Most cancers are named after the part of the body where the cancer first begins, and kidney cancer is no exception. Kidney cancer begins in the kidneys—two large, bean-shaped organs—one located to the left, and the other to the right of the backbone. Renal is the Latin word for kidney, and kidney cancer may also be referred to as renal cancer.

According to the American Cancer Society (ACS), about 81,800 people in the U.S. are expected to be diagnosed with kidney and renal pelvic cancers in 2023. The most common type is called renal cell cancer. The information contained on this page refers to renal cell cancer.

What are the risk factors for renal cell cancer?

The exact cause of renal cell cancer is unknown. However, there are certain risk factors that are linked to it. These risk factors, according to the ACS, are as follows:

• Smoking. Smoking increases the risk of kidney cancer. The risk seems related to the amount you smoke.
• Asbestos. Studies show a link between exposure to asbestos and kidney cancer.
• Cadmium. There may be a link between cadmium exposure and kidney cancer. Cadmium may increase the cancer-causing effect of smoking.
• Family history. Family history of kidney cancer increases a person's risk.
• Gender. Men are twice as likely to develop renal cell cancer than women.
• Von Hippel-Lindau syndrome. This is a disease caused by a gene mutation that increases the chances of renal cell cancer.
• Birt-Hogg-Dube syndrome. Patients who have this disease are more likely to develop renal cell cancer.
• Other hereditary syndromes. Patients with hereditary papillary renal cell carcinoma, hereditary leiomyoma-renal cell carcinoma, and hereditary renal oncocytoma are more likely to develop kidney cancer.
• Obesity. Obesity increases a person's risk of kidney cancer.
• Advanced kidney disease. Patients with advanced kidney disease who have been on dialysis for a long time may develop renal cell cancer.
• High blood pressure. Patients who have high blood pressure have a higher risk for kidney cancer.
• Diuretics (water pills). Drugs that eliminate excess body fluid may raise the risk of kidney cancer, although this is not clear.
• Race. African-Americans have a slightly higher risk of kidney cancer.

What are the symptoms of renal cell cancer?

The following are the most common symptoms of renal cell cancer. However, each individual may experience symptoms differently. Symptoms may include:

• Blood in the urine
• Rapid, unexplained weight loss
• Low back pain (not caused by an injury)
• Loss of appetite
• Swelling of ankles and legs
• Mass or lump on the side or lower back
• Fatigue
• Recurrent fever (not caused by a cold or the flu)
• High blood pressure (less frequently)
• Anemia (less frequently)
• Unrelieved pain in the side

The symptoms of renal cell cancer may resemble other conditions or medical problems. Always consult your doctor for a diagnosis.

How is kidney cancer (renal cell cancer) diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for kidney cancer may include the following:

• Blood and urine laboratory tests
• Intravenous pyelogram (IVP). A series of X-rays of the kidney, ureters, and bladder with the injection of a contrast dye into the vein to detect tumors, abnormalities, kidney stones, or any obstructions, and to assess renal blood flow.
• Renal angiography (also called arteriography). A series of X-rays with the injection of a contrast dye into a catheter, which is placed into the blood vessels of the kidney, to detect any signs of blockage or abnormalities affecting the blood supply to the kidneys.
• Other imaging tests (to show the difference between diseased and healthy tissues), including the following:
• Computed tomography scan (also called a CT or CAT scan). A noninvasive type of X-ray procedure that takes horizontal, or axial, images of the brain or other internal organs to detect any abnormalities that may not show up on an ordinary X-ray.
• Magnetic resonance imaging (MRI). A noninvasive procedure that uses radio waves and strong magnets to produce very detailed two-dimensional views of an internal organ or structure, especially the brain and spinal cord.
• Ultrasound (also called sonography). A diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
• Chest X-ray. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs on film.
• Bone scan. A nuclear imaging method to evaluate any degenerative and/or arthritic changes in the joints to detect bone diseases and tumors to determine the cause of bone pain or inflammation.

Based on results of other tests and procedures, a biopsy may be needed. A biopsy is a procedure in which a sample of the tumor is removed and sent to the laboratory for examination by a pathologist.

What are the different types of kidney cancer?

The main type of kidney cancer is called renal cell carcinoma (RCC). About 9 out of 10 kidney cancer tumors are this type. If you have this type of kidney cancer, you may have more than one tumor in one or both kidneys. These may be large by the time they are diagnosed. But most cases of kidney cancer are found before the cancer has spread to other organs.

