Epidemiology of breast cancer among young black women and the rise in young-onset distant disease in the U.S. Public Deposited

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  • March 19, 2019
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  • Chollet Hinton, Lynn
    • Affiliation: Gillings School of Global Public Health, Department of Epidemiology
Abstract
  • Purpose: Rates of distant (stage IV) breast cancer have significantly increased since 1976 among young women <40 years. Young-onset breast cancers tend to be more aggressive with poorer prognosis than older-onset disease, particularly among black women. This dissertation sought to clarify the impact of shifting incidence by (1) characterizing the epidemiology of young black women’s breast cancer, and (2) investigating temporal shifts in breast cancer biology and diagnostic imaging use as contributors to rising young-onset distant disease. Methods: We examined tumor characteristics and breast cancer risk factors associated with premenopausal young (<40) vs. older (≥40) black women’s breast cancer in the African American Breast Cancer Epidemiology and Risk Consortium (2,008 cases; 5,144 controls) using unconditional logistic regression. Additionally, we examined longitudinal breast cancer incidence using joinpoint regression among young women (20-39 years) from 1992-2011 according to breast tumor characteristics in the Surveillance, Epidemiology, and End Results (SEER) program. Temporal patterns in imaging use (positron emission tomography, computed tomography, magnetic resonance imaging, bone scans) were examined separately among Medicare-eligible breast cancer cases using SEER-Medicare-linked data. Results: Premenopausal black women <40 years had higher frequency of poorer-prognostic tumor characteristics compared to older (≥40) women, including negative estrogen and progesterone receptor (ER/PR) status, triple-negative subtype, high grade, higher stage, and larger tumor size. Adiposity, family history of breast cancer, and oral contraceptive use were associated with increased risk for young women while breastfeeding was more strongly protective. In SEER, the frequency of favorable tumor characteristics significantly increased while less favorable characteristics declined among young women. Imaging use dramatically increased from 1992-2011 among SEER-Medicare cases and was significantly associated with less favorable characteristics, including ER/PR negativity, high grade, and tumor size >2cm. Conclusions: Among premenopausal black women, young age (<40 years) was associated with more aggressive breast tumor biology. Modifiable risk factors including breastfeeding, adiposity, and oral contraceptive use may be important targets for mitigating harms of young-onset breast cancer. In SEER, the frequency of aggressive disease decreased while imaging use dramatically increased from 1992-2011, suggesting that stage migration rather than shifting tumor biology has contributed to rising incidence of young-onset distant breast cancer.
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  • In Copyright
Advisor
  • Olshan, Andrew
  • Troester, Melissa
  • Anders, Carey
  • Nichols, Hazel
  • Lund, Jennifer
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017
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