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.
CancerSpectrum Knowledge Environment (Impact Factor: 15.16). 01/2009; 100(24):1804-14. DOI: 10.1093/jnci/djn411
Source: PubMed

ABSTRACT 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.


Available from: Idan Menashe, Jun 03, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to determine if race is a factor on overall survival when stage at diagnosis is compared. In this study, a total of 93 women with triple negative breast cancer (TNBC) were evaluated for survival outcomes after diagnosis between the year 2000 through 2010. Thirty-five patients (38%) were African American (AA), and 58 patients (62%) were Caucasian. Overall survival rates were estimated using the Kaplan-Meier method and compared between groups using the log-rank test. Student's t-test was used to calculate differences in cancer recurrence and mortality rates by stage and race. Cox proportional hazards ratios were used to determine the association of patient and variables with clinical outcome. Of women diagnosed with stage 1 breast cancer, the overall survival rates for AAs was 100% compared to Caucasians at 94% (95% CI, 0.003 to 19; P = 0.5). For women with stage 2 breast cancer, overall survival for AA women was 85% and for Caucasian women was 86% (HR = 0.8; 95% CI, 0.3 to 2.6; P = 0.73). For advanced stages (stage 3 and 4), survival for AA women were 78% and 40% for Caucasian women (HR = 0.6; 95% CI 0.2 to 1.98; P = 0.43). Rates of recurrence and mortality were not significantly different between AA and Caucasian TNBC patients. After controlling for patient variables, race was not significantly associated with OS (HR = 1.24; 95% CI, 0.32 to 5.08; P = 0.74) when comparing AA to Caucasian patients. Our study suggests that race does not have an effect on overall survival in African American and Caucasian women diagnosed with TNBC in Arkansas.
    SpringerPlus 01/2013; 2(1):516. DOI:10.1186/2193-1801-2-516
  • [Show abstract] [Hide abstract]
    ABSTRACT: Breast cancer risk prediction models have underestimated risk for African American women, contributing to lower recruitment rates in prevention trials. A model previously developed for African American women was found to underestimate risk in the Black Women's Health Study (BWHS). We developed a breast cancer risk model for African American women using relative risks derived from 10 years of follow-up of BWHS participants age 30 to 69 years at baseline. Using the subsequent 5 years of follow-up data, we evaluated calibration as the ratio of expected to observed number of breast cancers and assessed discriminatory accuracy using the concordance statistic. The BWHS model included family history, previous biopsy, body mass index at age 18 years, age at menarche, age at first birth, oral contraceptive use, bilateral oophorectomy, estrogen plus progestin use, and height. There was good agreement between predicted and observed number of breast cancers overall (expected-to-observed ratio, 0.96; 95% CI, 0.88 to 1.05) and in most risk factor categories. Discriminatory accuracy was higher for women younger than age 50 years (area under the curve [AUC], 0.62; 95% CI, 0.58 to 0.65) than for women age ≥ 50 years (AUC, 0.56; 95% CI, 0.53 to 0.59). Using a 5-year predicted risk of 1.66% or greater as a cut point, 2.8% of women younger than 50 years old and 32.2% of women ≥ 50 years old were classified as being at elevated risk of invasive breast cancer. The BWHS model was well calibrated overall, and the predictive ability was best for younger women. The proportion of women predicted to meet the 1.66% cut point commonly used to determine eligibility for breast cancer prevention trials was greatly increased relative to previous models. © 2015 by American Society of Clinical Oncology.
    Journal of Clinical Oncology 01/2015; 33(9). DOI:10.1200/JCO.2014.57.2750 · 17.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Younger ages at diagnosis for blacks compared with whites have been reported for several cancer types. However, the US black population is younger than the white population, which may bias age comparisons that do not account for the populations at risk. We analyzed Surveillance, Epidemiology, and End Results data for non-Hispanic blacks and non-Hispanic whites from 18 regions for the year 2010. We calculated crude mean ages at diagnosis among cases of 29 cancer types for whites and blacks. Separately, we calculated adjusted means that corrected for differences in population structure, which we obtained by fitting linear regression models to the ages at diagnosis with statistical weights specific to age and sex. Negative differences indicate younger ages in blacks, while positive differences indicate older ages in blacks. All statistical tests were two-sided. Based on crude means, blacks were diagnosed at younger ages than whites for nearly every cancer type. However, adjustment for population structure shifted the comparisons toward older ages among blacks, and only six statistically significant differences of three or more years remained. Blacks were younger than whites at diagnosis for Kaposi sarcoma (-10.2 years), male soft tissue cancer (-5.6), male anal cancer (-5.5), and non-Hodgkin's lymphoma (-3.7), but older for cervical cancer (+4.7 years) and female thyroid cancer (+3.3). Smaller differences (<3 years) were present for female breast, female colon, lung, pancreas, prostate, and uterine corpus cancers (all P ≤ .001). Most differences between blacks and whites in the age at cancer diagnosis are small. Large differences for a few cancer types may be driven by etiologic and subtype heterogeneity as well as disparities in access to care. © Published by Oxford University Press 2015.
    JNCI Journal of the National Cancer Institute 03/2015; 107(3). DOI:10.1093/jnci/dju489 · 15.16 Impact Factor