Cancer starts when the structure of the DNA (deoxyribonucleic acid) alters - a genetic mutation. DNA provides the cells with a basic set of instructions, much like a computer program for life. The instructions tell cells when to grow, reproduce, and die, among other things. When there is a genetic mutation cells grow in an uncontrollable manner, eventually producing a lump (tumor).

If the cancer is left untreated it grows and eventually spreads to other parts of the body, usually through the lymphatic system - a series of nodes (glands) that exist throughout the body. The lymph glands produce many of the cells of our immune system. As soon as the cancer reaches the lymphatic system it can spread anywhere in the body and invade bones, blood and organs. The cancer cells continue reproducing uncontrollably, gradually occupying more and more space.

Our kidneys are part of our urinary system which gets rid of waste and excess fluid and electrolytes from the blood. The kidneys also control the production of red blood cells and regulate your blood pressure.

There are over 1 million nephrons in each kidney. Nephrons are the tiny filtering units in the kidneys - they filter out waste products as well as minerals and water the body needs expel. The liquid waste is called urine. Urine flows through the ureters; two narrow tubes that connect the kidneys to the bladder. Urine is stored in the bladder. When we urinate (pee) urine travels down another tube, called the urethra, and out of the body.

Transitional cell carcinoma
Cancer develops in the tissue that forms the tubes that connect the kidneys to the bladder. This type of cancer can begin in the ureters and also in the bladder itself.

Wilms' tumor 
A childhood kidney cancer caused by the loss or inactivation of a tumor suppressor gene called QT1 on chromosome 11. Tumor suppressor genes generally suppress tumor growth and control cell growth.

Renal cell carcinoma
This type of cancer typically starts in the cells that line the tiny tubes in each nephron. Generally, renal cell tumors grow as one, single mass. However, it is possible for more than one tumor to grow in one kidney, and sometimes in both kidneys.