title: Blood transfusions and the subsequent risk of hematologic malignancies.
abstract: BACKGROUND
  Blood transfusions are associated with viral transmission and immunomodulation, perhaps increasing subsequent risk of hematologic malignancies (HMs). Prior studies of transfusion recipients have lacked details on specific HM subtypes.
  
  
  METHODS
  Risk of HM after blood transfusion was evaluated in a US population-based case-control study (77,488 elderly HM cases identified through cancer registries, 154,509 controls). Transfusions were identified using linked Medicare hospitalization claims. Polytomous logistic regression was used to calculate odds ratios (ORs) associating transfusion and HM subtypes by features suggestive of a causal relationship.
  
  
  RESULTS
  A history of transfusion was present in 7.9% of HM cases versus 5.9% of controls. Associations for most HM subtypes suggested reverse causality: ORs were elevated only during the shortest latency periods; ORs for unspecified anemia and gastrointestinal bleeding, which may be related to undiagnosed HM, were stronger than for surgeries, which are unlikely to be related to HM; and/or there was no dose response. In contrast, risk for lymphoplasmacytic lymphoma (1397 cases) was elevated at long latency (OR, 1.56 at 10+ years after transfusion), after transfusions related to surgeries (OR, 1.22-1.47), and in a dose-response relationship with number of transfusion-related hospitalizations (OR, 1.53 with one hospitalization; OR, 1.80 with two or more hospitalizations, p trend < 0.0001). Risk for marginal zone lymphoma (1915 cases) was also elevated at 10+ years after transfusion (OR, 1.80).
  
  
  CONCLUSIONS
  Consistent with prior studies, blood transfusions did not increase risk of most HM subtypes. Patterns of elevated risk for lymphoplasmacytic and marginal zone lymphomas suggest an etiologic role for transfusion.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland 20892, USA. changcm@mail.nih.gov
authors.forename: Cindy M
authors.initials: CM
authors.lastname: Chang
authors.forename: Scott C
authors.initials: SC
authors.lastname: Quinlan
authors.forename: Joan L
authors.initials: JL
authors.lastname: Warren
authors.forename: Eric A
authors.initials: EA
authors.lastname: Engels
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019337:Hematologic Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D008297:Male; D065227:Transfusion Reaction