Disparities In Breast Cancer Incidence Research Articles

Abstract P6-10-07: Differences in genome-wide DNA methylation levels in breast milk by race and lactation duration

Abstract Introduction: Identifying biomarkers of breast cancer risk among young women would have value in developing effective screening and prevention strategies at early ages. We have proposed that DNA methylation analysis of breast milk may provide breast cancer risk information among young women, and could possibly provide etiologic clues related to the higher rates of early onset cancers among African American as compared with White women in the US. Objective: The purpose of this project was to identify associations between genome-wide DNA methylation levels in breast milk and race adjusted for other breast cancer risk factors. Study Population: Cancer-free, lactating U.S. Black (n=57) and White (n=82) women, ages 19 to 44, provided frozen breast milk samples, as well as demographic, behavioral, and reproductive data, to the Breastmilk Laboratory at University of Massachusetts Amherst. Women were uniparous and did not have a personal history of breast cancer at the time of milk donation. Methods: DNA was extracted from breast milk samples using the phenol-chloroform method. Genome-wide methylation analysis was performed on breast milk samples using the Infinium HumanMethylation450 BeadChip. Probes with 50% or more missing data, cross-reactive probes, as well as probes with minor allelic frequency greater than 0.05 in European- or African-Americans were removed, leaving 379,042 CpG sites for analysis. Multivariate generalized linear regression models were used to examine associations between race and other breast cancer risk factors and methylation beta values, adjusting for potential confounding factors. P-values less than 1E-7 were considered statistically significant. Results: Black women in this study were more likely to be never smokers, to not have used over-the-counter pain medication in the past week, and to breastfeed longer. After adjustment by age, BMI, smoking status, and batch number, race was significantly associated with differential methylation at 1143 CpG sites, including 1024 at which Black women demonstrated increased methylation levels. Additionally, breastfeeding duration was associated with 269 CpG sites, with 268 showing a significant inverse relationship with methylation. Methylation sites significantly associated with Black race and lactation duration were located within tumor suppressor and promoter genes as well as in genes implicated in obesity and diabetes. Conclusion: This preliminarily analysis of DNA methylation in breast milk suggests that Black women have increased methylation and longer breastfeeding is associated with reduced methylation. Further research to understand how etiologic factors related to breast cancer may alter DNA methylation patterns in normal breast may lead to improved understanding of breast cancer risk at a young age and potentially causes of racial disparities in breast cancer incidence between White and Black women. Citation Format: Davis Lynn BC, Bodelon C, Pfeiffer RM, Yang HP, Yang H, Lee M, Laird PW, Campan M, Weisenberger DJ, Murphy J, Sherman ME, Browne EP, Anderton DL, Arcaro KF, Gierach GL. Differences in genome-wide DNA methylation levels in breast milk by race and lactation duration [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-10-07.

Racial/Ethnic Disparities in Breast Cancer Incidence, Risk Factors, Health Care Utilization, and Outcomes in the USA

Purpose of the Review This review examines racial/ethnic disparities in female breast cancer within the USA. Specifically, differences in breast cancer incidence, risk factors, health care utilization use, and outcomes among Caucasians and non-Caucasians are explored.

Differential Patterns of Risk Factors for Early-Onset Breast Cancer by ER Status in African American Women.

