CANCER MORBIDITY IN BLOOD RECIPIENTS - RESULTS OF A COHORT STUDY

Blood transfusions involve the transfer of relatively large volumes of body fluids and cellular material between individuals. A variety of p athogens like viruses, some of which are associated with development o f certain tumours, are known to be transmitted by this route. Blood re cipients were identified during 1981-1982 in the register of the hospi tal blood centre, and in-patients by the in-patient and discharge regi ster of the hospital. Tumour occurrence and vital status were determin ed by means of the population-based regional tumour register. Age, gen der and calendar-year specific rates from the general population were used to calculate expected values. In a cohort study of 3177 blood rec ipients, increased numbers of malignant lymphomas [13 vs. 4.8 expected , standard morbidity ratio (SMR) 2.70, 95% confidence interval (CI) 1. 44-4.62] and skin cancers [12 vs. 5.2 expected, SMR 2.29,95% CI 1.19-4 .01] were seen 3 to 9 years after transfusion. In a second cohort stud y of 29910 hospitalised patients, a total of 37 (29.8 expected) malign ant lymphomas was found in 28 338 patients with no transfusion and 10 (2.73 expected) in 1572 patients with a transfusion, 3 to 9 years afte r the hospitalisation. The incidence rate ratio between these groups w as 3.11 (95% CI 1.56-6.20) using a Mantel-Haenszel estimator with age stratification. Non-melanomatous skin cancers had an incidence ratio o f 2.74 (95% CI 1.25-6.00). We conclude that, in the cohorts discussed here, malignant lymphomas and skin cancer occur more often in blood re cipients than in controls. It remains to be established whether this i s due to factors covariating with transfusion or by the transfusion it self. Further studies on these putative associations are warranted, as are analytical studies of the epidemiology of malignant lymphomas, es pecially non-Hodgkin's lymphoma, whose aetiology is still poorly under stood.