title: Racial comparison of receptor-defined breast cancer in Southern African women: subtype prevalence and age-incidence analysis of nationwide cancer registry data.
abstract: BACKGROUND
  Receptor-defined breast cancer proportions vary across Africa. They have important implications for survival prospects and research priorities.
  
  
  METHODS
  We studied estrogen receptor (ER), progesterone receptor (PR), and HER2 receptor statuses in two multiracial Southern African countries with routine diagnostic immunohistochemistry. A total of 12,361 women with histologically confirmed breast cancer diagnosed at age ≥20 years during (i) 2009-2011 from South Africa's national cancer registry (public sector) and (ii) 2011-2013 from Namibia's only cancer hospital were included. Crude, age, and age + laboratory-adjusted ORs of receptor status were analyzed using logistic regression, and age-incidence curves were analyzed using Poisson regression.
  
  
  RESULTS
  A total of 10,047 (81%) women had known ER status. Ranking of subtypes was consistent across races: ER(+)/PR(+)HER2(-) was most common (race-specific percentage range, 54.6%-64.8%), followed by triple-negative (17.4%-21.9%), ER(+)/PR(+)HER2(+) (9.6%-13.9%), and ER(-)PR(-)HER2(+) (7.8%-10.9%). Percentages in black versus white women were 33.8% [95% confidence (CI), 32.5-35.0] versus 26.0% (24.0-27.9) ER(-); 20.9% (19.7-22.1) versus 17.5% (15.4-19.6) triple-negative; and 10.7% (9.8-11.6) versus 7.8% (6.3-9.3) ER(-)PR(-)HER2(+). Indian/Asian and mixed-ancestry women had intermediate values. Age-incidence curves had similar shapes across races: rates increased by 12.7% per year (12.2-13.1) across ER subtypes under the age of 50 years, and thereafter slowed for ER(+) (1.95%) and plateaued for ER(-) disease (-0.1%).
  
  
  CONCLUSIONS
  ER(+) breast cancer dominates in all Southern African races, but black women have a modest excess of aggressive subtypes.
  
  
  CONCLUSIONS
  On the basis of the predominant receptor-defined breast tumors in Southern Africa, improving survival for the growing breast cancer burden should be achievable through earlier diagnosis and appropriate treatment.
authors.affiliation: Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France. Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Caroline
authors.initials: C
authors.lastname: Dickens
authors.affiliation: Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Raquel
authors.initials: R
authors.lastname: Duarte
authors.affiliation: Windhoek Central Hospital, Windhoek, Namibia.
authors.forename: Annelle
authors.initials: A
authors.lastname: Zietsman
authors.affiliation: Department of Surgery, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. Chris Hani Baragwanath Academic Hospital, Soweto, South Africa.
authors.forename: Herbert
authors.initials: H
authors.lastname: Cubasch
authors.affiliation: National Cancer Registry of South Africa, National Health and Laboratory Services, Johannesburg, South Africa.
authors.forename: Patricia
authors.initials: P
authors.lastname: Kellett
authors.affiliation: Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France.
authors.forename: Joachim
authors.initials: J
authors.lastname: Schüz
authors.affiliation: National Cancer Registry of South Africa, National Health and Laboratory Services, Johannesburg, South Africa.
authors.forename: Danuta
authors.initials: D
authors.lastname: Kielkowski
authors.affiliation: Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France. mccormackv@iarc.fr.
authors.forename: Valerie
authors.initials: V
authors.lastname: McCormack
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data; D044383:Black People / Q000706:statistics & numerical data; D001943:Breast Neoplasms / Q000737:chemistry* / Q000208:ethnology*; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009276:Namibia / Q000453:epidemiology; D015995:Prevalence; D044469:Racial Groups / Q000706:statistics & numerical data*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D013019:South Africa / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human