Given the disproportionately high incidence of early-onset breast cancer and aggressive subtypes, such as estrogen receptor (ER)-negative tumors, in African American (AA) women, elucidation of risk factors for early onset of specific subtypes of breast cancer is needed. We evaluated associations of reproductive, anthropometric, and other factors with incidence of invasive breast cancer by age at onset (<45, ≥45) in 57,708 AA women in the prospective Black Women's Health Study. From 1995 to 2013, we identified 529 invasive breast cancers among women <45 years of age (151 ER-, 219 ER+) and 1,534 among women ≥45 years (385 ER-, 804 ER+). We used multivariable Cox proportional hazards regression to estimate hazard ratios (HRs) for associations by age and ER status. Higher parity, older age at first birth, never having breastfed, and abdominal adiposity were associated with increased risk of early-onset ER- breast cancer: HRs were 1.71 for ≥3 births versus one birth; 2.29 for first birth after age 25 versus <20 years; 0.61 for ever having breastfed versus never; and 1.64 for highest versus lowest tertile of waist-to-hip ratio. These factors were not associated with ER- cancer in older women or with ER+ cancer regardless of age. Differences in risk factors by ER subtype were observed for breast cancer diagnosed before the age of 45 years. Etiological heterogeneity by tumor subtype in early-onset breast cancer, in combination with a higher prevalence of the risk factors in AA women, may explain, in part, racial disparities in breast cancer incidence. Cancer Epidemiol Biomarkers Prev; 26(2); 270-7. ©2016 AACR.

Incidence, mortality and receptor status of breast cancer in African Caribbean women: Data from the cancer registry of Guadeloupe

BackgroundGeographical disparities in breast cancer incidence and outcomes are reported worldwide. Women of African descent show lower incidence, higher mortality rates and earlier age of onset. We analyzed data from the cancer registry of Guadeloupe for the period 2008–2013. MethodsWe describe breast cancer characteristics by molecular subtype, as well as estimated observed and net survival. We used Cox proportional hazard models to determine associations between cancer subtypes and death rate, adjusted for variables of interest. ResultsOverall, 1275 cases were recorded with a mean age at diagnosis of 57(±14) years. World standardized incidence and mortality were respectively 71.9/100,000 and 14.1/100,000 person-years. Age-specific incidence rates were comparable to European and US populations below the age of 45, and higher in Guadeloupean women aged between 45 and 55 years. Overall, 65.1% of patients were hormone receptor (HR)+ and 20.1% were HR-. Triple negative breast cancers (TNBC) accounted for 14% of all cases, and were more frequent in patients under 40 (21.6% vs. 13.4%, p=0.02). Five-year net survival was 84.9% [81.4-88.6]. It was higher for HR+/Her2+ and HR+/Her2- subtypes, and lower for HR-/Her2+ and TNBC patients. ConclusionWe found high age-specific incidence rates of breast cancer in women aged 45 to 55 years, which warrants further investigation in our population. However, this population of mainly African descent had good overall survival rates, and data according to subtypes are consistent with those reported internationally. These results may suggest that poorer survival in other African descent populations may not be an inherent feature of the disease but may be amenable to improvement.

The experience of treatment barriers and their influence on quality of life in American Indian/Alaska Native breast cancer survivors.

American Indian and Alaska Native (AI/AN) breast cancer survivors experience disparities in breast cancer incidence and age-adjusted mortality compared with non-Hispanic white (NHW) breast cancer survivors. In addition, mortality-to-incidence rates indicate that AI/ANs continue to have the poorest survival from breast cancer compared with other racial groups. "Native American Cancer Education for Survivors" (NACES) is a cultural education and support intervention for AI/AN patients with cancer that collects data from voluntary participants through the NACES quality-of-life (QOL) survey regarding their cancer experience and survivor journey. Data from the NACES QOL survey were analyzed to determine whether barriers accessing and during initial cancer treatment impacted QOL domains for AI/AN cancer survivors. Exploratory analyses of selected variables were conducted and were followed by Kruskal-Wallis tests to determine whether these barriers influenced survivorship QOL for AI/AN breast cancer survivors. AI/AN breast cancer survivors' social QOL was significantly affected by barriers to accessing cancer treatment. Many respondents experienced barriers, including a lack of cancer care at local clinics and the distance traveled to receive cancer care. During treatment, too much paperwork and having to wait too long in the clinic for cancer care were the most frequently reported barriers. Treatment barriers influence AI/AN breast cancer survivors' social QOL. Mediating these barriers is crucial to ameliorating AI/AN survivors' disparities when accessing and completing cancer treatment and improving survivorship QOL. Cancer 2017;123:861-68. © 2016 American Cancer Society.

