Association of cardiometabolic comorbidities with mortality among low-income Black and White Americans

METHODS

Investigated the association of multiple cardiometabolic comorbidities with total/major cause-specific mortality and evaluate if this association might be modified by race among predominantly low-income Black and White participants.

METHODS

The Southern Community Cohort Study, prospective cohort study. Participants (40-79 years) recruited predominantly from community health centers across 12 states in southeastern United States. Enrollment began in 2002 and concluded in 2009, follow-up until 2020. Cardiometabolic comorbidities (diabetes, hypertension, myocardial infarction, stroke) ascertained at the baseline survey. Cox proportional hazard models used.

RESULTS

Study included 76,721 participants; 16,197, 41,944, 5,247, and 4,919 participants with prior diagnosis of diabetes, hypertension, myocardial infarction, and stroke, respectively at baseline. Compared to individuals with no comorbidity, individuals with any single comorbidity experienced a significantly 30 to 90% increased rate of death due to any causes. The increase in mortality was elevated with an increasing number of comorbidities, with HR of 3.81 (95% CI: 3.26-4.46) and a cumulative risk of 62.5% at age 75 years for total mortality for those with four comorbidities. The risk was high for death due to cardiovascular diseases (HR: 6.18, 95% CI: 5.12-7.47). These associations were stronger among Blacks than Whites. Individuals with four comorbidities at age 40 years were estimated to have a 16-year loss in life expectancy compared with those without any comorbidity.

CONCLUSION

Cardiometabolic comorbidities were associated with increases in all-cause and major cause-specific mortality, particularly Black Americans. This study calls for effective measures to prevent cardiometabolic comorbidities to reduce premature deaths in underserved Americans.

Abstract P215: Inflammatory and Insulinemic Dietary Patterns Are Associated With Modestly Increased Total and Cardiometabolic Mortality Among Low-Income Americans

Introduction: Diet is a modifiable risk factor for cardiometabolic morbidity and mortality, potentially via increased inflammation. Two hypothesis-oriented dietary patterns, the empirical dietary inflammatory potential (EDIP) and empirical dietary index for hyperinsulinemia (EDIH), have been linked to increased risk of cardiometabolic diseases and overall mortality. However, their associations with total and cause-specific mortality in Black Americans and populations of low socioeconomic status (SES) have not been described.

Hypothesis: We assessed the hypothesis that higher EDIP and EDIH scores are associated with increased total and cause-specific mortality in a low SES and predominately Black population.

Methods: In the Southern Community Cohort Study, a prospective cohort of mostly low-income Black and White adults recruited from 12 Southeastern states in the US, we included 77,209 participants who completed a food frequency questionnaire (FFQ) at baseline (2002-2009) and had been followed-up for mortality outcomes through 2019. The EDIP and EDIH scores were estimated based on 18 components derived from the FFQ. Cox proportional hazard models were used to estimate hazard ratios (HRs) of total and cardiometabolic mortality for the highest vs. lowest quintiles (Q5 vs. Q1) of EDIP/EDIH, adjusting for sociodemographics, lifestyles, and history of major chronic diseases. In a subgroup of 5,162 participants with data on blood levels of high-sensitivity C-reactive protein (hs-CRP), we also evaluated the correlations of EDIP and EDIH with hs-CRP.

Results: Of 77,209 participants, 46,233 (59.9%) were women, 49,925 were Black (64.7%), and mean age was 52.4 (SD: 8.8) years at baseline. During an average follow-up of 12.9 years, we documented 20,028 total deaths, including 6,296 from cardiovascular disease and 1,150 from diabetes. Higher EDIP and EDIH scores were both associated with increased total and cardiometabolic mortality. EDIP and EDIH Q5 vs. Q1 HRs were 1.10 and 1.11 for total mortality, respectively (95% CIs: 1.05-1.16 and 1.06-1.17), 1.20 and 1.15 for cardiovascular mortality, respectively (95% CIs: 1.11-1.31 and 1.06-1.25), and 1.38 and 1.34 for diabetes mortality, respectively (95% CIs: 1.13-1.67 and 1.10-1.63); all p-trend ≤0.001. EDIP and EDIH weakly correlated with hs-CRP, despite statistical significance (r=0.058 for EDIP and 0.081 for EDIH; both p<0.0001).

Conclusions: In conclusion, empirical inflammatory and insulinemic dietary patterns are associated with modestly increased inflammation and total and cardiometabolic mortality among low-income Black and White Americans. Efforts to improve nutrition may improve overall cardiometabolic health and prognosis.

Investigation of Novel Urinary Biomarkers in Hepatocellular Carcinoma Risk in a Predominantly African American Population: A Case-Control Study

Introduction

African Americans are at increased risk of hepatocellular carcinoma (HCC) compared to other racial and ethnic groups. We investigated the associations of four urinary biomarkers of prostaglandin E2 (PGE-M), prostacyclin (PGI-M), and thromboxane (11dTxB2) synthesis and the ratio of PGI-M to 11dTXB2 with HCC risk in a cohort of predominantly African American populations.

Methods

We conducted a nested case-control study (50 cases; 43 with HCC, 151 controls) in the Southern Community Cohort Study (SCCS), a large prospective cohort study including over 80,000 study participants, of whom two-thirds are African Americans. Urine samples were collected at enrollment and subsequently analyzed to assess biomarker levels. Multivariable regression models adjusted for age, race, sex, BMI, smoking status, NSAID use, education level, income, and alcohol consumption were used to assess the relationship between the biomarker and HCC risk.

Results

Only 11dTxB2 (OR = 11.50; 95% CI [2.34-56.47] for highest tertile vs. lowest tertile, p = 0.004) and the PGI-M/11dTXB2 ratio of the second quartile (0.25-0.49) (OR = 5.16; 95% CI [1.44-18.47]; p = 0.01) were significantly associated with increased risk of liver cancer.

Conclusion

11dTXB2 and PGI-M/11dTXB2 ratio may be urinary markers of HCC risk, particularly among African Americans, and future prospective studies are needed to evaluate this finding further and to develop accessible methods.

Association of Healthy Lifestyles With Risk of Alzheimer Disease and Related Dementias in Low-Income Black and White Americans

BACKGROUND AND OBJECTIVES

Although the importance of healthy lifestyles for preventing Alzheimer disease and related dementias (ADRD) has been recognized, epidemiologic evidence remains limited for non-White or low-income individuals who bear disproportionate burdens of ADRD. This population-based cohort study aims to investigate associations of lifestyle factors, individually and together, with the risk of ADRD among socioeconomically disadvantaged Americans.

