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People with kidney disease are often diagnosed with late-stage cancers. Mihailo Milovanovic/Getty Images
  • Researchers say people with kidney disease have a higher risk of cancer as well as a higher risk of dying from the disease.
  • They say many people with kidney disease are diagnosed with late-stage cancers because doctors are more focused on cardiovascular health issues for these patients.
  • They also note that some cancer treatments are not viable for people with kidney disease due to the damage the treatments can do to kidneys.

The connection between kidney disease and cancer has been discussed by experts in various settings and studies, but it isn’t widely known by the general public, experts say.

A new study may have the most dramatic evidence yet of this link.

In their study, researchers conclude that people with kidney disease may have an increased risk of cancer and may be more likely to die from cancer.

The study, published in the American Journal of Kidney Diseases, used healthcare databases in Ontario, Canada, to categorize people according to their kidney function.

The researchers looked at 14 million residents who receive single-payer publicly funded healthcare under the Ontario Health Insurance Plan.

Scientists used blood test data or records that identify patients receiving dialysis or patients with kidney transplants. The study then looked at their risk of being diagnosed with cancer and of dying of cancer.

Here’s what researchers found:

  • People with mild-to-moderate kidney disease as well as kidney transplant recipients had a higher risk of cancer than people with normal kidney function.
  • People with kidney disease had a higher risk of dying from cancer than people with normal kidney function, particularly from cancers such as bladder, kidney, and multiple myeloma.
  • In the study, 10 to 15 percent of kidney disease patients later developed cancer.

Chronic kidney disease and cancer are already connected in a number of ways.

Chronic kidney disease is already a known risk factor for cancer. Conversely, cancer can cause chronic kidney disease either directly or indirectly through the adverse effects of therapies.

Dr. Abhijat Kitchlu, a nephrologist in the Division of Nephrology in the Department of Medicine at the University of Toronto, was the lead physician in the study.

Kitchlu told Healthline that the findings show that improved strategies among physicians to detect and treat cancer in people with kidney disease are needed.

“Patients with kidney disease typically have an underlying degree of inflammation and have reduced immune system function,” he said. “Their immune systems may be impaired, and cancers in kidney patients, especially those that are related to the immune system, can go undetected.”

He noted that since kidney patients also have cardiovascular risk factors, most of the attention from doctors beyond the kidney disease itself is on preventing bad cardiovascular outcomes.

“For that reason, routine cancer screening can get pushed to the back burner, and that can lead to some delayed detection,” he said.

Kitchlu noted that due to these delays people with kidney disease typically have more advanced cancers at the time of diagnosis.

“We saw more stage four cancers in this study potentially because of less cancer screening and more attention to the cardiovascular issues,” he said.

Another issue that the study explored is that many treatments for cancer can harm kidneys, so kidney patients who also have cancer can find it difficult to find a viable cancer treatment.

“Kidney patients are often not allowed in clinical trials for cancer, either, because the drugs have restrictions on eligibility depending on kidney function,” Kitchlu said.

“Even mildly reduced kidney function patients are excluded. There are often very few options for patients.”

The study authors noted that while cardiovascular disease has traditionally been viewed as the predominant cause of death in people with chronic kidney disease, “the proportion of cancer-related death may be under-appreciated in this population, particularly in those with mild-moderate kidney dysfunction.”

“It is important for every kidney clinician to think about cancer risk as well, and individualized cancer screening should be done,” Kitchlu added. “We believe physicians need to bear that in mind.”

Among the next steps for physicians, Kitchlu suggests, is finding ways to include more people with kidney disease in cancer clinical trials.

The best way to do that is to detect cancer earlier with less invasive testing, including potentially using liquid biopsies, which are blood tests that can identify biomarkers in the blood that can detect the presence of cancer in early stages.

“There’s a lot of interest in liquid biopsies and other methods of early detection, which could be an ideal way to check for cancer in kidney disease patients because it is far less invasive,” Kitchlu said.

“We could simplify screening for kidney disease patients with a less invasive method of detection,” he added.