Patterns and Trends in Age-Specific Black-White Differences in Breast Cancer Incidence and Mortality - United States, 1999-2014.

Breast cancer continues to be the most commonly diagnosed cancer and the second leading cause of cancer deaths among U.S. women (1). Compared with white women, black women historically have had lower rates of breast cancer incidence and, beginning in the 1980s, higher death rates (1). This report examines age-specific black-white disparities in breast cancer incidence during 1999-2013 and mortality during 2000-2014 in the United States using data from United States Cancer Statistics (USCS) (2). Overall rates of breast cancer incidence were similar, but death rates remained higher for black women compared with white women. During 1999-2013, breast cancer incidence decreased among white women but increased slightly among black women resulting in a similar average incidence at the end of the period. Breast cancer incidence trends differed by race and age, particularly from 1999 to 2004-2005, when rates decreased only among white women aged ≥50 years. Breast cancer death rates decreased significantly during 2000-2014, regardless of age with patterns varying by race. For women aged ≥50 years, death rates declined significantly faster among white women compared with black women; among women aged <50 years, breast cancer death rates decreased at the same rate among black and white women. Although some of molecular factors that lead to more aggressive breast cancer are known, a fuller understanding of the exact mechanisms might lead to more tailored interventions that could decrease mortality disparities. When combined with population-based approaches to increase knowledge of family history of cancer, increase physical activity, promote a healthy diet to maintain a healthy bodyweight, and increase screening for breast cancer, targeted treatment interventions could reduce racial disparities in breast cancer.

Breast Cancer and African Ancestry: Lessons Learned at the 10-Year Anniversary of the Ghana-Michigan Research Partnership and International Breast Registry.

Women with African ancestry in western, sub-Saharan Africa and in the United States represent a population subset facing an increased risk of being diagnosed with biologically aggressive phenotypes of breast cancer that are negative for the estrogen receptor, the progesterone receptor, and the HER2/neu marker. These tumors are commonly referred to as triple-negative breast cancer. Disparities in breast cancer incidence and outcome related to racial or ethnic identity motivated the establishment of the International Breast Registry, on the basis of partnerships between the Komfo Anokye Teaching Hospital in Kumasi, Ghana, the University of Michigan Comprehensive Cancer Center in Ann Arbor, Michigan, and the Henry Ford Health System in Detroit, Michigan. This research collaborative has featured educational training programs as well as scientific investigations related to the comparative biology of breast cancer in Ghanaian African, African American, and white/European American patients. Currently, the International Breast Registry has expanded to include African American patients throughout the United States by partnering with the Sisters Network (a national African American breast cancer survivors’ organization) and additional sites in Ghana (representing West Africa) as well as Ethiopia (representing East Africa). Its activities are now coordinated through the Henry Ford Health System International Center for the Study of Breast Cancer Subtypes. Herein, we review the history and results of this international program at its 10-year anniversary.

Abstract 1779: Risk factors for early-onset ER- and ER+ breast cancer in African American women

