Kidney Cancer

Cancer occurs when cells in the body change (mutate). These changes allow them to start growing out of control. These cells can form lumps of tissue called tumors. They can spread to other parts of the body. Cancer that starts in the cells that make up the kidney is called kidney or renal cancer.

Understanding the kidneys

The kidneys are 2 bean-shaped organs about the size of a fist. They’re found in the low back. There’s one kidney on each side of the spine. The kidneys help keep the body alive by filtering waste and extra fluid out of the blood. The kidneys send this liquid and waste (urine) to the bladder through tubes called the ureters. Urine then leaves the body through another tube called the urethra.

When kidney cancer forms

Kidney cancer starts when cells that make up the kidney change. These cells don’t work the way they should and they grow out of control. Over time, this cancer can change the way the kidney works. Kidney cancer often starts in one kidney. But sometimes it’s in both kidneys.

Kidney cancer may spread beyond the kidney to other parts of the body. This spread is called metastasis. The more cancer spreads, the harder it is to treat.

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