METHODS

In the Southern Community Cohort Study, comprising two-thirds self-reported Black and primarily low-income Americans, we identified incident ADRD using claims data among participants enrolled in Medicare for at least 12 consecutive months after age 65 years. Five lifestyle factors-tobacco smoking, alcohol consumption, leisure-time physical activity (LTPA), sleep hours, and diet quality-were each scored 0 (unhealthy), 1 (intermediate), or 2 (healthy) based on the health guidelines. A composite lifestyle score was created by summing all scores. Cox regression was used to estimate hazard ratios (HRs, 95% CIs) for incident ADRD, treating death as a competing risk.

RESULTS

We identified 1,694 patients with newly diagnosed ADRD among 17,209 participants during a median follow-up of 4.0 years in claims data; the mean age at ADRD diagnosis was 74.0 years. Healthy lifestyles were individually associated with an 11%-25% reduced risk of ADRD: multivariable-adjusted HR (95% CI) was 0.87 (0.76-0.99) for never vs current smoking, 0.81 (0.72-0.92) for low-to-moderate vs no alcohol consumption, 0.89 (0.77-1.03) for ≥150 minutes of moderate or ≥75 minutes of vigorous LTPA each week vs none, 0.75 (0.64-0.87) for 7-9 hours vs >9 hours of sleep, and 0.85 (0.75-0.96) for the highest vs lowest tertiles of the Healthy Eating Index. The composite lifestyle score showed a dose-response association with up to 36% reduced risk of ADRD: multivariable-adjusted HRs (95% CIs) across quartiles were 1 (ref), 0.88 (0.77-0.99), 0.79 (0.70-0.90), and 0.64 (0.55-0.74); p trend <0.001. The beneficial associations were observed regardless of participants' sociodemographics (e.g., race, education, and income) and health conditions (e.g., history of cardiometabolic diseases and depression).

DISCUSSION

Our findings support significant benefits of healthy lifestyles for ADRD prevention among socioeconomically disadvantaged Americans, suggesting that promoting healthy lifestyles and reducing barriers to lifestyle changes are crucial to tackling the growing burden and disparities posed by ADRD.

Abstract 5894: Synergism between medium-chain fatty acid intake and global magnesium status on the risk of cancer mortality in the National Health and Nutrition Examination Survey (NHANES) 2005-2014

Medium-chain fatty acids (MCFAs), a class of saturated fatty acids that exist naturally in dairy products and tropical oils, can regulate inflammation, insulin resistance, and immune response. Furthermore, in vitro and in vivo studies found MCFAs have strong anticarcinogenic properties. Recent evidence reveals MCFAs inhibits aerobic glycolysis in tumor cells. It is conceivable that MCFAs have an “anti-Warburg effect”. In a double-blind randomized trial (Personalized Prevention of Colorectal Cancer; NCT01105169), we found that 12-week personalized magnesium (Mg) supplementation led to significantly increased circulating levels of MCFAs, particularly caprylic acid (C8:0), which was due to enhanced microbial production. These novel findings suggest individuals with Mg sufficiency can receive supplies of MCFAs from microbiome whereas people with Mg deficiency cannot and so need MCFAs from intake. Thus, we hypothesized that the associations between intakes of C8:0 and risk of cancer mortality are modified by body Mg status. We tested this hypothesis in the NHANES, a nationally representative study. We recently developed the Mg depletion score (MDS) to assess Mg status and validated it against the invasive gold standard measure of Mg status. MDS performs better than either serum Mg or Mg intake at predicting Mg deficiency. We also found higher Mg intake was associated with reduced risks of inflammation and total mortality only among those with higher MDS scores, i.e., higher risk of losing Mg in the kidney. Thus, we examined if MDS modified the associations between intakes of MCFAs and risk of cancer mortality. Among 11,890 US adults aged ≥20 years over a median follow-up of 70 person-months, the associations between C8:0 intake and cancer mortality risk differed by MDS (Pinteraction=0.12). Higher C8:0 intake was associated with increased cancer mortality risk when MDS=0 (no risk of losing Mg; P-trend=0.03) after adjusting for all covariates, including dairy product intake. C8:0 intake was not related to risk of cancer mortality when MDS=1. Conversely, C8:0 intake may be associated with a reduced cancer mortality risk among those with MDS&gt;1(high risk of losing Mg). In particular, higher C8:0 intake was significantly associated with a reduced risk of cancer mortality (P-trend&lt;0.01) with an HR (95% CI) of 0.11 (0.02-0.84) for the highest quartile of C8:0 intake when Mg intake was above the Estimated Average Requirement. No associations were found for intakes of C6:0, C10:0 and C12:0. In summary, C8:0 can be generated by human gut microbiome through optimized Mg consumption; dietary intakes of C8:0 were associated with a reduced risk of cancer mortality among those at high risk of losing Mg, but with adequate Mg consumption; and intakes of C8:0 were related to an increased risk of cancer mortality among those with no risk of losing Mg.

Citation Format: Lei Fan, Xiangzhu Zhu, Alexandra Shingina, Lihua Shu, Martha Shrubsole, Qi Dai. Synergism between medium-chain fatty acid intake and global magnesium status on the risk of cancer mortality in the National Health and Nutrition Examination Survey (NHANES) 2005-2014 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5894.

Healthy Lifestyles and the Risk of Alzheimer's Disease and Related Dementias among Low-Income Black and White Americans

Objectives

While the importance of healthy lifestyles for preventing Alzheimer's disease and related dementias (ADRD) has been recognized, epidemiologic evidence remains limited from non-White or low-income populations who bear disproportionate burdens of ADRD. We examined the associations of major lifestyle factors, individually and together, with incident ADRD in a prospective cohort of primarily low-income Black and White Americans.

Methods

In the Southern Community Cohort Study, incident ADRD were identified using claims data among participants enrolled in Medicare for at least 12 consecutive months after age 65. Five lifestyle factors: tobacco smoking, alcohol consumption, leisure-time physical activity (LTPA), sleep hours, and diet quality, were each scored 0 (unhealthy), 1 (intermediate), or 2 (healthy) based on health guidelines. A composite lifestyle score was created by summing all scores. Cox regression was used to estimate hazard ratios (HRs) and 95% CIs, treating death as a competing risk and adjusting for potential confounders.

