Umbrella review finds mostly low-certainty evidence on renal cancer risk factors

Researchers searched four databases through January 2026 and identified 44 systematic reviews or meta-analyses, including 32 for data extraction. The umbrella review assessed 84 summary effect estimates across lifestyle, circulating biomarker, and disease- or treatment-related factors. Review quality ranged from critically low to moderate, based on AMSTAR 2, and evidence certainty was assessed using GRADE and evidence-classification criteria.

Most associations were supported by very low-certainty evidence. Seven associations were rated as low certainty: moderate alcohol consumption, HCV infection, obesity, ever smoking, kidney transplantation, heart transplantation, and each additional daily serving of vegetables. The authors reported increased RCC risk associated with obesity, HCV infection, ever smoking and kidney or heart transplantation; greater vegetable intake was associated with lower risk. Moderate alcohol consumption was also associated with lower risk, but the authors said this finding needs validation in larger studies with longer follow-up.

The findings synthesize existing evidence but do not establish causal effects. The authors caution that the overall evidence is low to very low certainty and call for high-quality prospective studies. The review was funded by West China Hospital and China’s National Natural Science Foundation; the authors reported no competing interests.