title: Elevated risk of chronic lymphocytic leukemia and other indolent non-Hodgkin's lymphomas among relatives of patients with chronic lymphocytic leukemia.
abstract: BACKGROUND
  Previous studies have shown increased familial risk for chronic lymphocytic leukemia. In the most comprehensive study to date, we evaluated risk of chronic lymphocytic leukemia and lymphoproliferative disorders among first-degree relatives of chronic lymphocytic leukemia cases compared to first-degree relatives of controls.
  
  
  METHODS
  Population-based registry data from Sweden were used to evaluate outcomes in 26,947 first-degree relatives of 9,717 chronic lymphocytic leukemia patients (diagnosed 1958-2004) compared with 107,223 first-degree relatives of 38,159 matched controls. Using a marginal survival model, we calculated relative risks (RR) and 95% confidence intervals as measures of familial aggregation.
  
  
  RESULTS
  Compared to relatives of controls, relatives of chronic lymphocytic leukemia patients had an increased risk for chronic lymphocytic leukemia (RR=8.5, 6.1-11.7) and other non-Hodgkin's lymphomas (NHLs) (RR=1.9, 1.5-2.3). Evaluating NHL subtypes, we found a striking excess of indolent B-cell NHL, specifically lymphoplasmacytic lymphoma/Waldenström macroglobulinemia and hairy cell leukemia. No excesses of aggressive B-cell or T-cell lymphomas were found. There was no statistical excess of Hodgkin's lymphoma, multiple myeloma, or the precursor condition, monoclonal gammopathy of undetermined significance, among chronic lymphocytic leukemia relatives.
  
  
  CONCLUSIONS
  These familial aggregations are striking and provide novel clues to research designed to uncover early pathogenetic mechanisms in chronic lymphocytic leukemia including studies to identify germ line susceptibility genes. However, clinicians should counsel their chronic lymphocytic leukemia patients emphasizing that because the baseline population risks are low, the absolute risk for a first-degree relative to develop chronic lymphocytic leukemia or another indolent lymphoma is low. At this time, an increased medical surveillance of first-degree relatives of chronic lymphocytic leukemia patients has no role outside research studies.
authors.affiliation: Genetic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 6120 Executive Blvd., Bethesda, MD 20892, USA. goldinl@mail.nih.gov
authors.forename: Lynn R
authors.initials: LR
authors.lastname: Goldin
authors.forename: Magnus
authors.initials: M
authors.lastname: Björkholm
authors.forename: Sigurdur Y
authors.initials: SY
authors.lastname: Kristinsson
authors.forename: Ingemar
authors.initials: I
authors.lastname: Turesson
authors.forename: Ola
authors.initials: O
authors.lastname: Landgren
mesh_terms: D000368:Aged; D005190:Family; D005192:Family Health; D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000453:epidemiology / Q000235:genetics*; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D012042:Registries / Q000706:statistics & numerical data; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology