Long-Term Dialysis Boosts Cancer Risk After Renal Transplantation

BERLIN—Patients on long-term dialysis prior to receiving a donor kidney are at increased risk for cancer following transplantation, according to findings presented at the 24th International Congress of The Transplantation Society.

In a study of 5,417 patients, researchers led by Germaine Wong, MBBS, PhD, a nephrologist and Early Career Research Fellow at the University of Sydney's School of Public Health in Australia, found that patients on dialysis for more than 4.5 years had a greater than threefold increased risk for lung cancer compared with those who had dialyzed for fewer than 1.5 years. They also had a 2.5 times increased risk for urinary tract cancer.

Furthermore, patients on dialysis for 2.5 to 4.5 years had a 2.5 times increased risk for colorectal cancer compared with those on dialysis for fewer than 1.5 years.

“Increased duration on dialysis increases the risk of acquired cystic disease, which is a risk factor for renal cancer, but we cannot explain the increased risk for the other cancers,” Dr. Wong told Renal & Urology News.

Dr. Wong's team analyzed data from the Australian and New Zealand Dialysis and Transplantation Registry. They focused on patients who received a living- or deceased-donor kidney transplant from January 1997 to December 2009. The investigators excluded patients who had multiple organ grafts, pre-emptive transplants, had primary renal disease caused by cancers such as multiple myeloma and renal cancers, or a history of cancer prior to starting dialysis.

Cancer developed in 454 patients who met these criteria. The investigators compared them to another 5,963 patients in whom cancer did not develop. The two groups had different average ages, races, smoking status, and prevalence of peripheral vascular disease but a similar ratio of men to women (about 60% of each group were men).

Longer time on dialysis prior to transplantation was associated with a higher incidence of cancer. The adjusted risk for urinary tract cancer, lung cancer, and colorectal cancer each were higher with longer dialysis.

Overall, the adjusted probability of having any cancer by 12 years after transplantation was 15% among patients dialyzed for less than 1.5 years, 18% among those dialyzed 1.5-2.5 years, 21% for 2.5-4.5 years of dialysis, and 23% for more than 4.5 years of dialysis. The respective probabilities for urinary tract cancer at 12 years were 2.1%, 2.7%, 2%, and 5.1%.

The results fit with the researchers' initial hypothesis that immunosuppression is not the only risk factor for cancer after transplantation, but long-term uremia, for which dialysis is a surrogate indicator, is also.

To find a way to mitigate the effects of the increased risk for cancer, he and his colleagues are exploring the best options for early cancer diagnosis. One of their studies assessed early detection of renal cell carcinoma in renal transplant recipients using ultrasound (Nephrol Dial Transplant (2011;26:1729-1739). They are also conducting a large international trial of the effectiveness of immunologic fecal occult blood testing for colorectal cancer screening across all stages of chronic kidney disease (BMC Public Health 2011;11:516).

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