title: Impact of mammographic screening on ethnic and socioeconomic inequities in breast cancer stage at diagnosis and survival in New Zealand: a cohort study.
abstract: BACKGROUND
  Indigenous Māori women experience a 60% higher breast cancer mortality rate compared with European women in New Zealand. We explored the impact of differences in rates of screen detected breast cancer on inequities in cancer stage at diagnosis and survival between Māori and NZ European women.
  
  
  METHODS
  All primary breast cancers diagnosed in screening age women (as defined by the New Zealand National Breast Cancer Screening Programme) during 1999-2012 in the Waikato area (n = 1846) were identified from the Waikato Breast Cancer Register and the National Screening Database. Stage at diagnosis and survival were compared for screen detected (n = 1106) and non-screen detected (n = 740) breast cancer by ethnicity and socioeconomic status.
  
  
  RESULTS
  Indigenous Māori women were significantly more likely to be diagnosed with more advanced cancer compared with NZ European women (OR = 1.51), and approximately a half of this difference was explained by lower rate of screen detected cancer for Māori women. For non-screen detected cancer, Māori had significantly lower 10-year breast cancer survival compared with NZ European (46.5% vs. 73.2%) as did most deprived compared with most affluent socioeconomic quintiles (64.8% vs. 81.1%). No significant survival differences were observed for screen detected cancer by ethnicity or socioeconomic deprivation.
  
  
  CONCLUSIONS
  The lower rate of screen detected breast cancer appears to be a key contributor towards the higher rate of advanced cancer at diagnosis and lower breast cancer survival for Māori compared with NZ European women. Among women with screen-detected breast cancer, Māori women do just as well as NZ European women, demonstrating the success of breast screening for Māori women who are able to access screening. Increasing breast cancer screening rates has the potential to improve survival for Māori women and reduce breast cancer survival inequity between Māori and NZ European women.
authors: Waikato Clinical School, University of Auckland, Auckland, New Zealand. Sanjeewa.Seneviratne@waikatodhb.health.nz.|Department of Surgery, University of Colombo, Colombo, Sri Lanka. Sanjeewa.Seneviratne@waikatodhb.health.nz.|Breast Cancer Research Office, Waikato Hospital, PO Box 934, Hamilton, 3240, New Zealand. Sanjeewa.Seneviratne@waikatodhb.health.nz.
authors: Sanjeewa
authors: S
authors: Seneviratne
authors: Waikato Clinical School, University of Auckland, Auckland, New Zealand. Ian.Campbell@waikatodhb.health.nz.
authors: Ian
authors: I
authors: Campbell
authors: Māori Health Services, Waikato District Health Board, Hamilton, New Zealand. Nina.Scott@waikatodhb.health.nz.
authors: Nina
authors: N
authors: Scott
authors: Waikato Breast Cancer Trust, Waikato Hospital, Hamilton, New Zealand. Rachel.Shirley@waikatodhb.health.nz.
authors: Rachel
authors: R
authors: Shirley
authors: Waikato Clinical School, University of Auckland, Auckland, New Zealand. Ross.Lawrenson@waikatodhb.health.nz.
authors: Ross
authors: R
authors: Lawrenson
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000401:mortality* / Q000473:pathology; D015331:Cohort Studies; D055088:Early Detection of Cancer / Q000706:statistics & numerical data; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D012720:Severity of Illness Index; D012923:Social Class; D012959:Socioeconomic Factors; D016019:Survival Analysis
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