Kidney cancer

Kidney cancer, also called renal cancer, is the sixth most common cancer in American men and ninth most common in U.S. women. An estimated 76,080 Americans will be diagnosed with kidney cancer in 2021, and more than 4 percent of all new cancers diagnosed are kidney cancers, according to the National Cancer Institute (NCI).

The kidneys are a pair of bean-shaped organs located on either side of the spine, protected by the lower rib cage. Although the body has two kidneys, only part of one kidney is necessary to function. The main job of the kidneys is to filter blood and remove excess water, salt and other substances from the body. Most of these fluids run through tubes called renal tubules, which filter fluids in the kidney before the waste (urine) is discharged into the bladder. Most kidney tumors form when the cells that line these tubules (renal cells) mutate and grow out of control. Renal cell carcinoma is the most common type of kidney cancer.

Renal cell cancer accounts for about 90 percent of cancers in the kidney, according to the American Cancer Society (ACS). Transitional cell carcinoma accounts for about 5 to 10 percent of cancers. Wilms tumor is a rare type of kidney cancer that occurs in children.

Why kidney cells develop into cancer cells isn’t well understood. However, some of the risk factors for kidney cancer are known.

For example, men are twice as likely to be diagnosed with kidney cancer as women. Other unavoidable risk factors include:

• Family history of kidney disease
• Rare genetic disease that increases the risk
• Dialysis for long-term kidney cancer
• Long-term exposure to asbestos, cadmium or the pain medication phenacetin (taken off the market in the 1970s)

Some risk factors for kidney cancer may be managed, including:

• Smoking
• High blood pressure
• Obesity

Learn more about risk factors for kidney cancer

As with most cancers, the risk for developing kidney cancer increases with age. According to the NCI and ACS:

• The average age of a person diagnosed with kidney cancer is 64.
• The median age of a person who dies from kidney cancer is 72.
• Most people diagnosed with kidney cancer are between 65 and 74.
• Kidney cancer is about twice as common in men than in women, and African Americans, American Indian and Alaskan Natives are more likely to be diagnosed.

Signs and symptoms of kidney cancer don’t usually become noticeable until late in the disease. In the early stages, there are usually no symptoms. If they do develop, they may include:

• Pain in back or side
• Swelling or lump in back or side
• Blood in the urine
• Fatigue
• Swelling in the ankles
• Loss of appetite and unexplained weight loss
• Rapid swelling in the testicle area for men
• Unexplainable fevers that come and go

Signs of kidney cancer caused by changes in kidney hormones may include:

• High blood pressure
• Anemia

Learn more about kidney cancer symptoms

More than 90 percent of all kidney tumors are renal cell carcinomas (RCC). Subtypes include:

• Clear cell RCC
• Papillary RCC
• Chromophobe RCC
• Collecting duct RCC
• Unclassified RCC

Other types of kidney cancer include:

• Transitional cell carcinoma
• Renal sarcoma

Metastatic renal cancer occurs when the cancer has spread from the kidney into lymph nodes or distant organs, such as the liver, lungs or bladder.

Learn more about kidney cancer types

Many early kidney cancers are discovered during testing for other reasons. A urine sample may show blood, or a blood test may detect anemia. An imaging study of the abdomen for unrelated symptoms may reveal kidney cancer.

If doctors suspect kidney cancer, imaging studies are important for diagnosis. In some cases, kidney cancer may be diagnosed with imaging studies alone.

These include:

• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Ultrasound imaging

If surgery is recommended, the diagnosis also may be confirmed post-op by looking at cancer cells under a microscope, called pathologic diagnosis. Kidney cancer also may be confirmed with a needle biopsy.

Learn more about diagnosing kidney cancer

The next step after diagnosis is to determine the stage of cancer. The stage helps doctors select the most appropriate treatment options.

To find the stage, additional tests such as a chest X-ray or bone scan may be ordered, which helps determine whether the cancer has spread to the lungs or bones.

There are four stages for kidney cancer:

• In stage 1, the cancer is in the kidney and isn’t larger than 7 cm.
• In stage 2, the cancer is still only in the kidney but is larger than 7 cm.
• In stage 3, the cancer may be any size and has spread to nearby lymph nodes; or it has spread to blood vessels near or in the kidney or to the layer of fatty tissues surrounding the kidney.
• In stage 4, the cancer has spread away from the kidney to the adrenal gland (a gland that sits on top of the kidney) or to distant lymph nodes or organs.

Learn more about kidney cancer stages

Surgery is the first-line treatment option for most patients with renal cell carcinoma. Other treatment options for all types of kidney cancer include:

• Chemotherapy
• Radiation therapy
• Targeted therapy
• Immunotherapy 

Learn more about treatments for kidney cancer

Kidney cancer is the sixth most common type of cancer among men and the ninth among women, according to the American Society of Clinical Oncology (ASCO). Seventy-five percent of people live at least five years after a kidney cancer diagnosis. It’s important to remember actual survival depends on the stage of cancer and the body’s response to treatment.

The ASCO also reports a 93 percent five-year survival rate if someone is diagnosed with cancer confined explicitly to the kidney. If cancer has spread outside the kidney to nearby structures, the five-year survival rate is 70 percent.

When cancer has spread to distant areas of the body, the five-year survival rate drops to 13 percent. It’s important to understand that newer treatments over the last five years may improve survival rates.