Kidney cancer

Introduction

Your kidneys are two bean-shaped organs, each about the size of your fist. They're located behind your abdomen, one on each side of your spine. Like other major organs in the body, the kidneys can sometimes develop cancer. In adults, the most common type of kidney cancer is renal cell carcinoma (renal adenocarcinoma), which begins in the cells that line the small tubes within your kidneys. Children are more likely to develop a kind of kidney cancer called Wilms' tumor.

Kidney cancer seldom causes problems in its early stages. But as a tumor grows, you may notice blood in your urine or experience unintentional weight loss or back pain that doesn't go away. Kidney cancer cells may also spread (metastasize) outside your kidneys to nearby organs as well as to more distant sites in the body. Yet if kidney cancer is detected and treated early, the chances for a full recovery are good.

Signs and symptoms

Kidney cancer rarely causes signs or symptoms in its early stages. In the later stages, the most common sign of both renal cell and transitional cell cancers is blood in the urine (hematuria). You may notice the blood when you urinate, or your doctor may detect it by urinalysis, a test that specifically checks the contents of your urine. Other possible signs and symptoms may include:

• A pain in the back just below the ribs that doesn't go away
• A mass in the area of the kidneys that's discovered during an examination
• Weight loss
• Fatigue
• Intermittent fever
• Pain in other parts of the body if the cancer has metastasized

Wilms' tumor usually has no symptoms, and doctors are likely to discover this condition when examining a child's abdomen.

Renal cell carcinoma, which accounts for most kidney cancers, usually begins in the cells that line the small tubes (tubules) that make up a part of each nephron. In most cases, renal cell tumors grow as a single mass, but you may have more than one tumor in a kidney or develop tumors in both kidneys.

A far less common type of kidney cancer, transitional cell carcinoma, develops in the tissue that forms the tubes connecting the kidneys to the bladder. Transitional cell carcinomas can also begin in the ureters themselves or in the bladder. A rare form of kidney cancer, renal sarcoma, begins in the connective tissue of the kidney.

Just what causes kidney cells to become cancerous isn't clear. But researchers have identified certain factors that appear to increase the risk of developing both renal and transitional cell kidney cancers..

Prevention

Although the following steps may not prevent kidney cancer, they can help reduce your cancer risk and keep you healthier overall:

• Quit smoking. Smokers are nearly twice as likely to develop kidney cancer as nonsmokers are. Talk to your doctor about the best ways to stop smoking.
• Eat more fruits and vegetables. In the past, some studies have shown that a diet rich in fruits and vegetables may help protect against kidney cancer. A 2005 Swedish study looked at which types of produce might offer the most benefits. The study found an overall association between consumption of fruits and vegetables and a lower risk of kidney cancer. Further, the study found the strongest association was for study participants eating bananas and root vegetables, including beets and carrots.
• Stay physically active. An active lifestyle reduces your risk of kidney cancer and helps you lower your blood pressure and maintain a healthy weight. Aim for at least 30 minutes of exercise on most days. If you haven't been active before, start out slowly, and gradually increase the amount of time you exercise. Try to include weight-bearing exercises, such as walking, jogging or dancing as well as some strength-training exercises in your routine. Strength training has been found to reduce stress even more than aerobic exercise does, and it has the added benefit of helping keep your bones strong.
• Maintain a healthy weight. There is a clear link between weighing more than is healthy for you and kidney cancer.
• Reduce or avoid exposure to environmental toxins. If you must work with toxic chemicals, take special precautions such as wearing a mask and heavy gloves.
• Reduce high blood pressure. If you have, or think you may have, high blood pressure — which has been linked to renal cell carcinoma in men — talk to your doctor. Diet and exercise can control high blood pressure in many cases.