It is well known that chronic kidney disease (CKD) is linked to a higher cardiovascular mortality and increased risk of malignancy. What is unclear is whether reduced kidney function also leads to higher death from cancer. In a recent article published in AJKD, Dr. Germaine Wong and colleagues explore the link between reduced kidney function and cancer mortality. Dr. Wong (GW), lead author of the article, discussed the findings of the study with Dr. Abdo Asmar (eAJKD), eAJKD Contributor.
eAJKD: Please summarize your findings of increased cancer death with decreasing eGFR?
GW: Our study found that reduced kidney function is a poor prognostic factor for cancer mortality irrespective of the overall risk of cancer. The relationship between reduced GFR and cancer mortality is also linear, independent of the traditional risk factors for cancer mortality. Specifically, people with breast and urinary tract cancers with reduced kidney function are also more likely to die from these two cancers compared to those with eGFR equal to or greater than 60 ml/min.
eAJKD: How is this study different from other studies that evaluated CKD and cancer mortality?
GW: Our study is unique because it is a population-based cohort study that has the longest follow-up time (9.6 years) cancer mortality. A previous study conducted in Taiwan had shown a significant association between urinary tract and liver cancer mortality and moderate CKD. Our study is the first to show that reduced kidney function is a poor prognostic indicator for breast cancer, too.
eAJKD: In your study, you found that the association between reduced kidney function and cancer mortality appears to be organ specific. Can you please discuss this finding and the possible rationale behind it?
GW: A significant association was observed between reduced kidney function and the risk of urinary and breast cancer. As discussed previously, the increased risk of death from urinary tract cancers may be attributed to more disease recurrence, greater aggressiveness, and increased resistance to treatment. However, the rationale behind the increased risk of death from breast cancer is largely unclear. It may be attributed to potential under-treatment for the fear of toxic side effects. Women with breast cancer and chronic kidney disease may also be at risk of more aggressive disease due to the inherent inflammatory state associated with reduced kidney function.
eAJKD: How does the increased risk of cancer death in patients with mild to moderate kidney disease differ from those with end stage renal disease?
GW: Under the influence of immunosuppression in kidney transplant recipients, we have previously shown a 5-fold increased risk of dying from cancer compared to those without kidney transplants. For those on dialysis, the magnitude of the effect is certainly not as large, but people on dialysis with cancer do poorly compared to those not on dialysis. Among those with mild to moderate kidney disease, the risk of cancer death is increased but certainly not to the extent seen in dialysis and transplant patients.
eAJKD: How should clinicians use this result in their daily practice?
GW: This study raises the issues of early detection of cancer in patients with CKD. The implications of screening in patients with mild to moderate CKD is important and worth exploring in future studies.