title: Prognostic information of a previously diagnosed sister is an independent prognosticator for a newly diagnosed sister with breast cancer.
abstract: BACKGROUND
  Breast cancer survival has been shown to be associated among relatives. In this study, we used a population-based cohort of Swedish sisters, both diagnosed with breast cancer, to determine whether prognostic information of a previously diagnosed sibling is useful for the clinical management of a newly diagnosed sibling.
  
  
  METHODS
  The population-based cohort included all sister pairs, 1617 sisters, diagnosed with breast cancer in Sweden, from 1 January 1992, through 31 December 2006, with complete follow-up. All information was collected manually from original pathology reports and patient records. The Kappa statistic was used to measure the agreement of primary tumor characteristics between the sisters. We modeled the breast cancer-specific survival using multivariate (Cox) proportional hazard analyses in two steps categorizing the older sister's survival.
  
  
  RESULTS
  Estrogen receptor status was the only tumor characteristic significantly associated between the sisters [κ 0.18 (95% confidence interval (CI) 0.089-0.27)]. Younger sisters with poor older sister survival showed significantly worse survival compared with patients with good older sister survival (log rank, P = 0.017). A twofold increased hazard ratio (HR) for death from breast cancer was found in younger sisters with poor older sister survival compared with patients with good sister survival [HR 2.56 (95% CI 1.16-5.65)], adjusting for age and calendar period of diagnosis, socioeconomic factors, number of children and hospital of primary tumor diagnosis. When further adjusting for primary tumor characteristics and adjuvant therapy, the risk for death from breast cancer in younger sisters with poor older sister survival became more pronounced [HR 3.35 (1.34-8.34)].
  
  
  CONCLUSIONS
  Our findings derived from a population-based cohort of Swedish sister pairs suggest that breast cancer-specific survival is inherited independent of tumor characteristics and treatment in the sibling later diagnosed with the disease. Prognostic information of a previously diagnosed sibling with breast cancer could be important in the clinical management.
authors: Department of Surgery, University of California at San Francisco (UCSF), San Francisco, USA; Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden. Electronic address: linda.lindstrom@ki.se.
authors: L S
authors: LS
authors: Lindström
authors: Division of Human Genetics, Genome Institute of Singapore; Department of Epidemiology and Public Health, National University of Singapore, Singapore.
authors: J
authors: J
authors: Li
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm.
authors: M
authors: M
authors: Lee
authors: Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors: Z
authors: Z
authors: Einbeigi
authors: Department of Surgery, Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore.
authors: M
authors: M
authors: Hartman
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm.
authors: P
authors: P
authors: Hall
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm.
authors: K
authors: K
authors: Czene
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D035781:Siblings; D016019:Survival Analysis; D013548:Sweden; D044465:White People
keywords: breast cancer; familial cancer survival; inherited prognosis; population-based; prognosis; sister study