The kidneys are two bean-shaped organs, each about the size of a fist. They’re located in your abdomen on either side of your spine. The kidneys filter out waste from your blood and make urine. There are different types of cancer that can affect your kidneys.

The National Cancer Institute (NCI) estimates that there were more than 76,000 new cases of kidney cancer diagnosed in the United States in 2021, making up about 4 percent of all new cancers diagnosed for that year.

While the incidence of kidney cancer appears to be increasing, the NCI also notes a steadily decreasing death rate from this cancer. This may be possibly attributed to earlier detection, as well as new treatments.

Read on to learn important facts about kidney cancer you can discuss with your doctor, including possible symptoms, causes, treatments, and more.

Kidney cancer doesn’t usually cause any symptoms in its early stages when the mass is small. As the cancer progresses, the symptoms may include:

While there are numerous risk factors for kidney cancer, there aren’t any specific known causes.

What is known about the evolution of kidney cancer is that it’s similar to the development of all cancers — in that it begins with abnormal cells in the body that grow and develop into tumors.

Cancers also get their names for the place they first start. So with kidney cancer, these abnormal cells first develop in your kidneys and may spread to other areas of the body.

According to the Centers for Disease Control and Prevention (CDC), smoking is the most prevalent risk factor for developing kidney cancer. Other possible risk factors for kidney cancer can include:

There are also several inherited conditions that can increase your risk of kidney cancer. These include von Hippel-Lindau disease, hereditary papillary renal cell carcinoma, and tuberous sclerosis.

Several types of cancer can affect the kidneys:

Renal cell carcinoma (RCC)

RCC is also known as renal cell adenocarcinoma. As many as 9 out of 10 kidney cancers are this type, making RCC is the most common type of kidney cancer, according to the American Cancer Society (ACS). It starts in the part of the kidney that filters blood and usually involves a single tumor on one kidney.

It most commonly affects men ages 50 to 70.

Clear cell renal cell carcinoma

This RCC subtype makes up an estimated 7 out of 10 cases of RCC. It’s called “clear cell” due to the pale or clear appearance of the cells in a lab.

Non-clear cell renal cell carcinomas

This RCC subtype is rarer and doesn’t appear clear under a microscope. Non-clear cell renal cell carcinomas include two types: papillary RCC and chromophobe RCC.

Renal pelvis carcinoma

Renal pelvis carcinoma starts in the part of the kidney where urine is collected.

Renal sarcoma

While not as common, renal sarcoma is a type of kidney cancer that starts in connective tissues or blood vessels.

Wilms’ tumor

Wilms’ tumor is considered a non-clear cell RCC. It is the most common type of kidney cancer in children under the age of 5 and may also occur in some adults.

Types of kidney cancer that are considered rare can include:

  • collecting duct RCC
  • multilocular cystic RCC
  • neuroblastoma-associated RCC
  • medullary carcinoma
  • mucinous tubular and spindle cell carcinoma

A diagnosis of kidney cancer requires a complete history and physical exam. Your doctor will look for an abdominal swelling or a lump in your abdomen. In men, the doctor may also look for an enlarged, twisted vein, or varicocele, in the scrotum.

Some diagnostic tests that can be used to detect kidney cancer can include:

Urinalysis

A urinalysis can allow your doctor to determine if there’s blood present in your urine. It may also reveal other signs of an infection. Cancer cells may also be detected this way.

Complete blood count

The kidneys produce a hormone called erythropoietin that stimulates the production of red blood cells. A complete blood count can reveal if the red blood cell count is high, which would indicate polycythemia. Polycythemia occurs when the body overproduces red blood cells, which can thicken the blood and potentially lead to other complications.

Blood chemistry tests

Blood chemistry tests can help show how well your kidneys are functioning. Kidney cancer can also influence the levels of some types of chemicals in your blood, such as liver enzymes and calcium.

Ultrasound of the abdomen and kidneys

An abdominal ultrasound can measure the size and shape of your kidneys. If a tumor is present, it may reveal its size and consistency. Sometimes, an ultrasound may miss small masses or small kidney stones so another imaging test may be used.

Renal angiography (areteriogram)

In this test, your doctor threads a catheter up a large artery in your leg or groin, to the renal artery. They’ll inject a special dye into the artery. After the dye is injected, they’ll take a series of X-rays. This helps your doctor see the blood supply to your kidneys in detail. If a tumor is present, the blood supply to the tumor can be seen.

Intravenous pyelogram

In this test, a healthcare professional will inject a special dye into one of your veins. The dye allows your kidneys to be seen more clearly with X-rays. This test can help your doctor find a tumor or obstruction.

CT scan of the abdomen

A CT scan is a noninvasive test that uses X-rays to create cross-sectional images of your body. It allows the following to be viewed:

  • bones
  • muscles
  • fat
  • organs
  • blood vessels

It can be used to find out if cancer has spread beyond the kidney.

