Understanding Kidney Cancer

The kidneys are a pair of bean-shaped organs that lie on either side of the spine, just above the waist. Their main function is to filter the blood and produce urine so that the body can eliminate its liquid waste. The kidneys also produce substances that are involved in regulating blood pressure and generating red blood cells. This section was put together to help you learn more about kidney cancer.

WHAT IS KIDNEY CANCER?

Kidney cancer is an abnormal, uncontrolled growth of cells in the kidney. According to the American Cancer Society, the most common type is renal cell cancer (also called renal cell carcinoma), which accounts for about 85 percent of all kidney tumors.

Renal cell cancer may develop in one or both kidneys. In the early stages, kidney cancer usually causes no obvious signs or symptoms. As kidney cancer grows, it may invade organs near the kidney such as the liver, colon or pancreas. Kidney cancer cells may also break away from the original tumor and spread (or metastasize) to other parts of the body such as the lymph nodes, bones or lungs, with about one third of cases showing metastasis at the time of diagnosis.

HOW MANY PEOPLE GET KIDNEY CANCER?

The American Cancer Society predicts that there will be more than 35,700 new cases of kidney cancer in the United States this year, with almost 12,500 people dying from the disease.

WHAT CAUSES KIDNEY CANCER?

The exact cause of renal cell cancer is not known. However, certain risk factors are known to be associated with it, including smoking, overuse of certain painkillers, long-term dialysis, exposure to asbestos or cadmium, being overweight and eating a diet high in fat. In addition, some genetic factors and diseases such as tuberous sclerosis may increase one’s risk. Renal cell carcinoma typically occurs in people over the age of 50 and is twice as likely to occur in men than in women.

HOW IS KIDNEY CANCER DIAGNOSED?

In most cases, renal cell cancer is found only after a person has some sort of symptom of a problem. Because there are no blood or urine tests to specifically screen for renal cell cancer, it is sometimes found by accident when a person is having tests for something else.

Blood in the urine is the most common sign of kidney cancer, although this may also be caused by a bladder infection or some other less serious condition. Signs and symptoms of renal cell carcinoma can include:

• Blood in the urine
• Low back pain that is not caused by an injury
• Mass or lump in the abdomen
• Tiredness/fatigue
• Rapid, unexplained weight loss
• Fever that is unrelated to a cold, the flu or other infection
• Swelling of ankles and legs
• High blood pressure

These symptoms can also be caused by noncancerous conditions—only your doctor can tell for sure. If there is any reason to suspect kidney cancer, the doctor will take your medical history, conduct a physical exam and may perform imaging tests such as CT scan, MRI or ultrasound to produce a detailed picture of the inside of the body. Laboratory tests such as urine and blood tests may also be performed to check for problems that may occur along with kidney cancer such as too few or too many red blood cells.

WHAT IS CANCER STAGING?

Staging is the process of finding out how far the cancer has spread (or metastasized). It is very important because, to a large extent, treatment and outlook for recovery depend on the stage of the cancer. In general, the lower the number, the less the cancer has spread.

If your cancer is…	It has…
Stage I	Not spread and is only in the kidney.
Stage II	Spread to the fatty tissue around the kidney but not to the capsule around the kidney.
Stage III	Spread to blood vessels or lymph nodes around the kidney.
Stage IV	Spread to nearby organs (like the bowel or pancreas) or to other places (like the lungs).

Source: American Joint Committee on Cancer