Abstract Introduction: Relative to white women, African American (AA) women have a disproportionately high incidence of early-onset breast cancer, particularly higher incidence of aggressive breast cancer subtypes such as estrogen receptor (ER) negative tumors. Elucidation of risk factors for early-onset of specific subtypes of breast cancer is needed. Methods: We evaluated associations of reproductive and lifestyle factors with early-onset invasive breast cancer, defined as diagnosis before age 50, in 47,212 AA women ages 21-49 in the Black Women's Health Study (BWHS). The BWHS is an ongoing prospective cohort study in the U.S. that began in 1995. Risk factor information is updated every two years via mailed questionnaires. Incident cases were self-reported on biennial questionnaires or identified through death records and confirmed by medical records and cancer registry data. Through 2013, we identified 192 ER- and 322 ER+ invasive breast cancers diagnosed before age 50. We used multivariable Cox proportional hazards regression, stratified by age, to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of family history of breast cancer, age at menarche, parity, age at first birth, years since last birth, lactation, body mass index (recent and at age 18), waist-to-hip ratio, oral contraceptive use, alcohol consumption, smoking history, and physical activity, with risk of ER- and ER+ early-onset breast cancer, separately. Results: The strongest associations were observed for family history of breast cancer, early age at menarche, and lower body mass index at age 18, and these factors were associated with increased incidence of both ER- and ER+ breast cancer. Oral contraceptive use within the past 10 years was also associated with increased risk of both subtypes. High waist-to-hip ratio (HR for top tertile vs. bottom: 1.46, 95% CI: 0.98, 2.19) and high parity (HR for 3+ births vs. 1: 1.43, 95% CI: 0.88, 2.32) were associated with increased risk of ER- breast cancer, while breastfeeding was associated with a reduced risk (HR for ever vs. never: 0.68, 95% CI: 0.47, 0.97). In contrast, higher parity was associated with a reduced risk of ER+ cancer (HR for 3+ births vs. 1: 0.68, 95% CI: 0.45, 1.01). Recent pregnancy (HR for &amp;lt;10 years vs. 10 or more years: 1.33, 95% CI: 0.94, 1.88) and greater alcohol consumption (HR for 7+ drinks/week vs. &amp;lt;1/week: 1.33, 95% CI: 0.81, 2.17) were associated with an increased risk of ER+ tumors. Conclusions: Differential associations of risk factors for ER- vs. ER+ breast cancers in young AA women suggest etiological heterogeneity by tumor subtypes. These differences could explain, in part, disparities in breast cancer incidence and mortality between black and white women. Some identified risk factors are potentially modifiable, suggesting possible opportunities for prevention. Citation Format: Kimberly A. Bertrand, Lynn Rosenberg, Julie R. Palmer. Risk factors for early-onset ER- and ER+ breast cancer in African American women. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1779.

Disparities in Breast Cancer Incidence, Mortality, and Quality of Care among African American and European American Women in South Carolina.

Breast cancer is the most frequently diagnosed cancer among women and the second-leading cause of female cancer deaths in the United States. African Americans and other minorities in the United States experience lower survival rates and have a worse prognosis than European Americans despite European Americans having a much higher incidence of the disease. Adherence to breast cancer treatment-quality measures is limited, particularly when the data are stratified by race/ethnicity. We aimed to examine breast cancer incidence and mortality trends in South Carolina by race and explore possible racial disparities in the quality of breast cancer treatment received in South Carolina. African Americans have high rates of mammography and clinical breast examination screenings yet suffer lower survival compared with European Americans. For most treatment-quality metrics, South Carolina fairs well in comparison to the United States as a whole; however, South Carolina hospitals overall lag behind South Carolina Commission on Cancer-accredited hospitals for all measured quality indicators, including needle biopsy utilization, breast-conserving surgeries, and timely use of radiation therapy. Accreditation may a play a major role in increasing the standard of care related to breast cancer diagnosis and treatment. These descriptive findings may provide significant insight for future interventions and policies aimed at eliminating racial/ethnic disparities in health outcomes. Further risk-reduction approaches are necessary to reduce minority group mortality rates, especially among African American women.

Socioeconomic disparities in breast cancer incidence and survival among parous women: findings from a population-based cohort, 1964-2008.

BackgroundSocioeconomic position (SEP) has been associated with breast cancer incidence and survival. We examined the associations between two socioeconomic indicators and long-term breast cancer incidence and survival in a population-based cohort of parous women.MethodsResidents of Jerusalem who gave birth between 1964–1976 (n = 40,586) were linked to the Israel Cancer Registry and Israel Population Registry to determine breast cancer incidence and vital status through mid-2008. SEP was assessed by husband’s occupation and the woman’s education. We used log ranks tests to compare incidence and survival curves by SEP, and Cox proportional hazard models to adjust for demographic, reproductive and diagnostic factors and assess effect modification by ethnic origin.ResultsIn multivariable models, women of high SEP had a greater risk of breast cancer compared to women of low SEP (Occupation: HR 1.18, 95 % CI 1.03-1.35; Education: HR 1.39, 95 % CI 1.21-1.60) and women of low SEP had a greater risk of mortality after a breast cancer diagnosis (Occupation: HR 1.33, 95 % CI 1.04-1.70; Education: HR 1.37, 95 % CI 1.06-1.76). The association between education and survival was modified by ethnic origin, with a gradient effect observed only among women of European origin. Women of Asian, North African and Israeli origin showed no such trend.ConclusionsSEP was associated with long-term breast cancer incidence and survival among Israeli Jews. Education had a stronger effect on breast cancer outcomes than occupation, suggesting that a behavioral mechanism may underlie disparities. More research is needed to explain the difference in the effect of education on survival among European women compared to women of other ethnicities.

