Baseline renal function and the risk of cancer among apparently healthy middle-aged adults.

Background: The association between mildly impaired renal function with all-site and site-specific cancer risk is not established. We aim to explore this association among apparently healthy adults.

Methods: We followed 25,073 men and women, aged 40-79 years, free of cancer or cardiovascular disease at baseline who were screened annually in preventive healthcare settings. The estimated glomerular filtration rate (eGFR) was calculated using the CKD Epidemiology Collaboration equation (CKD-EPI) and classified into four mutually exclusive groups: <60, 60-74, 75-89, ≥90 (mL/min/1.73 m²). The primary outcome was all-site cancer while the secondary outcome was site-specific cancer. Cancer data was available from a national registry.

Results: Mean age at baseline was 50 ± 8 years and 7973 (32 %) were women. During a median follow-up of 9 years (IQR 3-16) and 256,279 person years, 2045 (8.2 %) participants were diagnosed with cancer. Multivariable Cox model showed a 1.2 (95 %CI: 1.0-1.4 p = 0.05), 1.2 (95 %CI: 1.0-1.4 p = 0.02), and 1.4 (95 %CI: 1.1-1.7 p = 0.003) higher risk for cancer with eGFR of 75-89, 60-74, and < 60, respectively. Site-specific analysis demonstrated a 1.8 (95 %CI: 1.2-2.6 p = 0.004), 1.7 (95 %CI: 1.2-2.6 p = 0.004) and 2.2 (95 %CI: 1.3-3.6 p = 0.002) increased risk for prostate cancer with eGFR of 75-89, 60-74, and < 60, respectively. eGFR< 60 was associated with a 2.0 (95 %CI: 1.1-3.7 p = 0.03) and 3.7 (95 %CI: 1.1-13.1 p = 0.04) greater risk for melanoma and gynecological caner respectively.

Conclusions: CKD stage 2 and worse is independently associated with higher risk for cancer incidence, primarily prostate cancer. Early intervention and screening are warranted among these individuals in order to reduce cancer burden.