Results

Of 17,209 participants, 1,694 incident ADRD were identified during a median 4-year follow-up in claims data; the mean age at ADRD diagnosis was 74.0 years. Healthy lifestyles were individually associated with 11%–25% reduced risk of ADRD: multivariable-adjusted HR (95% CI) was 0.87 (0.76–0.99) for never vs. current smoking, 0.81 (0.72–0.92) for low-to-moderate vs. no alcohol consumption, 0.89 (0.77–1.03) for ≥150 minutes of moderate or ≥75 minutes of vigorous LTPA per week vs. none, 0.75 (0.64–0.87) for 7–9 hours vs. >9 hours of sleep, and 0.85 (0.75–0.96) for the highest vs. lowest tertiles of Healthy Eating Index. The composite lifestyle score showed a dose-response association with up to 36% reduced risk of ADRD: HRs (95% CIs) across quartiles were 1 (ref), 0.88 (0.77–0.99), 0.79 (0.70–0.90), and 0.64 (0.55–0.74); p-trend < 0.001. The beneficial associations were observed regardless of participants’ sociodemographics (e.g., race/ethnicity, education, and income) and health conditions (e.g., history of cardiometabolic diseases and depression).

Conclusions

Our findings support the importance of healthy lifestyles for ADRD prevention among socioeconomically disadvantaged Americans to reduce the growing burden and disparities posted by ADRD.

Funding Sources

The National Institutes of Health.

Dietary Polyphenols and the Risk of Alzheimer's Disease and Related Dementias Among Low-income Black and White Americans

Objectives

To examine the associations of dietary polyphenols and polyphenol-rich foods/beverages with the risk of Alzheimer's disease and related dementias (ADRD) in a multi-ethnic cohort of predominantly low-income Americans.

Methods

In the Southern Community Cohort Study, we estimated intakes of dietary polyphenols, including total, four major classes―flavonoids, phenolic acids, stilbenes, and lignans―and their subclasses, using a validated food frequency questionnaire and polyphenol databases. Incident ADRD was ascertained via Medicare claims data. Cox model was used to estimate hazard ratios (HRs) and 95% CIs, treating death as a competing risk and adjusting for potential confounders. Restricted cubic splines were used to evaluate potential non-linearity of the associations. Analyses were conducted separately among Blacks, Whites, and other ethnicities. Additional subgroup analyses were conducted by income level, educational attainment, and history of cardiometabolic diseases and depression.

Results

Of 14,500 study participants, we identified 1,402 incident ADRD―830 Blacks, 520 Whites, and 52 of other ethnicities―during a median follow-up of 4.0 years in claims data. The median age was 62.0 years at dietary survey and 73.0 years at ADRD diagnosis. The median intake of total dietary polyphenols differed significantly among Blacks (570 mg/d), Whites (1118 mg/d), and other ethnicities (864 mg/d). Total polyphenol intake was not associated with risk of ADRD among all participants or in any racial/ethnic group. However, intakes of flavanols and theaflavins (subclasses of flavonoids) and tea consumption showed significant linear inverse associations among Blacks (HR [95% CI] for highest vs. lowest quartile = 0.72 [0.57–0.91], p-linearity = 0.015; 0.66 [0.53–0.83], p-linearity = 0.006; and 0.69 [0.55–0.86], p-linearity = 0.005, respectively). Meanwhile, a potential non-linear inverse association was suggested for red wine consumption among Whites (HR [95% CI] for highest vs. lowest quartile = 0.69 [0.48–0.99], p-nonlinearity = 0.047). These associations did not differ in additional subgroup analyses.

Conclusions

Our findings indicate beneficial associations of certain dietary polyphenols and polyphenol-rich tea for the prevention of ADRD among low-income Black Americans.

Funding Sources

The National Institutes of Health

1001. Chronic Colonization with Toxigenic Clostridioides difficile Strains Drives Colonic Tumorigenesis in Mice

Background

Long-term effects of chronic and/or recurrent C. difficile infections (CDI) are not well understood, and any potential role of CDI in colorectal cancer (CRC) risk is presently unknown. While pursuing efforts to identify novel procarcinogenic microbes, we identified two mucosal slurries from CRC patients (3728T and 3752T) that were tumorigenic in germ-free (GF) Apc^Min/+ mice. Surprisingly, both of these CRC patient slurries were positive for C. difficile by 16S rRNA amplicon sequencing. Given the ability of other chronic infections to promote tumorigenesis (e.g., H. pylori), we hypothesized that chronic colonization with C. difficile could promote tumorigenesis in the colon.

Methods

A consortium of 30 bacterial isolates including a toxigenic tcdA+ tcdB+ C. difficile strain (CIm_3728T) was cultured from GF Apc^Min/+ mice gavaged with the 3728T slurry. This consortium was gavaged into additional GF Apc^Min/+ mice with or without C. difficile strains CIm_3728T, CIm_3752T (isolated from mice gavaged with the 3752T slurry), or isogenic tcdA/tcdB mutants of the M7404 R027 strain. Single cell RNA sequencing (scRNAseq), high dimensional (HD) flow cytometry, and fluorescence in situ hybridization (FISH) with EUB338 and Cd198 probes were performed on distal colons from mice gavaged with either complex CRC slurries or the 3728T isolates with CIm_3728T.

Results

C. difficile strains drove tumorigenesis of the 3728T isolate mixture (Fig. 1A,B). Tumorigenesis was associated with early procarcinogenic signaling and spatial changes including induction of Wnt signaling in colonic epithelial progenitor cells by scRNAseq, IL-17 induction in immune cells by HD flow cytometry, and bacterial biofilm invasion deep into epithelial crypts by FISH. Tumorigenesis correlated with chronic colonization with toxigenic strains of C. difficile and was toxin-dependent, as toxin mutant strains (M7404 tcdA-tcdB-) did not induce tumors.

Figure 1. C. difficile strains from CRC patients induce distal colonic tumorigenesis in germ-free (GF) ApcMin/+ mice.

