Age-Related Crossover in Breast Cancer Incidence Rates Between Black and White Ethnic Groups

Biostatistics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, United States Department of Health and Human Services, Bethesda, MD 20892-7244, USA.
Journal of the National Cancer Institute (Impact Factor: 12.58). 01/2009; 100(24):1804-14. DOI: 10.1093/jnci/djn411
Source: PubMed


Although breast cancer incidence is higher in black women than in white women among women younger than 40 years, the reverse is true among those aged 40 years or older. This crossover in incidence rates between black and white ethnic groups has been well described, has not been completely understood, and has been viewed as an artifact.
To quantify this incidence rate crossover, we examined data for 440 653 women with invasive breast cancer from the National Cancer Institute's Surveillance, Epidemiology, and End Results database from January 1, 1975, through December 31, 2004. Data on invasive female breast cancers were stratified by race, age at diagnosis, year of diagnosis, and tumor characteristics. Standard descriptive analyses were supplemented with Poisson regression models, age-period-cohort models, and two-component mixture models. All statistical tests were two-sided.
We observed qualitative (ie, crossing or reversing) interactions between age and race. That is, age-specific incidence rates overall (expressed as number of breast cancers per 100 000 woman-years) were higher among black women (15.5) than among white women (13.1) younger than 40 years (difference = 2.4, 95% confidence interval [CI] = 2.4 to 2.4), and then, age-specific rates crossed with rates higher among white women (281.3) than among black women (239.5) aged 40 years or older (difference = 41.8, 95% CI = 41.7 to 41.9). The black-to-white incidence rate crossover was observed for all tumor characteristics assessed, although the crossover occurred at earlier ages of diagnosis for low-risk tumor characteristics than for high-risk tumor characteristics. The incidence rate crossover between ethnic groups was robust (ie, reliable and reproducible) to adjustment for calendar period and birth cohort effects in age-period-cohort models (P < .001 for difference by race).
Although this ecologic study cannot determine the individual-level factors responsible for the racial crossover in vital rates, it confirms that the age-related crossover in breast cancer incidence rates between black and white ethnic groups is a robust age-specific effect that is independent of period and cohort effects.

