A new study suggests that common viral infections may play a larger role in cancer than has been previously thought. The nearly 29,000-participant population-based cohort study, conducted in Australia, found a significantly increased risk of 25 different cancers following kidney transplantation, including a more than threefold risk for 18 of those cancer sites.

The study authors argued that the immune system suppression required to carry out a kidney transplant was behind this increased risk, demonstrating a broader role of "common viral infections in the etiology of cancer."

Published in the December 19 Journal of the American Medical Association, the study included participants with end-stage kidney disease (ESKD) enrolled in an Australian dialysis and transplant registry between 1982 and 2003. They evaluated cancer incidence during three periods: the 5 years before participants started to receive therapy related to eventually undergoing a kidney transplant, the time from dialysis initiation to a first transplant, and from the date of the first transplant forward.

In addition to the increased risk following transplantation, a significant increase in the incidence of nine cancers also was seen during dialysis, with a greater than twofold increase for seven of them.

Analyzing the three separate time periods, the authors argued, "demonstrates that preexisting personal cancer risk factors, and factors related to primary renal disease, ESKD, or dialysis can be excluded as major contributors to the posttransplantation excess risk."