A consortium of 30 bacteria, including C. difficile, were isolated from mice gavaged with the 3728T human CRC mucosal slurry. These isolates were then gavaged into additional GF ApcMin/+ mice, with or without C. difficile isolates from mice gavaged with the 3728T slurry or 3752T slurry. (A) Colonic tumor numbers in GF ApcMin/+ mice at 10 wk p.i. demonstrate that C. difficile (Cd) drives the tumorigenesis of this 30-member bacterial consortium. (B) Gross tumors can be observed in the colon of a representative mouse gavaged with the 3728T isolates with the CIm_3728T (top) or CIm_3752T (middle) strain of C. difficile but not in a mouse gavaged with the isolates lacking C. difficile (bottom).

Conclusion

Toxigenic C. difficile strains isolated from human CRC mucosal slurries were pro-carcinogenic in mice, suggesting that C. difficile is a potential driver of CRC. Given the public health burden of C. difficile, further studies are warranted to determine whether C. difficile infections (initial, recurrent, and chronic asymptomatic) increase CRC risk in patients.

Disclosures

Jada Domingue, PhD, AstraZeneca (Employee) James White, PhD, Personal Genome Diagnostics (Consultant) Patricia J. Simner, PhD, Accelerate Diagnostics (Grant/Research Support)Affinity Biosensors (Grant/Research Support)BD Diagnostics (Consultant, Grant/Research Support)GeneCapture (Consultant)OpGen, Inc (Consultant, Grant/Research Support)Shionogi, Inc (Consultant) Karen C. Carroll, MD, MeMed (Scientific Research Study Investigator)Meridian Diagnostics, Inc. (Grant/Research Support)Pattern Diagnostics (Advisor or Review Panel member)Scanogen, Inc. (Advisor or Review Panel member) Karen C. Carroll, MD, Pattern Diagnostics, Inc. (Individual(s) Involved: Self): Grant/Research Support; Scanogen, Inc. (Individual(s) Involved: Self): Consultant Cynthia L. Sears, MD, Bristol Myers Squibb (Grant/Research Support)Ferring (Advisor or Review Panel member)Janssen (Grant/Research Support)

Establishing the Vietnam Center of Research Excellence on Cancer and Other Noncommunicable Diseases (V-CORE): Challenges and Opportunities

PURPOSE

Noncommunicable diseases (NCDs), including cancer, have emerged as a major public health problem in Vietnam; however, NCD research in Vietnam is limited, primarily because of inadequate research infrastructures, funding, and well-trained investigators. To address these challenges, we established a US-Vietnam-China partnership to plan for building the V-CORE (Vietnam Center of Research Excellence on Cancer and Other Noncommunicable Diseases) with the support of a grant from the US National Cancer Institute. The objectives of this program are to assess the need and current NCD research capabilities and infrastructure in Vietnam and to develop and pilot test research capacity building/enrichment programs, including conducting two research projects for demonstration.

METHODS AND RESULTS

Through a need- and capacity-assessment workshop, with participation of stakeholders in NCD research and prevention in Vietnam, we identified top priorities and gaps and needs in cancer and other NCD research in Vietnam. We organized two site visits for Vietnam National Cancer Institute delegates to observe epidemiologic research field operations, core laboratories, and biorepositories at Vanderbilt University Medical Center and Vanderbilt Epidemiology Center, as well as at several partner institutes in Shanghai, People’s Republic of China. We organized an in-country workshop on the principles and methodology of epidemiology and biostatistics. We sponsored overseas training for 4 Vietnamese scholars. We conducted two demonstration projects: a case-control study involving 501 patients with breast cancer and 468 controls, and a community survey for diabetes and other metabolic conditions involving 1,035 urban and rural residents of Vietnam. We also jointly sponsored with Vietnam National Cancer Institute an international conference on cancer research and prevention in 2017, and jointly published 11 papers.

CONCLUSION

Within a 3-year period, we have built a productive collaborative network and laid a solid foundation for building the V-CORE in Vietnam. We strive to maintain and expand the collaboration and bring the success of the National Cancer Institute grant work to full fruition.

BRCA2 Hypomorphic Missense Variants Confer Moderate Risks of Breast Cancer

Breast cancer risks conferred by many germline missense variants in the BRCA1 and BRCA2 genes, often referred to as variants of uncertain significance (VUS), have not been established. In this study, associations between 19 BRCA1 and 33 BRCA2 missense substitution variants and breast cancer risk were investigated through a breast cancer case-control study using genotyping data from 38 studies of predominantly European ancestry (41,890 cases and 41,607 controls) and nine studies of Asian ancestry (6,269 cases and 6,624 controls). The BRCA2 c.9104A>C, p.Tyr3035Ser (OR = 2.52; P = 0.04), and BRCA1 c.5096G>A, p.Arg1699Gln (OR = 4.29; P = 0.009) variant were associated with moderately increased risks of breast cancer among Europeans, whereas BRCA2 c.7522G>A, p.Gly2508Ser (OR = 2.68; P = 0.004), and c.8187G>T, p.Lys2729Asn (OR = 1.4; P = 0.004) were associated with moderate and low risks of breast cancer among Asians. Functional characterization of the BRCA2 variants using four quantitative assays showed reduced BRCA2 activity for p.Tyr3035Ser compared with wild-type. Overall, our results show how BRCA2 missense variants that influence protein function can confer clinically relevant, moderately increased risks of breast cancer, with potential implications for risk management guidelines in women with these specific variants. Cancer Res; 77(11); 2789-99. ©2017 AACR.

Fine-Mapping of the 1p11.2 Breast Cancer Susceptibility Locus

The Cancer Genetic Markers of Susceptibility genome-wide association study (GWAS) originally identified a single nucleotide polymorphism (SNP) rs11249433 at 1p11.2 associated with breast cancer risk. To fine-map this locus, we genotyped 92 SNPs in a 900kb region (120,505,799-121,481,132) flanking rs11249433 in 45,276 breast cancer cases and 48,998 controls of European, Asian and African ancestry from 50 studies in the Breast Cancer Association Consortium. Genotyping was done using iCOGS, a custom-built array. Due to the complicated nature of the region on chr1p11.2: 120,300,000-120,505,798, that lies near the centromere and contains seven duplicated genomic segments, we restricted analyses to 429 SNPs excluding the duplicated regions (42 genotyped and 387 imputed). Per-allelic associations with breast cancer risk were estimated using logistic regression models adjusting for study and ancestry-specific principal components. The strongest association observed was with the original identified index SNP rs11249433 (minor allele frequency (MAF) 0.402; per-allele odds ratio (OR) = 1.10, 95% confidence interval (CI) 1.08-1.13, P = 1.49 x 10-21). The association for rs11249433 was limited to ER-positive breast cancers (test for heterogeneity P≤8.41 x 10-5). Additional analyses by other tumor characteristics showed stronger associations with moderately/well differentiated tumors and tumors of lobular histology. Although no significant eQTL associations were observed, in silico analyses showed that rs11249433 was located in a region that is likely a weak enhancer/promoter. Fine-mapping analysis of the 1p11.2 breast cancer susceptibility locus confirms this region to be limited to risk to cancers that are ER-positive.