Abstract B43: Disparities in mortality and five-year survival by race and socioeconomic status in white and African American women diagnosed with breast cancer in metropolitan Detroit

Abstract Background: Racial and, to a lesser extent, socioeconomic disparities in breast cancer incidence and mortality have been well documented; however, little is known about whether observed racial disparities differ by socioeconomic status. Methods: We used data from the population-based Metropolitan Detroit Cancer Surveillance System to estimate hazard ratios of death for non-Hispanic white (N = 31,102, including 8,174 deaths) and African-American women (N = 9,257, including 3,133 deaths) ages 18 and older diagnosed with incident, invasive breast cancer with recorded stage between 2000 and 2013 in Oakland, Wayne, and Macomb counties in Michigan and to estimate 5-year survival percentages for women diagnosed between 2000 and 2008 (N = 18,922). Neighborhood poverty was measured using the proportion of households with incomes below the federal poverty level in 2000 in the women's census tracts of residence at diagnosis. We used Cox proportional hazards models controlling for age at diagnosis, year of diagnosis, and cancer stage at diagnosis to estimate hazard ratios (HR) and 95% confidence intervals (CI) associated with mortality. Standard errors were adjusted to account for unobserved correlation between residents of the same census tracts. Results: Risk of death in African-American women diagnosed with breast cancer was 57% higher than for white women (HR: 1.57, 95% CI: 1.48, 1.67), and this association attenuated when also controlling for neighborhood poverty (HR: 1.31, 95% CI: 1.20, 1.42). Living in high-poverty neighborhoods was associated with a 77% higher risk of death (HR: 1.77, 95% CI: 1.64, 1.91), and this association also attenuated when controlling for race (HR: 1.46, 95% CI: 1.33, 1.62). Risk of death was higher for African-American women than for white women at every level of neighborhood poverty, although the associations were stronger in the lowest poverty areas (HR associated with being African-American: 1.68, 95% CI: 1.33, 2.12) than in the highest-poverty areas (HR: 1.23, 95% CI 1.08, 1.40). Among white women, higher neighborhood poverty was associated with higher risk of death (HR for high- vs. low-poverty areas: 1.57, 95% CI: 1.37, 1.79), but living in higher-poverty areas was not associated with mortality among African-American women with breast cancer (HR for high- vs. low-poverty areas: 1.21, 95% CI: 0.96, 1.51). Five-year survival was higher in white women (77.6%) than in African-American women (65.3%) overall. This difference in 5-year survival was largest for women living in the lowest-poverty areas (81.5% for whites vs. 70.1% for African-Americans), but was much smaller for women in the highest-poverty areas (66.2% for whites vs. 62.3% for African Americans). Conclusions: Although important disparities in mortality exist for African-American women compared with white women with breast cancer, disparities also exist by socioeconomic status, particularly for white women. The extent to which these disparities could be due to treatment differences, age at diagnosis, and type of breast cancer is being examined. It is important to consider socioeconomic status in addition to race when identifying and addressing disparities in breast cancer outcomes. Citation Format: Theresa A. Hastert, Ann G. Schwartz, Terrance L. Albrecht. Disparities in mortality and five-year survival by race and socioeconomic status in white and African American women diagnosed with breast cancer in metropolitan Detroit. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr B43.

