The main functions of the kidneys include filtering the blood and maintaining fluid levels. Kidney cancer, also referred to as renal cancer, occurs when cells of the kidneys become cancerous. Often this cancer first appears in the lining of the tiny tubules of the kidneys. Luckily, most forms of kidney cancer are found before they spread. Although the exact cause of kidney cancer is unknown, there are several risk factors including, but not limited to, the following: smoking, long-term use of pain medications, kidney disease, certain genetic conditions, having lymphoma, and high blood pressure. It is essential for anyone with these conditions to eat in a way that is supportive of the kidneys.