Association of genetic susceptibility variants for type 2 diabetes with breast cancer risk in women of European ancestry

PURPOSE

Type 2 diabetes (T2D) has been reported to be associated with an elevated risk of breast cancer. It is unclear, however, whether this association is due to shared genetic factors.

METHODS

We constructed a genetic risk score (GRS) using risk variants from 33 known independent T2D susceptibility loci and evaluated its relation to breast cancer risk using the data from two consortia, including 62,328 breast cancer patients and 83,817 controls of European ancestry. Unconditional logistic regression models were used to derive adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) to measure the association of breast cancer risk with T2D GRS or T2D-associated genetic risk variants. Meta-analyses were conducted to obtain summary ORs across all studies.

RESULTS

The T2D GRS was not found to be associated with breast cancer risk, overall, by menopausal status, or for estrogen receptor positive or negative breast cancer. Three T2D associated risk variants were individually associated with breast cancer risk after adjustment for multiple comparisons using the Bonferroni method (at p < 0.001), rs9939609 (FTO) (OR 0.94, 95 % CI = 0.92-0.95, p = 4.13E-13), rs7903146 (TCF7L2) (OR 1.04, 95 % CI = 1.02-1.06, p = 1.26E-05), and rs8042680 (PRC1) (OR 0.97, 95 % CI = 0.95-0.99, p = 8.05E-04).

CONCLUSIONS

We have shown that several genetic risk variants were associated with the risk of both T2D and breast cancer. However, overall genetic susceptibility to T2D may not be related to breast cancer risk.

No clinical utility of KRAS variant rs61764370 for ovarian or breast cancer

OBJECTIVE

Clinical genetic testing is commercially available for rs61764370, an inherited variant residing in a KRAS 3' UTR microRNA binding site, based on suggested associations with increased ovarian and breast cancer risk as well as with survival time. However, prior studies, emphasizing particular subgroups, were relatively small. Therefore, we comprehensively evaluated ovarian and breast cancer risks as well as clinical outcome associated with rs61764370.

METHODS

Centralized genotyping and analysis were performed for 140,012 women enrolled in the Ovarian Cancer Association Consortium (15,357 ovarian cancer patients; 30,816 controls), the Breast Cancer Association Consortium (33,530 breast cancer patients; 37,640 controls), and the Consortium of Modifiers of BRCA1 and BRCA2 (14,765 BRCA1 and 7904 BRCA2 mutation carriers).

RESULTS

We found no association with risk of ovarian cancer (OR=0.99, 95% CI 0.94-1.04, p=0.74) or breast cancer (OR=0.98, 95% CI 0.94-1.01, p=0.19) and results were consistent among mutation carriers (BRCA1, ovarian cancer HR=1.09, 95% CI 0.97-1.23, p=0.14, breast cancer HR=1.04, 95% CI 0.97-1.12, p=0.27; BRCA2, ovarian cancer HR=0.89, 95% CI 0.71-1.13, p=0.34, breast cancer HR=1.06, 95% CI 0.94-1.19, p=0.35). Null results were also obtained for associations with overall survival following ovarian cancer (HR=0.94, 95% CI 0.83-1.07, p=0.38), breast cancer (HR=0.96, 95% CI 0.87-1.06, p=0.38), and all other previously-reported associations.

CONCLUSIONS

rs61764370 is not associated with risk of ovarian or breast cancer nor with clinical outcome for patients with these cancers. Therefore, genotyping this variant has no clinical utility related to the prediction or management of these cancers.

Fine-mapping identifies two additional breast cancer susceptibility loci at 9q31.2

We recently identified a novel susceptibility variant, rs865686, for estrogen-receptor positive breast cancer at 9q31.2. Here, we report a fine-mapping analysis of the 9q31.2 susceptibility locus using 43 160 cases and 42 600 controls of European ancestry ascertained from 52 studies and a further 5795 cases and 6624 controls of Asian ancestry from nine studies. Single nucleotide polymorphism (SNP) rs676256 was most strongly associated with risk in Europeans (odds ratios [OR] = 0.90 [0.88-0.92]; P-value = 1.58 × 10(-25)). This SNP is one of a cluster of highly correlated variants, including rs865686, that spans ∼14.5 kb. We identified two additional independent association signals demarcated by SNPs rs10816625 (OR = 1.12 [1.08-1.17]; P-value = 7.89 × 10(-09)) and rs13294895 (OR = 1.09 [1.06-1.12]; P-value = 2.97 × 10(-11)). SNP rs10816625, but not rs13294895, was also associated with risk of breast cancer in Asian individuals (OR = 1.12 [1.06-1.18]; P-value = 2.77 × 10(-05)). Functional genomic annotation using data derived from breast cancer cell-line models indicates that these SNPs localise to putative enhancer elements that bind known drivers of hormone-dependent breast cancer, including ER-α, FOXA1 and GATA-3. In vitro analyses indicate that rs10816625 and rs13294895 have allele-specific effects on enhancer activity and suggest chromatin interactions with the KLF4 gene locus. These results demonstrate the power of dense genotyping in large studies to identify independent susceptibility variants. Analysis of associations using subjects with different ancestry, combined with bioinformatic and genomic characterisation, can provide strong evidence for the likely causative alleles and their functional basis.

Genome-wide association analysis of more than 120,000 individuals identifies 15 new susceptibility loci for breast cancer

Genome-wide association studies (GWAS) and large-scale replication studies have identified common variants in 79 loci associated with breast cancer, explaining ∼14% of the familial risk of the disease. To identify new susceptibility loci, we performed a meta-analysis of 11 GWAS, comprising 15,748 breast cancer cases and 18,084 controls together with 46,785 cases and 42,892 controls from 41 studies genotyped on a 211,155-marker custom array (iCOGS). Analyses were restricted to women of European ancestry. We generated genotypes for more than 11 million SNPs by imputation using the 1000 Genomes Project reference panel, and we identified 15 new loci associated with breast cancer at P < 5 × 10(-8). Combining association analysis with ChIP-seq chromatin binding data in mammary cell lines and ChIA-PET chromatin interaction data from ENCODE, we identified likely target genes in two regions: SETBP1 at 18q12.3 and RNF115 and PDZK1 at 1q21.1. One association appears to be driven by an amino acid substitution encoded in EXO1.

