Threefold higher malignancy incidence found.
Renal transplant recipients are at markedly increased risk of cancer at numerous anatomical sites, according to an Australian study.
The renal transplant population has more than three times the number of cancers as would be expected in the general population, according to their report in the Journal of the American Medical Association (2006;296:23:2823-2831).
The researchers examined data on 28,855 patients with end-stage renal disease (ESRD), who had 273,407 person-years of follow-up. Led by Claire M. Vajdic, PhD, of the University of New South Wales in Sydney, the investigators calculated the standardized incidence ratio (SIR) for all cancers except nonmelanoma skin cancer and malignancies known to be a frequent cause of ESRD.
A cancer SIR is a ratio of observed to expected numbers of cancers in the general population. The observed number of cancers in the renal transplant group was 1,236; the expected number was 378. This works out to a SIR of 3.27 (1,236 divided by 378).
Slight rise in incidence during dialysis
Cancer incidence rose only slightly during dialysis and prior to renal replacement therapy (RRT). Up to five years before RRT, 689 incidence cancers were observed whereas 594 were expected, for an SIR of 1.16. For patients on dialysis, 870 cancers were observed and 643 were expected (SIR, 1.35). The overall cancer risk for men and women was similar five years prior to RRT, but higher in wom-en than men during dialysis and higher in men than in women after transplantation.
“After kidney transplantation,” the authors concluded, “a wide variety of cancers across a number of organ systems occur with substantially increased incidence. Most, but not all, of these cancers are those with known or suspected viral causes. In contrast, cancer incidence was only slightly increased before kidney transplantation. Our findings point to an important role of the interaction between common viral infections and the immune system in the etiology of cancers at a broad range of sites.”
Insight into viral etiologies
Following transplantation, the researchers observed significant excesses of cancers of the lip,
mouth, salivary glands, tongue, stomach, esophagus, colon, anus, liver, gall bladder, lung, and Kaposi sarcoma, among others. A viral etiology has been suggested or established for cancers of the liver, cervix, tongue, mouth, and tonsil, as well as Kaposi sarcoma, Hodgkin disease, and certain types of non-Hodgkin lymphoma. In addition, of the 18 specific cancers with a greater than threefold increase in risk, five were at sites known to be caused by human papillomavirus (mouth, tongue, vulva, vagina, and penis), the study found.
Previous population-based estimates of cancer risk after renal transplantation, which have included nonmelanoma skin cancer and cancers that frequently cause ESRD, have found a three- to fourfold increased risk. “Our study confirms and extends this finding, being the first to our knowledge with sufficient power to examine site-specific cancer risk for a wide spectrum of cancers,” the authors wrote.
Data for the study came from the Australia and New Zealand Dialysis and Transplant Registry, established in 1971, and Australia’s National Cancer Statistics Clearing House, which is a compilation of data from all eight population-based state and territory registries to which all cases of primary invasive cancer (except nonmelanoma skin cancer) must be reported.