What is kidney cancer?
Kidney cancer is a cancer that starts in the kidneys. To understand kidney cancer, it helps to know about the normal kidneys and what they do.
About the kidneys
The kidneys are a pair of bean-shaped organs, each about the size of a fist. They are shown in the picture below. One is on either side of the spine. The lower ribcage protects the kidneys.
Small glands called adrenal glands sit above each of the kidneys.
The kidneys’ main job is to filter your blood and help the body get rid of excess water, salt, and waste products. The waste is made into urine. Urine leaves the kidneys through long, thin tubes called ureters, which connect to the bladder. The urine is stored there until you urinate (pee). The kidneys also make hormones that help control blood pressure and tell the body to make more red blood cells.
We have 2 kidneys, but a person can live with less than even one complete kidney. Some people live without any working kidneys at all. Their blood is filtered by a machine in a process called dialysis.
Renal cell carcinoma
The most common type of kidney cancer is called renal cell cancer (also known as renal cell carcinoma or RCC).
Like other cancers, RCC begins small and grows larger over time. It usually grows as a single mass or tumor within the kidney. But a kidney can have more than one tumor. Sometimes tumors are found in both kidneys at the same time.
There are many subtypes of RCC, based mainly on how the cancer cells look under a microscope. Knowing the RCC subtype can affect treatment and can also help your doctor figure out if your cancer might be due to an inherited genetic syndrome.
- Clear cell RCC (the most common type)
- Papillary RCC (the second most common subtype)
- Chromophobe RCC
- Collecting duct RCC
- Other rare types of RCC
Other types of kidney cancer
Transitional cell carcinoma: About 5% to 10% of cancers in the kidney are transitional cell carcinomas (TCCs), also known as urothelial carcinomas. TCCs don’t start in the kidney itself but rather in the lining of the renal pelvis (where the urine goes before it enters the ureter). This lining is made up of cells called transitional cells that look like the cells that line the ureters and bladder.
To find out more about transitional cell carcinoma, see our document Bladder Cancer.
Wilms tumor: This type of cancer is almost always found in children and is very rare in adults. To learn more, see our document Wilms Tumor.
Renal sarcoma: Renal sarcoma is a rare type of kidney cancer that starts in the kidney’s connective tissue or blood vessels. Sarcomas are discussed in more detail in our document Sarcoma-Adult Soft Tissue Cancer.
Benign (non-cancerous) kidney tumors
Some kidney tumors are benign (not cancer). They don’t spread to other parts of the body, although they can still grow and cause problems.
- Renal adenoma (the most common type of benign kidney tumor)
The rest of this document is about renal cell carcinoma and not other types of kidney tumors.
Last Medical Review: 04/29/2014
Last Revised: 01/13/2015