Risk factors for abandonment of Wilms tumor therapy in Kenya

BACKGROUND

Survival from Wilms tumor (WT) in sub-Saharan Africa remains dismal as a result of on-therapy mortality and treatment abandonment. Review of patients diagnosed from 2008 to 2011 in our Kenyan Wilms Tumor Registry showed a loss to follow up (LTFU) rate approaching 50%. The purpose of this study was to trace those LTFU, estimate the survival rate, and identify risk factors for treatment abandonment.

PROCEDURE

We administered a comprehensive survey to parents of patients with WT at the two largest referral hospitals in Kenya to identify barriers to care. We also telephoned families who had abandoned care to determine vital status and identify risk factors for treatment abandonment.

RESULTS

Of 136 registered patients, 77 were confirmed dead (56.7%), 38 remained alive (27.9%), and the vital status of 21 patients remains unknown (15.4%). After contacting 33 of the patients who either abandoned curative treatment (n = 34) or did not attend off-therapy visits (n = 20), the best estimate of 2-year overall survival of patients with WT in Kenya approaches 36%. Sixty-three percent of parents misunderstood treatment plans and 55% encountered financial barriers. When asked how to increase comfort with the child's treatment, 27% of parents volunteered improving inefficient services and 26% volunteered reducing drug-unavailability.

CONCLUSIONS

Treatment abandonment remains a significant problem contributing to increased mortality from WT in developing countries. This multi-center survey identified the barriers to treatment completion from the parental perspective to be lack of education about WT and treatment, financial constraints, need for quality improvement, and drug-unavailability. Pediatr Blood Cancer 2015;62:252-256. © 2014 Wiley Periodicals, Inc.

Fine-scale mapping of the 5q11.2 breast cancer locus reveals at least three independent risk variants regulating MAP3K1

Genome-wide association studies (GWASs) have revealed SNP rs889312 on 5q11.2 to be associated with breast cancer risk in women of European ancestry. In an attempt to identify the biologically relevant variants, we analyzed 909 genetic variants across 5q11.2 in 103,991 breast cancer individuals and control individuals from 52 studies in the Breast Cancer Association Consortium. Multiple logistic regression analyses identified three independent risk signals: the strongest associations were with 15 correlated variants (iCHAV1), where the minor allele of the best candidate, rs62355902, associated with significantly increased risks of both estrogen-receptor-positive (ER(+): odds ratio [OR] = 1.24, 95% confidence interval [CI] = 1.21-1.27, ptrend = 5.7 × 10(-44)) and estrogen-receptor-negative (ER(-): OR = 1.10, 95% CI = 1.05-1.15, ptrend = 3.0 × 10(-4)) tumors. After adjustment for rs62355902, we found evidence of association of a further 173 variants (iCHAV2) containing three subsets with a range of effects (the strongest was rs113317823 [pcond = 1.61 × 10(-5)]) and five variants composing iCHAV3 (lead rs11949391; ER(+): OR = 0.90, 95% CI = 0.87-0.93, pcond = 1.4 × 10(-4)). Twenty-six percent of the prioritized candidate variants coincided with four putative regulatory elements that interact with the MAP3K1 promoter through chromatin looping and affect MAP3K1 promoter activity. Functional analysis indicated that the cancer risk alleles of four candidates (rs74345699 and rs62355900 [iCHAV1], rs16886397 [iCHAV2a], and rs17432750 [iCHAV3]) increased MAP3K1 transcriptional activity. Chromatin immunoprecipitation analysis revealed diminished GATA3 binding to the minor (cancer-protective) allele of rs17432750, indicating a mechanism for its action. We propose that the cancer risk alleles act to increase MAP3K1 expression in vivo and might promote breast cancer cell survival.

Genetic variation in mitotic regulatory pathway genes is associated with breast tumor grade

Mitotic index is an important component of histologic grade and has an etiologic role in breast tumorigenesis. Several small candidate gene studies have reported associations between variation in mitotic genes and breast cancer risk. We measured associations between 2156 single nucleotide polymorphisms (SNPs) from 194 mitotic genes and breast cancer risk, overall and by histologic grade, in the Breast Cancer Association Consortium (BCAC) iCOGS study (n = 39 067 cases; n = 42 106 controls). SNPs in TACC2 [rs17550038: odds ratio (OR) = 1.24, 95% confidence interval (CI) 1.16-1.33, P = 4.2 × 10(-10)) and EIF3H (rs799890: OR = 1.07, 95% CI 1.04-1.11, P = 8.7 × 10(-6)) were significantly associated with risk of low-grade breast cancer. The TACC2 signal was retained (rs17550038: OR = 1.15, 95% CI 1.07-1.23, P = 7.9 × 10(-5)) after adjustment for breast cancer risk SNPs in the nearby FGFR2 gene, suggesting that TACC2 is a novel, independent genome-wide significant genetic risk locus for low-grade breast cancer. While no SNPs were individually associated with high-grade disease, a pathway-level gene set analysis showed that variation across the 194 mitotic genes was associated with high-grade breast cancer risk (P = 2.1 × 10(-3)). These observations will provide insight into the contribution of mitotic defects to histological grade and the etiology of breast cancer.