The Incidence of Breast Cancer among Disabled Kansans with Medicare

BACKGROUND: Breast cancer disparities by disability status are poorly understood. While previous studies have shown increased odds of late stage at diagnosis, it is unclear whether the incidence of breast cancer varies by disability status. METHODS: To assess cancer incidence and stage at diagnosis among disabled and nondisabled Medicare beneficiaries in Kansas, a retrospective cohort study was conducted using linked Medicare enrollment and Kansas Cancer Registry data from 2007 to 2009. Disability status was determined by the indicator for the original reason for Medicare eligibility. RESULTS: Among the 651,337 Medicare beneficiaries included in the cohort, there were 2,384 cases of breast cancer. The age-adjusted incidence was 313 per 100,000 among female beneficiaries with disabilities and 369 per 100,000 among nondisabled female beneficiaries. The adjusted incidence rate ratio was 0.93 (95% CI 0.73-1.18). When assessing stage at diagnosis, there was no difference in the odds of late stage at diagnosis by disability status (OR = 1.02; 95% CI 0.68-1.50). CONCLUSION: No significant difference in incidence or stage at diagnosis was identified among this cohort. The use of Medicare eligibility to define disability status presented a number of limitations. Future studies should seek alternate definitions of disability to assess disparities in breast cancer incidence, including definitions using Medicare claims data.

Global surgical oncology disease burden: addressing disparities via global surgery initiatives: the University of Michigan International Breast Cancer Registry.

Disparities in breast cancer incidence and outcome between African American and white American women are multifactorial in etiology. The increased frequency of triple-negative breast cancers (TNBC) in African American patients suggests the possible contribution of hereditary factors related to African ancestry. The University of Michigan (UM)-Komfo Anoyke Teaching Hospital (KATH) Breast Cancer Research Collaborative and International Breast Registry was established in 2004. It features epidemiologic information, tumor tissue, and germline DNA specimens from African American, white American, and Ghanaian women. This research collaborative has generated valuable findings regarding the pathogenesis and patterns of TNBC while concomitantly improving the standard of breast oncology care in Ghana. This partnership has also yielded important opportunities for academic and educational exchange. It has expanded to involve other sites in Africa and Haiti. The UM-KATH collaborative is a model for demonstrating the research and academic exchange value of international partnerships.

Associations of Hormone-Related Factors With Breast Cancer Risk According to Hormone Receptor Status Among White and African American Women

BackgroundCauses of racial disparities in breast cancer incidence and mortality between white and African American women remain unclear. This study evaluated associations of menstrual and reproductive factors with breast cancer risk by race and cancer subtypes. Patients and MethodsIncluded in the study were 1866 breast cancer cases and 2306 controls recruited in the Nashville Breast Health Study, a population-based case-control study. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). ResultsAfrican American women were more likely to have estrogen receptor-negative (ER−), progesterone receptor-negative (PR−), and triple-negative (ER−PR−HER2−) breast cancer than white women. Age at menarche (≥ 14 years) and multiparity (≥ 3 live births) were inversely associated with ER+ tumors only, whereas late age at first live birth (> 30 years) and nulliparity were associated with elevated risk; such associations were predominantly seen in white women (OR = 0.70, 95% CI = 0.55-0.88; OR = 0.72, 95% CI = 0.56-0.92; OR = 1.42, 95% CI = 1.13-1.79; OR = 1.32, 95% CI = 1.06-1.63, respectively). Age at menopause between 47 and 51 years was associated with elevated risk of ER− tumors in both white and African American women. Among women who had natural menopause, positive association between ever-use of hormone replacement therapy and breast cancer risk was seen in white women only (OR = 1.39, 95% CI = 1.03-1.87). ConclusionThis study suggests that certain hormone-related factors are differentially associated with risk of breast cancer subtypes, and these associations also differ by race.

