title: Breast cancer: trends in international incidence in men and women.
abstract: BACKGROUND
  The age-standardised incidence of breast cancer varies geographically, with rates in the highest-risk countries more than five times those in the lowest-risk countries.
  
  
  METHODS
  We investigated the correlation between male (MBC) and female breast cancer (FBC) incidence stratified by female age-group (<50 years, and ≥50 years) and used Poisson regression to examine male incidence rate ratios according to female incidence rates.
  
  
  RESULTS
  Age-adjusted breast cancer incidence rates for males and females share a similar geographic distribution (Spearman's correlation=0.51; P<0.0001). A correlation with male incidence rates was found for the entire female population and for women aged 50 years and over. Breast cancer incidence rates in males aged <50 years were not associated with FBC incidence, whereas those in males aged 50 years were. MBC incidence displays a small 'hook' similar to the Clemmesen's hook for FBC, but at a later age than the female hook.
  
  
  CONCLUSIONS
  Further investigation of possible explanations for these patterns is warranted. Although the incidence of breast cancer is much lower in men than in women, it may be possible to identify a cause common to both men and women.
authors: Department of Public Health Science, School of Public Health, University of Alberta 3-381 Edmonton Clinic Health Academy, 11405 87th Avenue, Edmonton Alberta T6G 1C9, Canada.
authors: E
authors: E
authors: Kreiter
authors: Wayne Francis Cancer Epidemiology Research Group, School of Health Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
authors: A
authors: A
authors: Richardson
authors: Public Health Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, M4B402, Seattle, WA 98109, USA.
authors: J
authors: J
authors: Potter
authors: Department of Public Health Science, School of Public Health, University of Alberta 3-381 Edmonton Clinic Health Academy, 11405 87th Avenue, Edmonton Alberta T6G 1C9, Canada.
authors: Y
authors: Y
authors: Yasui
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology*; D018567:Breast Neoplasms, Male / Q000453:epidemiology*; D005260:Female; D005843:Geography; D014943:Global Health / Q000639:trends*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged