Cancer as a late-onset complication of kidney transplantation.

A Scandinavian material of 2,683 transplanted patients, 59 of whom were diagnosed to have tumours, was analysed and the following found: 1) a greatly increased incidence of mesenchymal tumours (especially reticulosarcomata), 2) a greatly increased occurrence of "chronic pyelonephritis" (as a primary disease) among tumour patients, and 3) a correlation between tumour incidence and HLA-B mismatch between donor and recipient. Based on this material it is proposed that chronic immunostimulation in the recipient caused by graft antigens and bacteria and virus antigens puts a stop to T-suppressor lymphocyte function and subsequent proliferation of the lymphoid tissue, and that this is a major factor in the appearance of tumours derived from mesenchymal tissue, whereas the occurrence of ectodermal tumours is a result of a series of other oncogenetic factors.