Cancer incidence in blood transfusion recipients.
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.
Hjalgrim
Henrik
H
Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen South, Denmark. hhj@ssi.dk
Edgren
Gustaf
G
Rostgaard
Klaus
K
Reilly
Marie
M
Tran
Trung Nam
TN
Titlestad
Kjell Einar
KE
Shanwell
Agneta
A
Jersild
Casper
C
Adami
Johanna
J
Wikman
Agneta
A
Gridley
Gloria
G
Wideroff
Louise
L
Nyrén
Olof
O
Melbye
Mads
M
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