CKD and the risk of incident cancer.

Previous studies report a higher risk of cancer in patients with ESRD, but the impact of less severe CKD on risk of cancer is uncertain. Our objective was to evaluate the association between level of kidney function and subsequent cancer risk. We performed a retrospective cohort study of 1,190,538 adults who were receiving care within a health care delivery system, had a measurement of kidney function obtained between 2000 and 2008, and had no prior cancer. We examined the association between level of eGFR and the risk of incident cancer; the primary outcome was renal cancer, and secondary outcomes were any cancer and specific cancers (urothelial, prostate, breast, lung, and colorectal). During 6,000,420 person-years of follow-up, we identified 76,809 incident cancers in 72,875 subjects. After adjustment for time-updated confounders, lower eGFR (in milliliters per minute per 1.73 m(2)) was associated with an increased risk of renal cancer (adjusted hazard ratio [HR], 1.39; 95% confidence interval [95% CI], 1.22 to 1.58 for eGFR=45-59; HR, 1.81; 95% CI, 1.51 to 2.17 for eGFR=30-44; HR, 2.28; 95% CI, 1.78 to 2.92 for eGFR<30). We also observed an increased risk of urothelial cancer at eGFR<30 but no significant associations between eGFR and prostate, breast, lung, colorectal, or any cancer overall. In conclusion, reduced eGFR is associated with an independently higher risk of renal and urothelial cancer but not other cancer types.