known common variants (minor allele frequency >0.1) of PALB2, were genotyped among 660 cases and 756 cancer-free controls by SNPstream assay. Except rs3096145, other five SNPs passed the quality assessment criteria with genotyping call rate >95%. Genotype and allele frequencies were statistically different between cases and controls for PALB2 rs447529 and rs249935. PALB2 rs249935 G allele was related to a 1.21-fold (95% confidence interval = 1.02–1.43) increase in risk for each ‘A’ allele carried (P = 0.029). Based on the dominant inheritance model tests, we found that compared with rs447529 CC homozygotes, the variant homozygote GG and heterozygote GC carriers had a 0.43-fold decreased risk of breast cancer (95% confidence interval = 0.24–0.78, P = 0.005). Combined with the results of the former study, our findings further verified that some common PALB2 polymorphisms may contribute to the etiology of breast cancer in Chinese women, so other large studies are warranted to confirm these observations in different ethnic populations.     

Vitamin D pathway gene polymorphisms,diet, and risk of postmenopausal breast cancer: a nested case-control study

Introduction  

Vitamin D receptor (VDR) polymorphisms have been inconsistently associated with breast cancer risk. Whether risk is influenced by polymorphisms in other vitamin D metabolism genes and whether calcium or vitamin D intake modifies risk by genotype have not been evaluated.     

Premenopausal serum androgens and breast cancer risk: a nested case-control study

Introduction

Prospective epidemiologic studies have consistently shown that levels of circulating androgens in postmenopausal women are positively associated with breast cancer risk. However, data in premenopausal women are limited.

Methods

A case-control study nested within the New York University Women's Health Study was conducted. A total of 356 cases (276 invasive and 80 in situ) and 683 individually-matched controls were included. Matching variables included age and date, phase, and day of menstrual cycle at blood donation. Testosterone, androstenedione, dehydroandrosterone sulfate (DHEAS) and sex hormone-binding globulin (SHBG) were measured using direct immunoassays. Free testosterone was calculated.

Results

Premenopausal serum testosterone and free testosterone concentrations were positively associated with breast cancer risk. In models adjusted for known risk factors of breast cancer, the odds ratios for increasing quintiles of testosterone were 1.0 (reference), 1.5 (95% confidence interval (CI), 0.9 to 2.3), 1.2 (95% CI, 0.7 to 1.9), 1.4 (95% CI, 0.9 to 2.3) and 1.8 (95% CI, 1.1 to 2.9; P _trend = 0.04), and for free testosterone were 1.0 (reference), 1.2 (95% CI, 0.7 to 1.8), 1.5 (95% CI, 0.9 to 2.3), 1.5 (95% CI, 0.9 to 2.3), and 1.8 (95% CI, 1.1 to 2.8, P _trend = 0.01). A marginally significant positive association was observed with androstenedione (P = 0.07), but no association with DHEAS or SHBG. Results were consistent in analyses stratified by tumor type (invasive, in situ), estrogen receptor status, age at blood donation, and menopausal status at diagnosis. Intra-class correlation coefficients for samples collected from 0.8 to 5.3 years apart (median 2 years) in 138 cases and 268 controls were greater than 0.7 for all biomarkers except for androstenedione (0.57 in controls).

Conclusions

Premenopausal concentrations of testosterone and free testosterone are associated with breast cancer risk. Testosterone and free testosterone measurements are also highly reliable (that is, a single measurement is reflective of a woman's average level over time). Results from other prospective studies are consistent with our results. The impact of including testosterone or free testosterone in breast cancer risk prediction models for women between the ages of 40 and 50 years should be assessed. Improving risk prediction models for this age group could help decision making regarding both screening and chemoprevention of breast cancer.     

Population-based case-control study of VEGF gene polymorphisms and breast cancer risk among Chinese women.

Vascular endothelial growth factor (VEGF) is a major angiogenic factor involved in a number of pathologic processes, including neovascularization, a crucial step in the development of solid malignancies. Using data and specimens collected in the Shanghai Breast Cancer Study, a population-based case-control study conducted in urban Shanghai, China from 1996 to 1998, we evaluated the association of VEGF gene polymorphisms with breast cancer risk. Included in this study were 1,093 cases and 1,184 age-matched controls who had completed an in-person interview and donated a blood sample to the study. Polymorphisms in the promoter region (T -460C), 5' untranslated region (C +405G), and 3'untranslated region (C936T) were genotyped using the Taqman allelic discrimination assay. No statistically significant case-control difference was found for the C +405G and T -460C polymorphisms. However, the C936T polymorphism was associated with a reduced risk of breast cancer. Compared with CC genotype carriers, women who had the TT genotype showed a decreased risk [odds ratio (OR), 0.65; 95% confidence interval (95% CI) 0.41-1.02], and the inverse association was restricted to premenopausal women (OR, 0.45; 95% CI, 0.25-0.79). Six common haplotypes were identified. Compared with the most common haplotype (-460T/405C/936C), the -460T/405G/936T haplotype was associated with a reduced risk of breast cancer (OR, 0.67; 95% CI, 0.43-1.04), particularly in premenopausal women (OR, 0.47; 95% CI, 0.27-0.81). Our study suggests that the VEGF C936T polymorphism might be a susceptibility factor for breast cancer among Chinese women.     

