title: Time trends in breast cancer and menopause hormone therapy use in New Zealand.
abstract: OBJECTIVE
  The publication of preliminary findings from the Women's Health Initiative (WHI) Study in 2002 suggested an increased risk of breast cancer among users of menopause hormone therapy (MHT). This resulted world-wide in a rapid and significant decline in the use of hormone therapy. It was later claimed that breast cancer incidence rates had fallen as a result of lower rates of hormone therapy use. Our aim was to investigate whether there was an association between changes in the use of hormone therapy and rates of breast cancer diagnosis in New Zealand subsequent to the publication of the WHI.
  
  
  METHODS
  Validated prescription usage data along with breast cancer screening and cancer registration data were accessed. Time trends extending for 8 years after the publication of the WHI were assessed.
  
  
  RESULTS
  The use of hormone therapy for managing menopausal symptoms fell by about 70% following the controversy about its safety. Breast cancer registration rates among women aged 50-59 years had started to fall in advance of this change in prescribing. Changes in other age groups appear to coincide with changes in the screening eligibility for the national breast screening program rather than use of hormone therapy.
  
  
  CONCLUSIONS
  The time trend analysis does not support an association between changes in hormone therapy use and the incidence rate of breast cancer.
authors.affiliation: a Emeritus Professor of Epidemiology, University of Surrey , UK ;
authors.forename: R
authors.initials: R
authors.lastname: Farmer
authors.affiliation: b Christchurch Women's Hospital , Christchurch , New Zealand.
authors.forename: A
authors.initials: A
authors.lastname: Fenton
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology*; D015914:Estrogen Replacement Therapy / Q000009:adverse effects / Q000706:statistics & numerical data* / Q000639:trends*; D005260:Female; D006801:Humans; D015994:Incidence; D008403:Mass Screening; D008593:Menopause / Q000187:drug effects*; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D016387:Women's Health; D055815:Young Adult
keywords: Breast cancer; New Zealand; hormone therapy