Genome-wide association study identifies 25 known breast cancer susceptibility loci as risk factors for triple-negative breast cancer

Triple-negative (TN) breast cancer is an aggressive subtype of breast cancer associated with a unique set of epidemiologic and genetic risk factors. We conducted a two-stage genome-wide association study of TN breast cancer (stage 1: 1529 TN cases, 3399 controls; stage 2: 2148 cases, 1309 controls) to identify loci that influence TN breast cancer risk. Variants in the 19p13.1 and PTHLH loci showed genome-wide significant associations (P < 5 × 10(-) (8)) in stage 1 and 2 combined. Results also suggested a substantial enrichment of significantly associated variants among the single nucleotide polymorphisms (SNPs) analyzed in stage 2. Variants from 25 of 74 known breast cancer susceptibility loci were also associated with risk of TN breast cancer (P < 0.05). Associations with TN breast cancer were confirmed for 10 loci (LGR6, MDM4, CASP8, 2q35, 2p24.1, TERT-rs10069690, ESR1, TOX3, 19p13.1, RALY), and we identified associations with TN breast cancer for 15 additional breast cancer loci (P < 0.05: PEX14, 2q24.1, 2q31.1, ADAM29, EBF1, TCF7L2, 11q13.1, 11q24.3, 12p13.1, PTHLH, NTN4, 12q24, BRCA2, RAD51L1-rs2588809, MKL1). Further, two SNPs independent of previously reported signals in ESR1 [rs12525163 odds ratio (OR) = 1.15, P = 4.9 × 10(-) (4)] and 19p13.1 (rs1864112 OR = 0.84, P = 1.8 × 10(-) (9)) were associated with TN breast cancer. A polygenic risk score (PRS) for TN breast cancer based on known breast cancer risk variants showed a 4-fold difference in risk between the highest and lowest PRS quintiles (OR = 4.03, 95% confidence interval 3.46-4.70, P = 4.8 × 10(-) (69)). This translates to an absolute risk for TN breast cancer ranging from 0.8% to 3.4%, suggesting that genetic variation may be used for TN breast cancer risk prediction.

Fine-scale mapping of the FGFR2 breast cancer risk locus: putative functional variants differentially bind FOXA1 and E2F1

The 10q26 locus in the second intron of FGFR2 is the locus most strongly associated with estrogen-receptor-positive breast cancer in genome-wide association studies. We conducted fine-scale mapping in case-control studies genotyped with a custom chip (iCOGS), comprising 41 studies (n = 89,050) of European ancestry, 9 Asian ancestry studies (n = 13,983), and 2 African ancestry studies (n = 2,028) from the Breast Cancer Association Consortium. We identified three statistically independent risk signals within the locus. Within risk signals 1 and 3, genetic analysis identified five and two variants, respectively, highly correlated with the most strongly associated SNPs. By using a combination of genetic fine mapping, data on DNase hypersensitivity, and electrophoretic mobility shift assays to study protein-DNA binding, we identified rs35054928, rs2981578, and rs45631563 as putative functional SNPs. Chromatin immunoprecipitation showed that FOXA1 preferentially bound to the risk-associated allele (C) of rs2981578 and was able to recruit ERα to this site in an allele-specific manner, whereas E2F1 preferentially bound the risk variant of rs35054928. The risk alleles were preferentially found in open chromatin and bound by Ser5 phosphorylated RNA polymerase II, suggesting that the risk alleles are associated with changes in transcription. Chromatin conformation capture demonstrated that the risk region was able to interact with the promoter of FGFR2, the likely target gene of this risk region. A role for FOXA1 in mediating breast cancer susceptibility at this locus is consistent with the finding that the FGFR2 risk locus primarily predisposes to estrogen-receptor-positive disease.

Functional variants at the 11q13 risk locus for breast cancer regulate cyclin D1 expression through long-range enhancers

Analysis of 4,405 variants in 89,050 European subjects from 41 case-control studies identified three independent association signals for estrogen-receptor-positive tumors at 11q13. The strongest signal maps to a transcriptional enhancer element in which the G allele of the best candidate causative variant rs554219 increases risk of breast cancer, reduces both binding of ELK4 transcription factor and luciferase activity in reporter assays, and may be associated with low cyclin D1 protein levels in tumors. Another candidate variant, rs78540526, lies in the same enhancer element. Risk association signal 2, rs75915166, creates a GATA3 binding site within a silencer element. Chromatin conformation studies demonstrate that these enhancer and silencer elements interact with each other and with their likely target gene, CCND1.

Multiple independent variants at the TERT locus are associated with telomere length and risks of breast and ovarian cancer

TERT-locus SNPs and leukocyte telomere measures are reportedly associated with risks of multiple cancers. Using the Illumina custom genotyping array iCOGs, we analyzed ∼480 SNPs at the TERT locus in breast (n = 103,991), ovarian (n = 39,774) and BRCA1 mutation carrier (n = 11,705) cancer cases and controls. Leukocyte telomere measurements were also available for 53,724 participants. Most associations cluster into three independent peaks. The minor allele at the peak 1 SNP rs2736108 associates with longer telomeres (P = 5.8 × 10(-7)), lower risks for estrogen receptor (ER)-negative (P = 1.0 × 10(-8)) and BRCA1 mutation carrier (P = 1.1 × 10(-5)) breast cancers and altered promoter assay signal. The minor allele at the peak 2 SNP rs7705526 associates with longer telomeres (P = 2.3 × 10(-14)), higher risk of low-malignant-potential ovarian cancer (P = 1.3 × 10(-15)) and greater promoter activity. The minor alleles at the peak 3 SNPs rs10069690 and rs2242652 increase ER-negative (P = 1.2 × 10(-12)) and BRCA1 mutation carrier (P = 1.6 × 10(-14)) breast and invasive ovarian (P = 1.3 × 10(-11)) cancer risks but not via altered telomere length. The cancer risk alleles of rs2242652 and rs10069690, respectively, increase silencing and generate a truncated TERT splice variant.

Large-scale genotyping identifies 41 new loci associated with breast cancer risk

Breast cancer is the most common cancer among women. Common variants at 27 loci have been identified as associated with susceptibility to breast cancer, and these account for ∼9% of the familial risk of the disease. We report here a meta-analysis of 9 genome-wide association studies, including 10,052 breast cancer cases and 12,575 controls of European ancestry, from which we selected 29,807 SNPs for further genotyping. These SNPs were genotyped in 45,290 cases and 41,880 controls of European ancestry from 41 studies in the Breast Cancer Association Consortium (BCAC). The SNPs were genotyped as part of a collaborative genotyping experiment involving four consortia (Collaborative Oncological Gene-environment Study, COGS) and used a custom Illumina iSelect genotyping array, iCOGS, comprising more than 200,000 SNPs. We identified SNPs at 41 new breast cancer susceptibility loci at genome-wide significance (P < 5 × 10(-8)). Further analyses suggest that more than 1,000 additional loci are involved in breast cancer susceptibility.

