title: Survival after bilateral breast cancer: results from a population-based study.
abstract: BACKGROUND
  Controversy exists on the impact of bilaterality of breast cancer on survival. We used population-based data to compare survival of women with unilateral versus bilateral breast cancer.
  
  
  METHODS
  At the Geneva cancer registry, we identified all 7,912 women diagnosed with invasive breast cancer between 1970 and 2002. Breast cancers were categorized as unilateral, synchronous bilateral (contralateral tumour diagnosed within six months after the first tumour) and metachronous bilateral (contralateral tumour diagnosed over six months after the first tumour). With multivariate modelling we compared characteristics and survival between women with unilateral and bilateral disease.
  
  
  RESULTS
  Patients with synchronous bilateral tumours (n = 155, 2.0%) had more often lobular histology and less frequently stage I disease than women with unilateral disease. Women with metachronous breast cancer (n = 219, 2.8%) received less often chemotherapy or hormone therapy for their first tumours. Ten-year disease-specific survival was similar (66%) after unilateral and metachronous bilateral breast cancer, but worse after synchronous bilateral cancer (51%). After adjustment, breast cancer mortality risks were not significantly increased for women with either synchronous or metachronous bilateral disease (Hazard ratios 1.1 (0.8-1.5) and 0.8 (0.5-1.4), respectively).
  
  
  CONCLUSIONS
  This large population-based study indicates that bilaterality of breast cancer is not associated with impaired survival.
authors.affiliation: Geneva Cancer Registry, Institute for Social and Preventive Medicine, Geneva University, 55 bd de la Cluse, CH-1205, Geneva, Switzerland. cofhmv@nus.edu.sg
authors.forename: Helena M
authors.initials: HM
authors.lastname: Verkooijen
authors.forename: Vanessa
authors.initials: V
authors.lastname: Chatelain
authors.forename: Gérald
authors.initials: G
authors.lastname: Fioretta
authors.forename: Georges
authors.initials: G
authors.lastname: Vlastos
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Rapiti
authors.forename: André-Pascal
authors.initials: AP
authors.lastname: Sappino
authors.forename: Christine
authors.initials: C
authors.lastname: Bouchardy
authors.forename: Pierre O
authors.initials: PO
authors.lastname: Chappuis
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D015996:Survival Rate