Links between obesity, diabetes and ethnic disparities in breast cancer among Hispanic populations

Breast cancer is the most prevalent malignancy in women worldwide and is a growing concern due to rising incidence and ongoing ethnic disparities in both incidence and mortality. A number of factors likely contribute to these trends including rising rates of obesity and diabetes across the globe and differences in genetic predisposition. Here, we emphasize Hispanic populations and summarize what is currently known about obesity, diabetes and individual genetic predisposition as they relate to ethnic disparities in breast cancer incidence and mortality. In addition, we discuss potential contributions to breast cancer aetiology from molecular mechanisms associated with obesity and diabetes including dyslipidemia, hyperglycaemia, hyperinsulinaemia, endocrine dysfunction and inflammation. We propose that unique differences in diet and lifestyle coupled with individual genetic predisposition and endocrine/immune dysfunction explain most of the ethnic disparities seen in breast cancer incidence and mortality.

Variation in tumor natural history contributes to racial disparities in breast cancer stage at diagnosis

Black women tend to be diagnosed with breast cancer at a more advanced stage than whites and subsequently experience elevated breast cancer mortality. We sought to determine whether there are racial differences in tumor natural history that contribute to these disparities. We used the University of Wisconsin Breast Cancer Simulation Model, a validated member of the National Cancer Institute's Cancer Intervention and Surveillance Modeling Network, to evaluate the contribution of racial differences in tumor natural history to observed disparities in breast cancer incidence. We fit eight natural history parameters in race-specific models by calibrating to the observed race- and stage-specific 1975-2000 U.S. incidence rates, while accounting for known racial variation in population structure, underlying risk of breast cancer, screening mammography utilization, and mortality from other causes. The best fit models indicated that a number of natural history parameters must vary between blacks and whites to reproduce the observed stage-specific incidence patterns. The mean of the tumor growth rate parameter was 63.6% higher for blacks than whites (0.18, SE 0.04 vs. 0.11, SE 0.02). The fraction of tumors considered highly aggressive based on their tendency to metastasize at a small size was 2.2 times greater among blacks than whites (0.41, SE 0.009 vs. 0.019, SE 0.008). Based on our simulation model, breast tumors in blacks grow faster and are more likely to metastasize earlier than tumors in whites. These differences suggest that targeted prevention and detection strategies that go beyond equalizing access to mammography may be needed to eliminate breast cancer disparities.

Racial/Ethnic Disparities in Breast Cancer Risk: Genomics Meets Metabolomics

Although breast cancer is by far the most common cancer among all women worldwide, its incidence rates vary substantially in different populations. In the United States, rates are highest among white women, followed by African American (AA) and Hispanic American (HA) women. Among HA women, breast cancer incidence rates are higher among those born in the United States than among first-generation immigrants, who, in turn, have higher rates than their counterparts in their countries of origin. Among foreign-born HA women, breast cancer risk has been shown to increase with the duration of U.S. residency, degree of acculturation, and younger age at migration, underscoring the importance of environmental influence on breast cancer risk. On the other hand, overall breast cancer risk among HA women has been shown to increase with the degree of European contribution to their genetic admixture. Among AA women, a higher proportion of European ancestry has been associated with a less aggressive form of breast cancer (estrogen receptor [ER] positive/progesterone receptor [PR] positive and localized). These observations highlight the need for understanding the population genetic substructure in the evaluation of racial/ ethnic disparities in breast cancer incidence and prognosis. Although breast cancer is more likely to occur in white women, AA and HA breast cancer patients are more likely to die of their disease. The age at onset tends to be earlier in AA and HA women, and these cases tend to have more aggressive histologic characteristics, including the triplenegative breast cancer (TNBC) that lacks expression of ER, PR, and human epidermal growth factor receptor 2 (HER2). Interestingly, limited evidence suggests that TNBC is also overrepresented among Hispanic and African women in their countries of origin. The predisposition to more aggressive tumors likely has contributed to the higher mortality rates among young minority women. However, the poor prognosis of breast cancer among AA and HA women has also been attributed, in part, to inadequate health insurance, limited access to mammography, advanced disease stage at diagnosis, delayed and inadequate treatment, and a high prevalence of comorbidity.

Invasive breast cancer incidence trends by detailed race/ethnicity and age.

Racial/ethnic disparities in breast cancer incidence may contain important evidence for understanding and control of the disease. Monitoring the incidence trends of breast cancer by race/ethnicity allows identification of high risk groups and development of targeted prevention programs. Using population-based cancer registry data from the Los Angeles Cancer Surveillance Program, we examined the invasive female breast cancer incidence trends among the diverse racial/ethnic populations in Los Angeles County, California, from 1972 to 2007. Age-adjusted incidence rates (AAIRs) and age-specific incidence rates (ASIRs) were calculated and examined respectively for non-Hispanic (NH) white, black, Hispanic, Chinese, Filipina, Japanese and Korean women by calendar year and time period. Rising trends of AAIRs were found in all racial/ethnic groups during the 1980s and 1990s. The breast cancer risk increased more substantially in Japanese and Filipinas than in Chinese and Koreans. During 2000-2007, the trends of AAIRs declined significantly among NH white women and slightly in blacks, remained unchanged for Hispanics and continued to rise significantly among all Asian subgroups. The patterns of ASIRs by race/ethnicity changed dramatically over time. By 2000-2007, younger Hispanic women had the lowest breast cancer risk, replacing the Chinese and Koreans who formerly had the lowest risk. Rapidly increasing breast cancer incidence trends among Asian-Americans underline the importance of behavioral and lifestyle changes as a result of acculturation on the development of the disease. The unique trends of breast cancer incidence by race/ethnicity suggest the need for targeted breast cancer control programs for different racial/ethnic populations.

Breast cancer treatment and ethnicity in British Columbia, Canada

BackgroundRacial and ethnic disparities in breast cancer incidence, stage at diagnosis, survival and mortality are well documented; but few studies have reported on disparities in breast cancer treatment. This paper compares the treatment received by breast cancer patients in British Columbia (BC) for three ethnic groups and three time periods. Values for breast cancer treatments received in the BC general population are provided for reference.MethodsInformation on patients, tumour characteristics and treatment was obtained from BC Cancer Registry (BCCR) and BC Cancer Agency (BCCA) records. Treatment among ethnic groups was analyzed by stage at diagnosis and time period at diagnosis. Differences among the three ethnic groups were tested using chi-square tests, Fisher exact tests and a multivariate logistic model.ResultsThere was no significant difference in overall surgery use for stage I and II disease between the ethnic groups, however there were significant differences when surgery with and without radiation were considered separately. These differences did not change significantly with time. Treatment with chemotherapy and hormone therapy did not differ among the minority groups.ConclusionThe description of treatment differences is the first step to guiding interventions that reduce ethnic disparities. Specific studies need to examine reasons for the observed differences and the influence of culture and beliefs.

Temporal trends in area socioeconomic disparities in breast-cancer incidence and mortality, 1988–2005

Since an overarching goal of Healthy People 2010 was to eliminate health disparities, we determined temporal trends in socioeconomic disparities in five breast-cancer indicators (in situ, stage I, lymph-node positive, and locally advanced breast-cancer incidence, and breast-cancer mortality) by county socioeconomic deprivation using 1988-2005 population-based breast-cancer data. Using 1988-2005 data from women aged 40 and older from 200 counties in the Surveillance, Epidemiology, and End Results program, we examined trends in temporal disparities in the five breast-cancer indicators across quartiles of county socioeconomic deprivation. County-level trends were summarized using the estimated annual percentage change. Observed county rates were smoothed using Bayesian hierarchical spatiotemporal methods to calculate measures of absolute and relative disparity (using absolute and relative concentration indices) and their changes over time. Large increases in in situ breast cancer rates since 1988 were observed for each of the deprivation quartiles. Absolute and relative disparity both increased over time, suggesting increasing disparities across levels of county deprivation. Absolute and relative concentration indices were near zero for the other four breast-cancer indicators, suggesting no disparities among the four quartiles of county deprivation during 1988-2005. Efforts to target counties aimed at increasing breast-cancer screening based on their level of deprivation will not likely be beneficial.