There are different types of RCC. A healthcare provider called a pathologist identifies these types by looking at the cancer cells under a microscope. The types of RCC include:

• Clear cell. This is the most common type of RCC. The cancer cells look pale or clear.
• Papillary. This is the second most common type of RCC. This type of tumor has tiny fingerlike growths.
• Chromophobe. This is a rare form of RCC. The cells are larger than other types of RCC.
• Clear cell Papillary. Recently recognized and usually less aggressive variant of kidney cancer
• Collecting duct. This is also a rare form of RCC. The cancer cells look like irregular tubes.
• Unclassified. This includes tumors that have cells from more than 1 type of cancer. It also includes tumors with cells that don’t fit into the other categories.

Other types of kidney cancer

Other less-common types of kidney cancers include:

• Transitional cell carcinoma. This is also known as urothelial carcinoma and unlike other kidney cancers, forms in the tubes that drain the kidney. These tubes have the same lining as the bladder and thus this type of kidney cancer can act and look like bladder cancer.
• Wilms’ tumor. This cancer most always occurs in children. It's very rare in adults.
• Renal sarcoma. This is a very rare type of kidney cancer. It begins in the blood vessels and connective tissue around the kidneys.

Kidney tumors that aren’t cancer

There are several types of kidney tumors that are not cancer (benign). These include renal cell adenoma, renal oncocytoma, and angiomyolipoma. Oncocytomas are the most common benign tumors but are often difficult to distinguish from kidney cancers. All these benign tumors may still affect kidney function and can cause pain and other symptoms. But the cells usually do not spread to other organs.

How is kidney cancer treated?

Specific treatment for kidney cancer will be determined by your doctor based on:

• Your age, overall health, and medical history
• Extent of the disease
• Your tolerance for specific medications, procedures, or therapies
• Expectations for the course of the disease
• Your opinion or preference

Treatment may include:

• Surgical removal of the tumor or nephrectomy is the most common treatment for kidney cancer. These procedures can be performed minimally invasive (laparoscopic or robotic) or with open surgery. The following are different types of nephrectomy procedures:
• Radical nephrectomy. The whole kidney is removed (with the tumor inside) as a package together with the adrenal gland, tissue around the kidney, and sometimes, lymph nodes in the area. This is usually performed for larger tumors. If performed, the remaining kidney is generally able to perform the work of both kidneys.
• Simple nephrectomy. Only the kidney is removed.
• Partial nephrectomy. Only the part of the kidney that contains the tumor is removed. This is the preferred for smaller localized tumors.

Other therapies

• Ablation therapy. A less invasive option to treat small tumors using thermal energy in well selected patients. This is usually done with image guidance such as CT.
• Radiation therapy. Radiation therapy uses high-energy X-rays to kill cancer cells, and is also sometimes used to relieve pain when kidney cancer has spread to the bone.
• Targeted therapy. Targeted therapy uses drugs that attack specific parts of cancer cells. These drugs work differently from standard chemotherapy drugs, and often have less severe side effects. They are commonly the first line of treatment for advanced kidney cancer. Examples include sunitinib (Sutent), sorafenib (Nexavar), temsirolimus (Torisel), everolimus (Afinitor), bevacizumab (Avastin) and pazopanib (Votrient).
• Biological therapy (also called immunotherapy). Biological therapy is a treatment that uses the body's own immune system to fight cancer.
• Chemotherapy. Chemotherapy is the use of drugs to kill cancer cells. Unfortunately, kidney cancer is often resistant to chemotherapy drugs.
• Arterial embolization. Arterial embolization is a procedure in which small pieces of a special gelatin sponge, or other material, are injected through a catheter to clog the main renal blood vessel. This procedure shrinks the tumor by depriving it of the oxygen-carrying blood and other substances it needs to grow. It may also be used before an operation to make surgery easier, or to provide relief from pain when removal of the tumor is not possible.

If you or a family member has been diagnosed with kidney cancer, you may want to consider getting a second opinion. In fact, some insurance companies require a second opinion for such diagnoses. According to the ACS, it's rare that the time it will take to get a second opinion will have a negative impact on your treatment. The peace of mind a second opinion provides may be well worth the effort.