title: Cancer incidence in blood transfusion recipients.
abstract: BACKGROUND
  Blood transfusions may influence the recipients' cancer risks both through transmission of biologic agents and by modulation of the immune system. However, cancer occurrence in transfusion recipients remains poorly characterized.
  
  
  METHODS
  We used computerized files from Scandinavian blood banks to identify a cohort of 888,843 cancer-free recipients transfused after 1968. The recipients were followed from first registered transfusion until the date of death, emigration, cancer diagnosis, or December 31, 2002, whichever came first. Relative risks were expressed as ratios of the observed to the expected numbers of cancers, that is, standardized incidence ratios (SIRs), using incidence rates for the general Danish and Swedish populations as a reference. All statistical tests were two-sided.
  
  
  RESULTS
  During 5,652,918 person-years of follow-up, 80,990 cancers occurred in the transfusion recipients, corresponding to a SIR of 1.45 (95% confidence interval [CI] = 1.44 to 1.46). The SIR for cancer overall decreased from 5.36 (95% CI = 5.29 to 5.43) during the first 6 months after transfusion to 1.10 or less for follow-up periods more than 2 years after the transfusion. However, the standardized incidence ratios for cancers of the tongue, mouth, pharynx, esophagus, liver, and respiratory and urinary tracts and for squamous cell skin carcinoma remained elevated beyond 10 years after the transfusion.
  
  
  CONCLUSIONS
  The marked increase in cancer risk shortly after a blood transfusion may reflect the presence of undiagnosed occult cancers with symptoms that necessitated the blood transfusion. The continued increased risk of tobacco- and alcohol-related cancers suggests that lifestyle and other risk factors related to conditions prompting transfusion rather than transfusion-related exposures per se are important to the observed cancer occurrence in the recipients.
authors: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen South, Denmark. hhj@ssi.dk
authors: Henrik
authors: H
authors: Hjalgrim
authors: Gustaf
authors: G
authors: Edgren
authors: Klaus
authors: K
authors: Rostgaard
authors: Marie
authors: M
authors: Reilly
authors: Trung Nam
authors: TN
authors: Tran
authors: Kjell Einar
authors: KE
authors: Titlestad
authors: Agneta
authors: A
authors: Shanwell
authors: Casper
authors: C
authors: Jersild
authors: Johanna
authors: J
authors: Adami
authors: Agneta
authors: A
authors: Wikman
authors: Gloria
authors: G
authors: Gridley
authors: Louise
authors: L
authors: Wideroff
authors: Olof
authors: O
authors: Nyrén
authors: Mads
authors: M
authors: Melbye
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001771:Blood Banks; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008019:Life Style; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology; D018570:Risk Assessment; D012307:Risk Factors; D012537:Scandinavian and Nordic Countries; D013548:Sweden / Q000453:epidemiology; D065227:Transfusion Reaction