Genome-wide association studies identify four ER negative-specific breast cancer risk loci

Estrogen receptor (ER)-negative tumors represent 20-30% of all breast cancers, with a higher proportion occurring in younger women and women of African ancestry. The etiology and clinical behavior of ER-negative tumors are different from those of tumors expressing ER (ER positive), including differences in genetic predisposition. To identify susceptibility loci specific to ER-negative disease, we combined in a meta-analysis 3 genome-wide association studies of 4,193 ER-negative breast cancer cases and 35,194 controls with a series of 40 follow-up studies (6,514 cases and 41,455 controls), genotyped using a custom Illumina array, iCOGS, developed by the Collaborative Oncological Gene-environment Study (COGS). SNPs at four loci, 1q32.1 (MDM4, P = 2.1 × 10(-12) and LGR6, P = 1.4 × 10(-8)), 2p24.1 (P = 4.6 × 10(-8)) and 16q12.2 (FTO, P = 4.0 × 10(-8)), were associated with ER-negative but not ER-positive breast cancer (P > 0.05). These findings provide further evidence for distinct etiological pathways associated with invasive ER-positive and ER-negative breast cancers.

Identification of Genetic Susceptibility Loci for Colorectal Tumors in a Genome-Wide Meta-analysis

BACKGROUND & AIMS

Heritable factors contribute to the development of colorectal cancer. Identifying the genetic loci associated with colorectal tumor formation could elucidate the mechanisms of pathogenesis.

METHODS

We conducted a genome-wide association study that included 14 studies, 12,696 cases of colorectal tumors (11,870 cancer, 826 adenoma), and 15,113 controls of European descent. The 10 most statistically significant, previously unreported findings were followed up in 6 studies; these included 3056 colorectal tumor cases (2098 cancer, 958 adenoma) and 6658 controls of European and Asian descent.

RESULTS

Based on the combined analysis, we identified a locus that reached the conventional genome-wide significance level at less than 5.0 × 10(-8): an intergenic region on chromosome 2q32.3, close to nucleic acid binding protein 1 (most significant single nucleotide polymorphism: rs11903757; odds ratio [OR], 1.15 per risk allele; P = 3.7 × 10(-8)). We also found evidence for 3 additional loci with P values less than 5.0 × 10(-7): a locus within the laminin gamma 1 gene on chromosome 1q25.3 (rs10911251; OR, 1.10 per risk allele; P = 9.5 × 10(-8)), a locus within the cyclin D2 gene on chromosome 12p13.32 (rs3217810 per risk allele; OR, 0.84; P = 5.9 × 10(-8)), and a locus in the T-box 3 gene on chromosome 12q24.21 (rs59336; OR, 0.91 per risk allele; P = 3.7 × 10(-7)).

CONCLUSIONS

In a large genome-wide association study, we associated polymorphisms close to nucleic acid binding protein 1 (which encodes a DNA-binding protein involved in DNA repair) with colorectal tumor risk. We also provided evidence for an association between colorectal tumor risk and polymorphisms in laminin gamma 1 (this is the second gene in the laminin family to be associated with colorectal cancers), cyclin D2 (which encodes for cyclin D2), and T-box 3 (which encodes a T-box transcription factor and is a target of Wnt signaling to β-catenin). The roles of these genes and their products in cancer pathogenesis warrant further investigation.

Membrane progesterone receptor alpha as a potential prognostic biomarker for breast cancer survival: a retrospective study

Classically, the actions of progesterone (P4) are attributed to the binding of nuclear progesterone receptor (PR) and subsequent activation of its downstream target genes. These mechanisms, however, are not applicable to PR– or basal phenotype breast cancer (BPBC) due to lack of PR in these cancers. Recently, the function of membrane progesterone receptor alpha (mPRα) in human BPBC cell lines was studied in our lab. We proposed that the signaling cascades of P4→mPRα pathway may play an essential role in controlling cell proliferation and epithelial mesenchymal transition (EMT) of breast cancer. Using human breast cancer tissue microarrays, we found in this study that the average intensity of mPRα expression, but not percentage of breast cancer with high level of mPRα expression (mPRα-HiEx), was significantly lower in the TNM stage 4 patients compared to those with TNM 1–3 patients; and both average intensities of mPRα expression and mPRα-HiEx rates were significantly higher in cancers negative for ER, as compared with those cancers with ER+. However, after adjusting for age at diagnosis and/or TNM stage, only average intensities of mPRα expression were associated with ER status. In addition, we found that the rates of mPRα-HiEx were significantly higher in cancers with epithelial growth factor receptor–1 (EGFR+) and high level of Ki67 expression, indicating positive correlation between mPRα over expression and EGFR or Ki67. Further analysis indicated that both mPRα-HiEx rate and average intensity of mPRα expression were significantly higher in HER2+ subtype cancers (i.e. HER2+ER–PR–) as compared to ER+ subtype cancers. These data support our hypothesis that P4 modulates the activities of the PI3K and cell proliferation pathways through the caveolar membrane bound growth factor receptors such as mPRα and growth factor receptors. Future large longitudinal studies with larger sample size and survival outcomes are necessary to confirm our findings.

Population-based, case-control study of blood C-peptide level and breast cancer risk

Insulin resistance has been suggested to be associated with an increased risk of breast cancer. Insulin sensitivity can be measured using blood C-peptide, a marker of insulin secretion. It is thus conceivable that blood C-peptide levels may be associated with breast cancer risk. To evaluate this hypothesis, we analyzed data from a subset (143 case-control pairs matched by age and status of menopause) of women who participated in the Shanghai Breast Cancer Study, a population-based, case-control study conducted in Shanghai during 1996-1998. Fasting blood samples were collected from study subjects to measure C-peptide levels. For cancer patients, the samples were collected before any cancer therapy. Conditional logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals related to C-peptide levels. Breast cancer risk was increased with increasing levels of C-peptide (trend test, P = 0.01), with an odds ratio of 2.7 (95% confidence interval = 1.2-5.9) observed for the highest compared with the lowest tertile of C-peptide concentration after adjusting for body mass index and age at the first live birth. The risk was not altered after fully adjusting for other traditional risk factors for breast cancer. This positive association was observed in both pre and postmenopausal women and regardless of the levels of waist-to-hip ratio or body mass index. The results from this study were consistent with the insulin-resistance hypothesis for breast cancer and suggest that increased levels of C-peptide may contribute to the development of breast cancer.