Chronic kidney disease linked to increased colorectal cancer risk

Patients with chronic kidney disease (CKD) may be at increased risk for colorectal cancer (CRC)—regardless of transplant status—according to researchers in a recently published article in the Journal of Clinical Gastroenterology.

“A number of observational studies have shown a higher risk of cancer of various organs, including the colon, among patients with kidney diseases and kidney transplant,” wrote the authors, led by Yuga Komaki, MD, Department of Medicine, Section of Gastroenterology, Hepatology and Nutrition, The University of Chicago Medicine, Chicago, IL. “However, it remains largely unknown whether patients with CKDs are at increased risk for CRC.”

In recent years, surgeons have been performing an increasing number of renal transplants for the treatment of end-stage kidney disease, with marked improvement in the short- and medium-term clinical outcomes. Nevertheless, transplant and exposure to immunosuppressive drugs increases the risk of post-transplant cancer. The risk of CRC in these patients, however, is not fully understood. Therefore, Dr. Komaki and coauthors aimed to determine this risk, especially since this cancer can be prevented if caught early.

To that end, the authors performed a systematic review and meta-analysis focused on the risk of CRC in patients with CKD, and evaluated whether this association changes with kidney transplant. The team assessed 54 cohort studies evaluating the risk of CRC in patients with CKD, representing 1,208,767 patients. They included 17 retrospective cohort studies that reported incidence ratios or standardized incidence ratios (SIRs).

The primary outcome in the study was the SIR for CRC in patients with different types of CKD. The investigators performed separate analyses for pre- and post-transplant patients. They employed random-effects meta-analysis to determine the risk of CRC.

In three studies including patients with CKD who did not receive kidney transplant, investigators found a higher risk of CRC (pooled SIR: 1.18; 95% CI: 1.01-1.37; P=0.033). In the 15 studies that involved post-kidney transplant patients, the researchers found that pooled SIR was even higher at 1.40 (95% CI: 1.15-1.71; P=0.00080). Notably, the investigators found high heterogeneity in both samples, which they acknowledged was a limitation of the study.

“Our study demonstrated that patients with CKDs had a significant increased risk of CRC even before kidney transplantation took place,” Dr. Komaki and coauthors concluded.

The researchers suggested that chronic inflammation that accompanies CKD could lead to a variety of cancer types by inducing mutations, promoting resistance to apoptosis, and stimulating angiogenesis. Additionally, other researchers have found in rat models that advanced CKD could result in damage to the intestinal mucosal barrier that may result in malignant transformation.

“This comprehensive systematic review and meta-analysis showed that CKDs were associated with increased risk of CRC,” the authors concluded. “Our results indicated that patients were at risk regardless of whether they underwent transplant or not. Further studies are needed, but strict surveillance for CRC is indicated in this patient population.”