Risk of hematological malignancy in blood donors: A nationwide cohort study

BACKGROUND: There has been a concern that blood donations can increase the risk of hematological malignancies. We investigated if blood donations increase the risk of developing hematological malignancies, specifically acute lymphoblastic leukemia, acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia, Hodgkin lymphoma, and myeloma, as well other non‐Hodgkin lymphoma. STUDY DESIGN AND METHODS: In total, the study included 1,021,433 Swedish blood donors, with 19.5 million person‐years of follow‐up. Two sets of analysis were performed. In the first cohort analysis, standardized incidence ratios (SIRs) were calculated, comparing the incidence of the different types of hematological cancers in blood donors to that of the general population. In the second analysis, a nested case–control study was conducted, investigating the association between number of donations and the risk of each type of malignancy. RESULTS: Apart from a modestly elevated risk of CLL (SIR, 1.07; 95% confidence interval [CI], 1.01‐1.15) and a modestly decreased risk of AML (SIR, 0.85; 95% CI, 0.77‐0.83), the risk of hematological malignancies did not differ between blood donors and the general population. In the nested case–control study there were no convincing associations between number of prior whole blood donations and site‐specific malignancy risk. CONCLUSIONS: There was no convincing evidence of an increased risk in any hematological malignancy when interpreting the results from both series of analyses.