Kidney cancer is cancer that originates in the kidneys. Your kidneys are two bean-shaped organs, each about the size of your fist. They’re located behind your abdominal organs, with one kidney on each side of your spine.
Kidney cancer also called renal cancer is a disease in which kidney cells become malignant (cancerous) and grow out of control, forming a tumor. Almost all kidney cancers first appear in the lining of tiny tubes (tubules) in the kidney. This type of kidney cancer is called renal cell carcinoma. The good news is that most of the kidney cancers are found before they spread (metastasize) to distant organs. And cancers caught early are easier to treat successfully. However, these tumors can grow to be quite large before they are detected.
In adults, the most common type of kidney cancer is renal cell carcinoma. Other less common types of kidney cancer can occur. Young children are more likely to develop a kind of kidney cancer called Wilms’ tumor.
The incidence of kidney cancer seems to be increasing. One reason for this may be the fact that imaging techniques such as computerized tomography (CT) scan are being used more often. These tests may lead to the accidental discovery of more kidney cancers.
Kidney cancer staging
Once your doctor identifies a kidney lesion that might be kidney cancer, the next step is to determine the extent (stage) of cancer. Staging tests for kidney cancer may include additional CT scans or other imaging tests your doctor feels are appropriate.
Then your doctor assigns a number, called a stage, to your cancer. Kidney cancer stages include:
- Stage I. At this stage, the tumor can be up to 2 3/4 inches (7 centimeters) in diameter. The tumor is confined to the kidney.
- Stage II. A stage II kidney cancer is larger than a stage I tumor, but it’s still confined to the kidney.
- Stage III. At this stage, the tumor extends beyond the kidney to the surrounding tissue and may also have spread to a nearby lymph node.
- Stage IV. Cancer spreads outside the kidney, to multiple lymph nodes or to distant parts of the body, such as the bones, liver or lungs
It’s not clear what causes renal cell carcinoma. Doctors don’t know the causes of kidney cancer but know that kidney cancer begins when some kidney cells acquire mutations in their DNA. The mutations tell the cells to grow and divide rapidly. The accumulating abnormal cells form a tumor that can extend beyond the kidney. Some cells can break off and spread (metastasize) to distant parts of the body.
Symptoms of Kidney Cancer
Kidney cancer rarely causes signs or symptoms in its early stages. As the tumor grows larger, symptoms may appear. You may have one or more of these kidney cancer symptoms:
- Blood in your urine
- A lump in your side or abdomen
- A loss of appetite
- A pain in your side that doesn’t go away
- Weight loss that occurs for no known reason
- Fever that lasts for weeks and isn’t caused by a cold or other infection
- Extreme fatigue
- Swelling in your ankles or legs
- Back pain just below the ribs that doesn’t go away
Kidney cancer that spreads to other parts of your body may cause other symptoms, such as:
- Shortness of breath
- Coughing up blood
- Bone pain
How do I know if I have kidney cancer?
Maybe you’ve had kidney cancer symptoms such as pain in your side, weight loss, or extreme fatigue. Or maybe your doctor has found a lump in your side during a routine exam or a sign of kidney cancer during a test for another disease. Regardless, to confirm a diagnosis of kidney cancer, you will need a thorough physical exam, health history, and tests.
Your doctor will feel your abdomen and side for lumps and check for fever and high blood pressure, among other things. You will also answer questions about your health habits, any past illnesses, and types of treatment.
Factors that can increase the risk of kidney cancer include:
- Smoking. If you smoke cigarettes, your risk for kidney cancer is twice that of nonsmokers. Smoking cigars may also increase your risk.
- Being male. Men are about twice as likely as women to get kidney cancer.
- Being obese. Extra weight may cause changes to hormones that increase your risk.
- Using certain pain medications for a long time. This includes over-the-counter drugs in addition to prescription drugs.
- Having advanced kidney disease or being on long-term dialysis, a treatment for people with kidneys that have stopped working
- Having certain genetic conditions, such as von Hippel-Lindau (VHL) disease or inherited papillary renal cell carcinoma
- Having a family history of kidney cancer. The risk is especially high in siblings.
- Being exposed to certain chemicals, such as asbestos, cadmium, benzene, organic solvents, or certain herbicides
- Having high blood pressure. Doctors don’t know whether high blood pressure or medication used to treat it is the source of the increased risk.
- Being black. The risk in blacks is slightly higher than in whites. No one knows why.
- Having lymphoma. For an unknown reason, there is an increased risk of kidney cancer in patients with lymphoma.
- Older age. Your risk of kidney cancer increases as you age.
- Treatment for kidney failure. People who receive long-term dialysis to treat chronic kidney failure have a greater risk of developing kidney cancer.
- Certain inherited syndromes. People who are born with certain inherited syndromes may have an increased risk of kidney cancer, including those who have von Hippel-Lindau disease, Birt-Hogg-Dube syndrome, tuberous sclerosis and familial papillary renal cell carcinoma.
Having these risk factors does not mean you will get kidney cancer. And it’s also true that you can have none of them and still get the disease.
Diagnosing kidney cancer:
Tests and procedures used to diagnose kidney cancer include:
- Urine tests: check for blood in your urine or other signs of problems.
- Blood tests: show how well your kidneys are working.
- Intravenous pyelogram (IVP): involves X-raying your kidneys after the doctor injects a dye that travels to your urinary tract, highlighting any tumors.
- Ultrasound: uses sound waves to create a picture of your kidneys. It can help tell if a tumor is solid or fluid-filled.
- A CT scan: uses X-rays and a computer to create a series of detailed pictures of your kidneys. This may also require an injection of dye. CT scans have virtually replaced pyelogram and ultrasound as a tool for diagnosing kidney cancer.
- Magnetic resonance imaging (MRI): uses strong magnets and radio waves to create detailed images of soft tissues in your body. You may need an injection of a contrast agent to create better pictures.
- Removing a sample of kidney tissue (biopsy). In rare cases, your doctor may recommend a procedure to remove a small sample of cells (biopsy) from a suspicious area of your kidney. The sample is tested in a lab to look for signs of cancer.
- Renal arteriogram: This test is used to evaluate the blood supply to the tumor. It is not given often, but may help diagnose small tumors. It has other uses, as well.