The following tests can also be used to find out if kidney cancer has spread:

Staging kidney cancer is important to determine how large of a tumor is present, where the tumor currently is, and whether the cancer has spread. All of these factors are considered in determining your treatment options, too.

Kidney cancer is staged based on the following factors:

  • Stage I: Stage I kidney cancer is limited to the kidney. At this stage, the tumor is less than 7 centimeter (cm) in diameter.
  • Stage II: The tumor may be larger than 7 cm on one kidney in this stage, or has spread to the fat or tissues of the kidney. The cancer hasn’t spread to the lymph nodes or other organs.
  • Stage III: The tumor may be any size and may extend to the blood vessels. It hasn’t spread to lymph nodes or other organs.
  • Stage IV: At stage IVa, the tumor may have spread to adrenal glands, nearby lymph nodes, or adjacent organs. A designation of stage IVb indicates the cancer has spread or metastasized to distant lymph nodes and organs.

The treatment for kidney cancer focuses on removing the tumor from your body. This is usually done through surgery. Surgery can be radical or conservative.

However, metastatic kidney cancer — kidney cancer that has spread to other parts of the body — can’t be treated with surgery alone. After as much tumor is removed as possible with surgery, other treatments may be necessary. These may include immunotherapy, targeted therapy, and radiation.

Radical nephrectomy

A radical nephrectomy is a surgical procedure that removes your kidney. The entire organ is removed, along with some surrounding tissue and lymph nodes. The adrenal gland may be removed as well. The surgery can be done through a large incision or with a laparoscope, which consists of a thin tube with a tiny camera at one end.

Conservative nephrectomy

Conservative nephrectomy removes only the tumor, lymph nodes, and some surrounding tissue. Part of the kidney is left behind. This is also known as a nephron-sparing nephrectomy. Tumor cells can also be destroyed by freezing, which is called cryosurgery, or radiofrequency ablation, which involves applying heat.

Radiation therapy

Radiation therapy may be used to damage or destroy cancer cells with high-energy waves. This may stop them from growing and spreading. Radiation is often performed to target cancer cells that may remain after surgery. It is considered a local treatment, which means it is often used for just a specific area of the body.

Chemotherapy

Chemotherapy is a chemical drug therapy used to treat cancer. It targets rapidly growing cancer cells and affects the whole body. It may be recommended by a doctor if the cancer has spread, or metastasized, from the kidneys to other parts of the body.

Immunotherapy

Immunotherapy is a special treatment that helps your own immune system recognize the cancer cells and fight the cancer more effectively. Examples of immunotherapy used to treat kidney cancer include Pembrolizumab (Keytruda) and Nivolumab (Opdivo).

Targeted drugs

Targeted drugs are designed to block certain abnormal signals present in kidney cancer cells. They can help stop the formation of new blood vessels to supply nutrients to the cancer cells. Examples of targeted drugs include:

  • axitinib (Inlyta)
  • lenvatinib (Lenvima)
  • pazopanib (Votrient)
  • sorafenib (Nexavar)
  • sunitinib (Sutent)

Clinical Trials

Clinical trials may offer additional options for those with kidney cancer. They test treatment options that have not yet been approved by the U.S. Food and Drug Administration (FDA) for a specific diagnosis. Clinical trials can provide an additional option for people who have not had success with other options.

In some cases, clinical trials may be covered by insurance or paid by a sponsor that covers the cost for participants.

Many of today’s cancer treatments also started out as clinical trials. If you’re interested in participating in a clinical trial for kidney cancer treatment, ask your doctor or look for clinical trials near you.

The outlook for people with kidney cancer varies. It depends on how quickly the cancer is caught and how it responds to treatment.

Approximately 65 percent of kidney and renal pelvis cancers are diagnosed before they have spread. The cancer may spread, or metastasize, to the other kidney. However, it’s most likely to spread to the lungs. Metastatic cancer can be harder to treat.

Kidney cancer can also be complicated by:

Survival rates for kidney cancer are higher when the condition is treated in its earlier stages. For example, the ACS reports that the observed five-year survival rate for stage 1 kidney cancer is 80 percent. Keep in mind that observed survival rates are estimates. They are based on groups of people.

The outlook for an individual with kidney cancer can depend on their age, overall health, other health conditions, the stage of the cancer when it is diagnosed, and how far it has spread.

Living a healthy lifestyle is the best way to reduce your risk of kidney cancer. Specific steps you can take to reduce your risk may include:

Kidney cancer most often begins in just one of the kidneys. You may still experience early symptoms such as back pain or blood in your urine. It’s important to keep up with your annual wellness visits and to consult with your doctor right away if you’re experiencing any unusual symptoms.

While the exact cause of kidney cancer is unknown, many factors can increase your risk, such as smoking, obesity, and an unhealthy diet. Talk with your doctor about any risk factors you might have for kidney cancer, as well as your treatment options if you’re diagnosed with this type of cancer.