Dialysis and transplant patients face nearly three times the risk of dying from cancer as compared with the general population, according to new research.

Previous research has shown that patients on dialysis or have received a kidney transplant are at higher risk of developing cancer, but there have been few studies to assess cancer mortality rates among these patients.

To investigate, Eric H. Au, M.B.B.S., of the University of Sydney and colleagues compared the cancer-related mortality rates in kidney transplant recipients and dialysis patients with those of the general population. They published their results online in American Society of Nephrology on Feb. 14.

The researchers compared cancer mortality rates among transplant and dialysis patients using data collected from the Australia and New Zealand Dialysis and Transplant Registry from 1980 through 2014. They followed 52,936 dialysis patients for 170,055 patient-years, and tracked 16,820 transplant patients for 128,352 patient-years. The research team identified 2,739 cancer-related deaths among dialysis patients and 923 cancer deaths among transplant patients.

The Findings: Cancer Mortality Rates Higher in Dialysis and Transplant Patients

Over the span of 10 years, mortality rates were 6.1 percent in dialysis patients and 4.5 percent in transplant patients. Both dialysis and transplant recipients experienced over 2.5 times higher risks of cancer deaths than do individuals of the same age and gender in the general population, with the overall cancer standardized mortality ratios (SMRs) showing a 2.6 times higher risk for those on dialysis and 2.7 times higher risk for recipients of kidney transplants.

Multiple myeloma scored the highest SMR at 30.7 for dialysis patients, followed by testicular cancer at 17.0 and kidney cancer at 12.5. The highest SMRs for transplant recipients were non-Hodgkin lymphoma at 10.7, followed by kidney cancers at 7.8, and melanoma at 5.8.

Compared with the general population, women and younger patients experienced particularly high risks. Transplant and dialysis patients aged 20 to 34 had a tenfold higher risk of cancer-related death as compared with the general public.

The main driver for cancer deaths differed between the dialysis and transplant patients: the main driver for cancer deaths in dialysis patients was from cancers present before the start of dialysis, whereas the main driver for cancer mortality among transplant patients were cancers that developed after transplantation.

Of those who died from cancer-related causes, 9.6 percent of transplant recipients and 61.0 percent of dialysis patients had pre-existing cancer. SMR was 1.2 and 2.6 for dialysis and transplant patients, respectively, for de novo cancer. The increase in cancer-related deaths among kidney transplant recipients may be associated with the long-term immunosuppressive drugs patients must take after receiving an organ transplant.

Transplant patients died within a median of 8.6 years, while dialysis patients died within a median of two years. The research group observed that the higher cancer mortality rate in dialysis patients with pre-existing cancer that can lead to the development of end-stage renal disease (ESRD) and the relatively short time to cancer death would "suggest that despite commencement of dialysis, these patients' overall prognosis may still be predominantly affected by their underlying malignancy."

"Results from this study will assist clinicians and researchers in understanding the patterns of cancer-related mortality in dialysis and transplant patients," said Dr. Au in a press release. "Further research may help us understand which patients are particularly at risk of cancer and the reasons why they have higher chances of dying from cancer."