Blood transfusions and risk of non-Hodgkin's lymphoma subtypes and chronic lymphocytic leukemia.

UNLABELLED Allogeneic blood transfusion has been suggested as a risk factor for non-Hodgkin's lymphoma (NHL), possibly specific to certain NHL subtypes, or chronic lymphocytic leukemia (CLL). Self-reported transfusion history and risk of NHL subtypes and CLL were examined in a cohort of 37,934 older Iowa women, using data from a questionnaire mailed in 1986. Through 1997, 229 cases of NHL and 57 cases of CLL in the cohort were identified through linkage to the Iowa Surveillance, Epidemiology and End Results Cancer REGISTRY Women who reported ever receiving a blood transfusion were at increased risk for all NHLs [age adjusted relative risk (RR), 1.6; 95% confidence interval (CI), 1.2-2.1). On the basis of the Working Formulation classification, blood transfusion was positively associated with low-grade NHL (RR, 2.7; 95% CI, 1.7-4.5) but not with intermediate-grade NHL (RR, 1.1; 95% CI, 0.7-1.6); there were only 8 cases of high-grade NHL. Blood transfusion was positively associated with follicular (RR, 2.8; 95% CI, 1.6-5.1) and small lymphocytic (RR, 3.4; 95% CI, 1.5-7.9) NHL subtypes but not with diffuse NHL (RR, 1.0; 95% CI, 0.7-1.5). There was also a positive association with CLL (RR, 1.7; 95% CI, 1.0-3.0). Finally, transfusion was associated with nodal (RR, 1.8; 95% CI, 1.3-2.5) but not extranodal (RR, 1.2; 95% CI, 0.7-2.1) NHL. Further adjustment for marital status, farm residence, diabetes, alcohol use, smoking, and red meat and fruit consumption did not alter these associations. In conclusion, prior blood transfusion was associated with NHL and CLL, and the strongest associations were seen for low-grade NHL, particularly follicular and small lymphocytic NHL.