Chronic antigenic stimulation from the graft as a possible oncogenic factor after renal transplant.

In the period 1956-1976, 3 649 kidney transplantations were performed on 3 040 patients in Scandinavia. In the same period 67 primary malignant tumours were detected in these patients. In comparisons using age and sex-specific incidence in a background population, the observed tumour incidence was significantly higher than expected. Analyses were made in regard to a number of factors with potential influence on oncogenesis. The interval from transplantation to appearance of tumour was significantly longer in the recipients of grafts from living relatives than in cadaver kidney recipients. Significant correlation of tumour incidence was found with HLA mismatch in recipients of necrokidneys. Chronic interstitial nephritis as underlying kidney disease and blood transfusion showed correlation with tumour incidence. From these observations the hypothesis is proposed that a chronic antigen effect is a dominant factor among the numerous possible oncogenic mechanisms in patients with transplants.