Decreased kidney function may place individuals at increased risk of cancer-related death, new study findings suggest.

In a study that included 4,077 individuals aged 49-97 years, each 10 mL/min/1.73 m2 decrease in estimated glomerular filtration rate (eGFR) was associated with a significant 18% increase in cancer-specific mortality, independent of age, smoking status, gender, blood pressure, and serum fibrinogen, and fasting blood glucose levels, according to findings published online ahead of print in the American Journal of Kidney Diseases.

The highest risks of cancer death associated with reduced kidney function were in subjects with urinary tract and breast cancers, Germaine Wong, MD, PhD, of Westmead Hospital in New South Wales, Australia, and colleagues reported. Compared with subjects with an eGFR of 60 or higher, those with an eGFR below 60 had a 2.5 times increased risk of death from urinary tract cancers after adjusting for age, gender, and smoking status. Women with an eGFR below 60 had a twofold increased risk of death from breast cancer, after adjusting for age, smoking, and employment status.

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Additionally, among subjects diagnosed with incident cancer after the start of the study, the overall risk of cancer death increased significantly by at least 14% for each 10 mL/min/1.73 m2 decrease in eGFR, in adjusted analyses. In this group of cancer patients, participants with an eGFR below 45 had a 2.3-fold increased risk of cancer death than those with an eGFR of 75 or higher.

“Our observed link between reduced kidney function and cancer mortality is novel,” the authors wrote. “Although there are emerging data showing an increased risk of non-cardiovascular death in the non-dialysis-dependent population, the linear association between decreased kidney function and cancer-specific mortality reported in our study is a new finding.”

Dr. Wong’s group observed that epidemiologic studies suggest that cancers of the urinary tract may be more resistant to treatment and prone to recurrence among individuals with decreased renal function.

The investigators noted that breast cancer is one of the few cancers that do not incur a heightened risk in patients with kidney disease and with kidney transplants. “The observed increased risk of death from breast cancer in women with reduced eGFR therefore is unexpected and strengthens our hypothesis that having decreased kidney function itself is a predictor for poor cancer outcomes,” they wrote.

During a median follow-up period of 12.8 years, 1,418 deaths occurred. Of these, 370 were due to cancer.