XRCC1 and XPD genetic polymorphisms, smoking and breast cancer risk in a Finnish case-control study

Introduction

It has been suggested that individuals with reduced DNA repair capacities might have increased susceptibility to environmentally induced cancer. In this study, we evaluated if polymorphisms in DNA repair genes XRCC1 (Arg280His, Arg399Gln) and XPD (Lys751Gln) modify individual breast cancer risk, with emphasis on tobacco smoking.

Methods

The study population consisted of 483 incident breast cancer cases and 482 population controls of Finnish Caucasian origin. The genotypes were determined by PCR-RFLP-based methods. Odds ratio (OR) and confidence intervals (CIs) were calculated by unconditional logistic regression analyses.

Results

No statistically significant overall effect in the breast cancer risk was seen for any of the studied polymorphisms. However, a significant increase in breast cancer risk was seen among ever smoking women if they carried at least one XRCC1-399 Gln allele (OR 2.33, 95% CI 1.30–4.19, p _int 0.025) or XPD-751 Gln/Gln genotype (OR 2.52, 95% CI 1.27–5.03, p _int 0.011) compared to smoking women not carrying these genotypes. The risks were found to be confined to women smoking at least five pack-years; the respective ORs were 4.14 (95% CI 1.66–10.3) and 4.41 (95% CI 1.62–12.0). Moreover, a significant trend of increasing risk with increasing number of the putative at-risk genotypes (p for trend 0.042) was seen. Women with at least two at-risk genotypes had an OR of 1.54 (95% CI 1.00–2.41) compared to women with no at-risk genotypes. Even higher estimates were seen for ever actively smoking women with at least two at-risk genotypes.

Conclusion

Our results do not indicate a major role for XRCC1 and XPD polymorphisms in breast cancer susceptibility, but suggest that they may modify the risk especially among smoking women.     

Association between WT1 polymorphisms and susceptibility to breast cancer: results from a case-control study in a southwestern Chinese population

Wilms’ tumor gene 1 (WT1) single nucleotide polymorphism (SNP), rs16754, has been considered as an independent prognostic factor in patients with acute myeloid leukemia and renal cell carcinoma. However, its biological role in breast cancer has not been reported. To test whether WT1 SNPs can be used as a molecular marker in order to improve the risk stratification of breast cancer, we performed a case-control study including 709 female sporadic breast cancer patients and 749 female healthy control subjects in the Southeast China. Five WT1 SNPs (rs16754, rs3930513, rs5030141, rs5030317, rs5030320) were selected and determined by polymerase chain reaction-ligase detection reaction to assess their associations with breast cancer risk. Results showed the distributions of the alleles of these WT1 SNPs were consistent with data from Chinese population as suggested by the International HapMap Project. Individuals with the minor alleles of rs16754, rs5030317 and rs5030320 showed a significant decrease of breast cancer risk in codominant model (OR = 0.6370, 95% CI: 0.4260-0.9520 for rs16754; OR = 0.5940, 95% CI: 0.3890-0.9070 for rs5030317; OR = 0.5870, 95% CI: 0.3850-0.8960 for 5030320, respectively) and recessive model. Stratified analyses showed the protective effects were more evident in the subjects with age ≤ 50 years or in pre-menopausal status. To explore the potential mechanism, we conducted bioinformatics genotype-phenotype correlation analysis, and found that the mRNA expression level for homozygous rare allele of WT1 gene was lower than that in wild-type and heterozygous group (P = 0.0021) in Chinese population. In summary, our findings indicated that minor alleles of rs16754, rs5030317 and rs5030320 are associated with reduced risk of breast cancer, suggesting that WT1 SNPs may be a potential biomarker of individualized prediction of susceptibility to breast cancer. However, large prospective and molecular epidemiology studies are needed to verify this correlation and clarify its underlying mechanisms.     

Interaction of dense breast patterns with other breast cancer risk factors in a case-control study

The question of interactions between breast density and other breast cancer risk factors is of interest, since it bears upon the use of density as a marker for changes in breast cancer risk. We studied breast parenchymal patterns and 13 other potential risk factors for breast cancer in 172 breast cancer cases and 338 age-matched controls in Singapore. Dense breast patterns were defined as having Tabar parenchymal pattern IV or V. We found significant interactions between dense patterns and ethnic group (P=0.046), and between dense patterns and number of deliveries (P=0.04). Among women with nondense breast patterns, the non-Chinese had lower risk than the Chinese with an odds ratio (OR) of 0.47 (95% CI 0.24, 0.88), whereas in those with dense patterns, the non-Chinese had considerably higher risks (OR=5.34, 95% CI 0.54, 52.51). Alternatively expressed, the increased risk with dense patterns was only observed in the non-Chinese (OR=13.99, 95% CI 1.33, 146.99). Among parous women, the protective effect of three or more deliveries was only observed in those with dense breast patterns (OR=0.21, 95% CI 0.06, 0.70). Suggestive but nonsignificant interactions with dense patterns were observed for ever having delivered, age at first delivery, breast feeding and body mass index. The results are consistent with dense breast patterns as a marker for hormonal modification of breast cancer risk.