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Available from: Idan Menashe, Oct 13, 2015
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    • "Breast cancer is the most common cancer among women in the United States, accounting for 29% of all newly diagnosed cancers [1]. Although breast cancer incidence at older ages is lower among African American (AA) women than European American (EA) women, the incidence rate is higher in AA women at younger ages (50 years) [2]. More importantly, AA women are more likely to be diagnosed with aggressive tumors that are high grade and negative for estrogen receptors (ER), which are often associated with poorer disease prognosis [3]. "
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    ABSTRACT: African American (AA) women are more likely than European American (EA) women to be diagnosed with early, aggressive breast cancer. Possible differences in innate immune pathways (e.g., inflammatory responses) have received little attention as potential mechanisms underlying this disparity. We evaluated distributions of selected genetic variants in innate immune pathways in AA and EA women, and examined their associations with breast cancer risk within the Women's Circle of Health Study (WCHS). In stage I of the study (864 AA and 650 EA women) we found that genotype frequencies for 35 of 42 tested SNPs (18 candidate genes) differed between AAs and EAs (corroborated by ancestry informative markers). Among premenopausal AA women, comparing variant allele carriers to non-carriers, reduced breast cancer risk was associated with CXCL5-rs425535 (OR=0.61, P=0.02), while among EA women, there were associations with TNFA-rs1799724 (OR =2.31, P =0.002) and CRP-rs1205 (OR=0.54, P=0.01). For postmenopausal women, IL1B-rs1143627 (OR=1.80, P=0.02) and IL1B-rs16944 (OR=1.85, P =0.02) were associated with risk among EA women, with significant associations for TNFA-rs1799724 limited to estrogen receptor (ER) positive cancers (OR=2.0, P =0.001). However, none of the SNPs retained significance after Bonferroni adjustment for multiple testing at the level of P0.0012 (0.05/42) except for TNFA-rs1799724 in ER positive cancers. In a stage II validation (1,365 AA and 1,307 EA women), we extended evaluations for four SNPs (CCL2-rs4586, CRP-rs1205, CXCL5-rs425535, and IL1RN-rs4251961), which yielded similar results. In summary, distributions of variants in genes involved in innate immune pathways were found to differ between AA and EA populations, and showed differential associations with breast cancer according to menopausal or ER status. These results suggest that immune adaptations suited to ancestral environments may differentially influence breast cancer risk among EA and AA women.
    PLoS ONE 08/2013; 8(8):e72619. DOI:10.1371/journal.pone.0072619 · 3.23 Impact Factor
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    • "One study showed the mean age of diagnosis in black patient was 57.6 years with large tumor size compared to 62.6 years in white patients. The overall incidence was lower in black women although for patients younger than 40 years the incidence was higher by 20% in black women[2]. The estimated age standardized rates for breast cancer incidence in sub-Saharan Africa range from 15 to 53 per 100, 000 women, which is lower than what is seen in Western countries[3]. "
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    ABSTRACT: Breast cancer is more common in Western Countries compared to African populations. However in African population, it appears that the disease tends to be more aggressive and occurring at a relatively young age at the time of presentation. The aim of this study was to describe the trend of Breast Cancer in Northwestern Tanzania. This was a retrospective study which involved all cases of breast cancer diagnosed histologically at Bugando Medical Center from 2002 to 2010. Histological results and slides were retrieved from the records in the Pathology department, clinical information and demographic data for patients were retrieved from surgical wards and department of medical records. Histology slides were re-evaluated for the histological type, grade (By modified Bloom-Richardson score), and presence of necrosis and skin involvement. Data was entered and analyzed by SPSS computer software version 15. There were 328 patients histologically confirmed to have breast cancer, the mean age at diagnosis was 48.7 years (+/- 13.1). About half of the patients (52.4%) were below 46 years of age, and this group of patients had significantly higher tendency for lymph node metastasis (p = 0.012). The tumor size ranged from 1 cm to 18 cm in diameter with average (mean) of 5.5 cm (+/- 2.5), and median size of 6 cm. Size of the tumor (above 6 cm in diameter) and presence of necrosis within the tumor was significantly associated with high rate of lymph node metastasis (p = 0.000). Of all patients, 64% were at clinical stage III (specifically IIIB) and 70.4% had lymph node metastasis at the time of diagnosis. Only 4.3% of the patients were in clinical stage I at the time of diagnosis. Majority of the patients had invasive ductal carcinoma (91.5%) followed by mucinous carcinoma (5.2%), Invasive lobular carcinoma (3%) and in situ ductal carcinoma (0.3%). In all patients, 185 (56.4%) had tumor with histological grade 3. Breast cancer in this region show a trend towards relative young age at diagnosis with advanced stage at diagnosis and high rate of lymph node metastasis. Poor Referral system, lack of screening programs and natural aggressive biological behavior of tumor may contribute to advanced disease at the time of diagnosis.
    BMC Research Notes 06/2011; 4(1):214. DOI:10.1186/1756-0500-4-214
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    • "Differences in breast cancer incidence between social groups vary by age [15,16]. This is likely to relate to variations in risk factor distribution in social groups over time (a cohort effect) as well as certain risk factors having a differential effect by age. "
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    ABSTRACT: Breast cancer incidence varies between social groups, but differences have not been thoroughly examined in New Zealand. The objectives of this study are to determine whether trends in breast cancer incidence varied by ethnicity and socioeconomic position between 1981 and 2004 in New Zealand, and to assess possible risk factor explanations. Five cohorts of the entire New Zealand population for 1981-86, 1986-1991, 1991-1996, 1996-2001, and 2001-2004 were created, and probabilistically linked to cancer registry records, allowing direct determination of ethnic and socioeconomic trends in breast cancer incidence. Breast cancer rates increased across all ethnic and socioeconomic groups between 1981 and 2004. Māori women consistently had the highest age standardised rates, and the difference between Māori and European/Other women increased from 7% in 1981-6 to 24% in 2001-4. Pacific and Asian women had consistently lower rates of breast cancer than European/Other women over the time period studied (12% and 28% lower respectively when pooled over time), although young Pacific women had slightly higher incidence rates than young European/other women. A gradient between high and low income women was evident, with high income women having breast cancer rates approximately 10% higher and this difference did not change significantly over time. Differences in breast cancer incidence between European and Pacific women and between socioeconomic groups are explicable in terms of known risk factors. However no straightforward explanation for the relatively high incidence amongst Māori is apparent. Further research to explore high Māori breast cancer rates may contribute to reducing the burden of breast cancer amongst Māori women, as well as improving our understanding of the aetiology of breast cancer.
    BMC Cancer 12/2010; 10(1):674. DOI:10.1186/1471-2407-10-674 · 3.36 Impact Factor
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