title: Incidence and outcomes of contralateral breast cancers.
abstract: BACKGROUND
  The significance of a contralateral breast cancer is largely unknown, making prophylactic mastectomy controversial.
  
  
  METHODS
  Differences between stages of initial and contralateral cancers were determined by t test. Survival distributions were compared by log-rank analyses and compared with Surveillance Epidemiology and End Results data for unilateral cancers.
  
  
  RESULTS
  Metachronous contralateral cancers occurred at a rate of .13% per year and were of significantly lower stage. Metachronous cancers adversely impacted survival for patients with low-stage initial cancers, but the interval between cancers was less than 36 months. Synchronous tumors occurred in 2.3% of patients; survival was worse than for patients with metachronous cancers.
  
  
  CONCLUSIONS
  Prophylactic mastectomy is unlikely to be beneficial because of the lower stages and low incidence of second cancers, even for patients with initial low-stage cancers.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Glenda
authors.initials: G
authors.lastname: Quan
authors.forename: SuEllen J
authors.initials: SJ
authors.lastname: Pommier
authors.forename: Rodney F
authors.initials: RF
authors.lastname: Pommier
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology / Q000517:prevention & control; D005260:Female; D006801:Humans; D015994:Incidence; D008408:Mastectomy; D008875:Middle Aged; D009367:Neoplasm Staging; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology / Q000517:prevention & control; D011379:Prognosis; D018570:Risk Assessment; D018426:SEER Program; D016019:Survival Analysis