High incidence of malignancy in polyomavirus-associated nephropathy in renal transplant recipients

Human polyomaviruses (PV), including JC and BK virus, have been reported to cause polyomavirus-associated nephropathy (PVAN), in renal transplant patients. PV infection has been demonstrated to be associated with malignancies in animals; however, the association between malignancy and viral infections in humans is not clear. We retrospectively reviewed our 864 (M:F=502:362) kidney transplant patients over the past 25 years. We identified PVAN in 6 patients (0.69%), including BK nephropathy (n=5) and JC nephropathy (n=1). Three patients (50%) improved after reducing the immunosuppression, but 3 (50%) progressed to graft loss despite this reduction. Malignancy occurred in 5 out of the 6 patients (83%; P<.0001 compared with patients without PVAN), including transitional cell carcinoma (n=2), renal cell carcinoma (n=1), squamous cell carcinoma of skin (n=1) and Kaposi sarcoma (n=1). We concluded that kidney transplant patients with PVAN are at a significantly greater risk to develop malignancy. Whether this is due to a direct effect of PV infection or the result of overimmunosuppression remains to be determined in a future study.