Using a more sensitive test than is commonly used in the NHS, researchers have been able to show, for the first time, that even mild kidney disease is associated with an increased risk of developing and dying from cancer.

The new research, led by the University of Glasgow and published today in the journal EClinicalMedicine, shows that the more sensitive ‘cystatin C’ test was able to identify a heightened risk of developing and dying from cancer in people with chronic kidney disease.

Using data from the UK Biobank alongside the simple blood test, researchers were able to demonstrate that mild kidney disease is associated with a 4% increased risk of developing cancer and a 15% increased risk of dying from cancer. In people with more advanced kidney disease, researchers found a 19% increased risk in developing cancer and a 48% increased risk in dying from cancer.

This heightened risk of developing and dying from cancer was not identified when kidney function is estimated using serum creatinine – the test most commonly used in healthcare settings – to estimate a patient’s kidney function.

Chronic kidney disease, characterised by gradual loss of kidney function over time, is common, affecting around 10% of the population. Cancer is already known to be more common in people with kidney failure, especially in people requiring dialysis or a kidney transplant. Although kidney failure is relatively uncommon, mild kidney disease may be present in one third of the population, although it is usually asymptomatic, not routinely diagnosed and therefore monitored infrequently.

Chronic kidney disease is also associated with premature cardiovascular disease and mortality. Using cystatin C testing researchers are already able to show that mild kidney disease is associated with 20-30% increase in risk of cardiovascular disease and early death, and this heightened risk is more pronounced in people with more advanced kidney disease.

Dr Jennifer Lees said: “Our results show that mild kidney disease is clinically important in predicting cancer risk, as well as the risk of cardiovascular disease and early death. However, identifying this excess risk requires measurement of more sensitive markers of kidney dysfunction such as cystatin C. We were not able to see the same risk when using the less sensitive, but more routinely used serum creatinine test.”

Chronic kidney disease is not currently considered in cancer risk prediction tools used by GPs to guide referrals for investigation of potential cancer symptoms. Researchers now believe that if chronic kidney disease was recognised as an important risk factor for cancer, it may be that milder symptoms in patients with this condition would trigger earlier referrals, prompting earlier treatment and better outcomes/survival.

Dr Lees said: “Our research suggests that greater uptake of cystatin C testing could be used to improve patient outcomes by identifying cancer risks earlier, thereby increasing patients’ quality of life and chance of survival.

“Although cystatin C testing is available in most developed countries, it is more expensive than creatinine testing in many laboratories. However, we believe more widespread use could drive down the costs of testing and aid further research into identifying and addressing the factors responsible for worse cancer outcomes in people with kidney disease.”

The study, ‘Kidney function and cancer risk: an analysis using creatinine and cystatin C in a cohort study’ is published in EClinicalMedicine. The work was funded by the Scottish Government Chief Scientist Office, ANID Becas Chile, the Medical Research Council, the British Medical Association and the British Heart Foundation.