Definition
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. In adults, the most common type of kidney cancer is renal cell carcinoma. Other less common types of kidney cancer can occur, including Wilms’ tumor, which is more common in young children.

Kidney Mass Types: Cysts vs. Tumors
There are several types of kidney masses, including cysts and tumors. Kidney masses can be benign (non-cancerous) or malignant (cancerous).

Kidney cysts
Kidney cysts are fluid-filled sacs in the kidney, and they can be simple or complex. They can be given a Bosniak classification to help determine if they carry a risk of cancer. Simple cysts (Bosniak I) carry a 0% risk of cancer. Complex cysts are classified as Bosniak II, III, or IV. Bosniak II cysts carry a 15-25% risk of cancer. Bosniak III cysts carry a 50-70% risk of cancer. Bosniak IV cysts carry a 90-100% risk of cancer.

Kidney tumors
There are many types of kidney tumors. Kidney tumors can be benign (non-cancerous) or malignant (cancerous). Imaging and tests can help Dr. Gholami determine if a kidney tumor is likely benign or malignant.

Signs and Symptoms
Kidney cancer rarely causes signs or symptoms in its early stages, which is why the majority of kidney masses are detected incidentally. In the later stages, kidney cancer signs and symptoms may include:

• Blood in your urine (hematuria)
• Back and/or flank pain
• Weight loss
• Fatigue
• Intermittent fever

Causes and Risk Factors
It’s not clear what causes renal cell carcinoma. Doctors 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 mass that can extend beyond the kidney. Some cells can break off and spread (metastasize) to distant parts of the body.

Factors that can increase the risk of kidney cancer include:

• Older age. Your risk of kidney cancer increases as you age.
• Being male. Men are more likely to develop kidney cancer.
• Smoking. Smokers have a greater risk of kidney cancer than nonsmokers do. The risk decreases after you quit.
• Obesity. People who are obese have a higher risk of kidney cancer than do people who are considered average weight.
• High blood pressure (hypertension). High blood pressure increases your risk of kidney cancer.
• Chemicals in your workplace. Workers who are exposed to certain chemicals on the job may have a higher risk of kidney cancer. Some evidence suggests people who work with chemicals such as asbestos and cadmium may have an increased risk of kidney cancer.
• Treatment for kidney failure. People who receive long-term dialysis to treat chronic kidney failure have a greater risk of developing kidney cancer.
• Von Hippel-Lindau disease. People with this inherited disorder are likely to develop several kinds of tumors, including, in some cases, kidney cancer.
• Hereditary papillary renal cell carcinoma. Having this inherited condition makes it more likely you’ll develop one or more kidney cancers.

Tests
Dr. Gholami uses the following tests for kidney masses:

• Computerized tomography (CT) scan – of the abdomen and pelvis. A CT scan allows Dr. Gholami to visualize your kidney mass. This helps him to view your anatomy and make the best treatment recommendation for you.
• Ultrasound – renal/bladder. Like a CT scan, an ultrasound allows Dr. Gholami to visualize your kidney mass. He may recommend this imaging for you, however a CT scan generally provides Dr. Gholami with better information about your anatomy.
• Blood and urine tests (urinalyses). Tests of your blood and your urine can give Dr. Gholami clues about what’s causing your symptoms.