Epidemiology of Breast Cancer

  • Demographics, incidence and mortality:
    • In 2018:
      • An estimated 2.1 million women were newly diagnosed with breast cancer:
        • Approximately one new case diagnosed every 18 seconds
      • Additionally, 626,679 women with breast cancer died
    • The global incidence of breast cancer:
      • Has been rising:
        • With annual increases of 3.1%:
          • Beginning with 641,000 cases in 1980 and increasing to greater than 1.6 million in 2010:
            • This trend is likely to continue
      • Indeed, the global cancer burden in women:
        • Is increasing in countries regardless of income level:
          • Owing to population growth and an aging population
      • The female population:
        • Accounts for 49.5% of the global population:
          • They form a larger proportion of the population > 60 years of age
        • Furthermore, the epidemiology of advanced breast cancer is a research priority as, in most countries:
          • The number of patients with advanced disease is unknown
        • Cancer registries mostly track diagnosis and deaths but not relapses
        • One study estimated that, in 2017:
          • ~160,000 patients live with advanced-stage breast cancer in the United States alone5
        • The death rates also vary among subtypes of breast cancer:
          • With HER2-positive disease:
            • Associated with a higher death rate:
              • Followed by the TNBC, luminal A and luminal B subtypes
    • Incidence varies worldwide:
      • With higher incidence in high-income regions (92 per 100,000 in North America) than in lower income regions (27 per 100,000 in middle Africa and eastern Asia):
        • These patterns reflect both:
          • The risk factors and the availability and utility of mammography (and, therefore, detected breast cancers)
        • The highest breast cancer incidence is in:
          • North America
          • Australia
          • New Zealand
          • Northern and western Europe
      • Furthermore, in high-income countries:
        • Breast cancer is often diagnosed at an early stage and the prognosis is usually good
      • However, in low- and middle- income countries:
        • Breast cancer is often diagnosed at a later stage:
          • And is accordingly, associated with poorer survival:
            • A fact that is reflected in the mortality statistics
        • Breast cancer mortality is usually higher in many low- and middle-income countries:
          • Such as those in sub-Saharan Africa and developing Asian countries:
            • Despite their lower incidence:
              • Due to delayed presentation, late stage at diagnosis and limited access to treatment
      • Several studies have also shown that breast cancer presents:
        • Earlier in Asian women (typically 40 to 50 years of age) than in their western counterparts (typically 60 to 70 years of age)
      • In addition, patients in developing countries who are diagnosed with breast cancer:
        • Are roughly 10 years younger than those in developed countries:
          • The proportion of young patients ( less than 35 years of age) varies from:
            • ~10% in developed countries to up to 25% in developing Asian countries
      • The biology of the tumor also varies by ethnicity:
        • Which has implications for the difference in mortality:
          • African and African-American women:
            • Have the highest rates of TNBC compared with any other ethnic group
            • They also had higher rates of metastatic disease
            • They have the highest rates of poorly differentiated or undifferentiated grade among all subtypes:
              • All of which are associated with lower survival
          • Additionally, metastatic breast cancer represents 9% of diagnoses among non-Hispanic black women:
            • Compared with 5% to 6% of diagnoses in other ethnic groups
          • Regarding the survival gains in patients with advanced disease during the years 1975 to 2013:
            • The 5-year cause-specific survival of non-Hispanic white women was higher than that of other ethnic groups:
              • Particularly non-Hispanic black women (19% to 37% com- pared with 16% to 26%):
                • This pattern is multifactorial and involves genetic predisposition, lifestyle and other environmental factors
  • References:
    • Bray, F. et al. Cancer Incidence in Five Continents: inclusion criteria, highlights from Volume X and the global status of cancer registration. Int. J. Cancer 137, 2060–2071 (2015).
    • Mariotto, A. B., Etzioni, R., Hurlbert, M., Penberthy, L. & Mayer, M. Estimation of the number of women living with metastatic breast cancer in the United States. Cancer Epidemiol. Biomark. Prev. 26, 809–815 (2017).
    • Ren, J.-X., Gong, Y., Ling, H., Hu, X. & Shao, Z.-M. Racial/ethnic differences in the outcomes of patients with metastatic breast cancer: contributions of demographic, socioeconomic, tumor and metastatic characteristics. Breast Cancer Res. Treat. 173, 225–237 (2019).
    • Torre, L. A., Siegel, R. L., Ward, E. M. & Jemal, A. Global cancer incidence and mortality rates and trends — an update. Cancer Epidemiol. Biomark. Prev. 25, 16–27 (2016).
    • Ginsburg, O. et al. The global burden of women’s cancers: a grand challenge in global health. Lancet 389, 847–860 (2017).
    • Allemani, C. et al. Global surveillance of cancer survival 1995–2009: analysis of individual data for 25 676 887 patients from 279 population-based registries in 67 countries (CONCORD-2). Lancet 385, 977–1010 (2015).
    • Winters, S., Martin, C., Murphy, D. & Shokar, N. K. Breast cancer epidemiology, prevention, and screening. Prog. Mol. Biol. Transl Sci. 151, 1–32 (2017).
    • Hossain, M. S., Ferdous, S. & Karim-Kos, H. E. Breast cancer in South. Asia: a Bangladeshi perspective. Cancer Epidemiol. 38, 465–470 (2014).
    • Leong, S. P. L. et al. Is breast cancer the same disease in Asian and western countries? World J. Surg. 34, 2308–2324 (2010).
    • Bhoo Pathy, N. et al. Breast cancer in a multi-ethnic Asian setting: results from the Singapore–Malaysia hospital-based breast cancer registry. Breast 20, S75–S80 (2011).
    • Raina, V. et al. Clinical features and prognostic factors of early breast cancer at a major cancer center in North India. Indian J. Cancer 42, 40 (2005).
    • Agarwal, G., Pradeep, P. V., Aggarwal, V., Yip, C.-H. & Cheung, P. S. Y. Spectrum of breast cancer in Asian women. World J. Surg. 31, 1031–1040 (2007).
    • Li, C. I., Malone, K. E. & Daling, J. R. Differences in breast cancer hormone receptor status and histology by race and ethnicity among women 50 years of age and older. Cancer Epidemiol. Biomark. Prev. 11, 601–607 (2002).
    • Wong, F. Y., Tham, W. Y., Nei, W. L., Lim, C. & Miao, H. Age exerts a continuous effect in the outcomes of Asian breast cancer patients treated with breast- conserving therapy. Cancer Commun. 38, 39 (2018).
    • Kohler, B. A. et al. Annual report to the nation on the status of cancer, 1975–2011, featuring incidence of breast cancer subtypes by race/ethnicity, poverty, and state. J. Natl Cancer Inst107, https://doi.org/ 10.1093/jnci/djv048 (2015).
    • DeSantis, C. E. et al. Breast cancer statistics, 2015: Convergence of incidence rates between black and white women: Breast Cancer Statistics, 2015.
    • CA Cancer J. Clin. 66, 31–42 (2016).
    • DeSantis, C. E., Ma, J., Goding Sauer, A., Newman, L. A. & Jemal, A. Breast cancer statistics, 2017, racial disparity in mortality by state: Breast Cancer Statistics, 2017. CA Cancer J. Clin. 67, 439–448 (2017).

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