Smoking is a risk factor inferring a minor increase in risk.
The best established risk factor is obesity. It is usually sporadic and unilateral but can also occur in hereditary forms characterized by an earlier age of onset, multiple primary, bilateral tumors. The best established prognostic factor for RCC is stage. Other factors like cell type, age at diagnosis, and tumor size, have been implicated to affect survival. Tumor and normal kidney tissues were examined from sporadic, non-hereditary RCC cases.