title: Dilemma in multifocal breast cancer – largest versus  aggregate diameter.
abstract: BACKGROUND
  Several studies have shown that multifocal breast cancer has higher risks of lymph node metastases compared to unifocal cancer. This has a significant impact on prognosis and treatment options. We investigated whether this was true in our institution.
  
  
  METHODS
  This was a retrospective study involving 75 patients with multifocal breast cancer from the year 2000 to 2007. The data recorded were largest, aggregate and extent diameter, and outcomes measured were lymph node metastases, disease recurrence and mortality rate.We randomly selected 77 age-matched subjects with unifocal cancer from the same time period for comparison.
  
  
  RESULTS
  The average age was 57 and 58 years for the unifocal and multifocal groups, respectively. In the multifocal group, there were 54.6% ductal, 26.7% lobular and 17.3% mixed/other cancers. The unifocal group consisted of 84.4% ductal, 6.5% lobular and 9.1% mixed/other cancers. In the multifocal group, largest diameter was available for 74 patients averaging 22.1 mm. The average diameter in unifocal cancer was 18.4 mm. Fifty-two per cent of the multifocal subjects had positive lymph nodes compared with 36% in the unifocal group.
  
  
  CONCLUSIONS
  Our data showed that multifocality was associated with a higher rate of lymph node metastases. This might indicate that multifocal breast cancer reflected a heavier disease burden than unifocal cancer and should be treated more aggressively.
authors.affiliation: The Breast and Endocrine Surgical Unit, The Queen Elizabeth Hospital, Australia. leongung@gmail.com
authors.forename: Leong Ung
authors.initials: LU
authors.lastname: Tiong
authors.forename: Robert
authors.initials: R
authors.lastname: Parkyn
authors.forename: David
authors.initials: D
authors.lastname: Walters
authors.forename: John
authors.initials: J
authors.lastname: Field
authors.forename: Christine
authors.initials: C
authors.lastname: Lai
authors.forename: David C A
authors.initials: DC
authors.lastname: Walsh
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000473:pathology* / Q000601:surgery; D018275:Carcinoma, Lobular / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008207:Lymphatic Metastasis; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies