Kidney, or renal, cancer refers to any cancer that involves the kidney. Advanced age, obesity, and high blood pressure all increase the risk of developing kidney cancer. It is one of the most common cancers in adults.

According to the American Cancer Society (ACS), doctors diagnose around 79,000 new cases of renal cancer each year, mostly before the cancer has spread to another part of the body.

There is no single definitive treatment for renal cancer, as it depends on an individual’s overall health and the stage and type of cancer. However, treatment may include surgery, immunotherapy, or chemotherapy, among others.

Keep reading to learn more about renal cancer, including its causes, diagnosis, treatment, and outlook.

person with hands on their lower backShare on Pinterest
Design by MNT; Photography courtesy of RealPeopleGroup/Getty Images

Renal cancer begins in the kidneys, a pair of bean-shaped organs on either side of the spine behind the stomach. The kidneys filter excess water, salt, and waste products from the blood. They then return the filtered blood to the circulatory system and pass the waste as urine into the bladder.

Cancer begins when cells grow and divide uncontrollably instead of in an organized manner. As a result, the cancerous cells create masses called tumors. These tumors can then invade and damage nearby tissues and organs or spread to other parts of the body.

The ACS reports that renal cancer affects 1 in every 46 men and 1 in every 80 women over a lifetime. Moreover, the average age of diagnosis is typically 64 years old.

Renal tumors

An individual with renal cancer may have tumors in one or both kidneys. Sometimes, renal tumors are benign, meaning they are not cancerous. They may not spread to other areas of the body. However, sometimes they can grow and cause problems. Once these tumors start causing issues, doctors may recommend removing them.

There are various types of renal cell cancers, including:

  • Renal cell carcinoma (RCC): This is the most common type of kidney cancer — accounting for up 90% of cases. It originates in the renal cortex, or the outer layer of the kidney. Doctors can further divide it into several subtypes.
  • Transitional cell carcinoma: Around 5–10% of kidney cancers are of this type. They originate in the renal pelvis, which is the center of the kidney. Doctors may also refer to them as urothelial carcinomas.
  • Wilms tumor: This type of tumor typically occurs in children and is rare among adults. Doctors may also refer to it as nephroblastoma.

Learn more about the different types of kidney cancer here.

Symptoms do not usually appear in the early stage of kidney cancer, but some people still experience them, particularly when the cancer becomes more widespread.

Some symptoms of renal cancer include:

Other diseases may cause similar symptoms. If someone experiences any of these symptoms, they should contact their doctor.

Doctors are unsure of exactly what causes renal cancer, but genetic and environmental factors may play a role.

In the case of renal cancer, cells in the kidney undergo certain changes. Cancer starts when there is a change in the structure of DNA in cells, which can trigger them to grow uncontrollably. Eventually, a tumor will form.

The changes may turn on oncogenes, which are genes that help cells grow, divide, and stay alive. They may also turn off tumor suppressor genes, which keep cell division under control and help cells die at an appropriate time.

If an individual has changes in multiple genes, this could cause kidney cancer.

The primary risk factor for renal cell carcinoma is smoking cigarettes, pipes, and cigars.

Obesity is another major risk factor, particularly among females. Experts estimate that quitting smoking and maintaining a moderate weight can half the incidence of renal cancer.

Other risk factors may include:

The stages of kidney cancer are as follows:

  • Stage 1: The tumor measures less than 7 centimeters (cm) across and is only in the kidney.
  • Stage 2: The tumor is larger than 7 cm but is still in the kidney.
  • Stage 3: The tumor, of any size, has spread outside the kidney. It may have spread to nearby lymph nodes or blood vessels, structures in the kidney that collect urine, or the fatty tissue layer around the kidney.
  • Stage 4: The tumor is growing beyond the fatty layer of the kidney and may grow into the adrenal gland — which is located on top of the kidneys — or nearby lymph nodes. Or, the cancer has spread to other parts of the body.

If a person has symptoms of kidney cancer, a doctor will likely start by:

  • asking about their symptoms
  • asking about their personal and family medical history
  • carrying out a physical examination
  • ordering some tests

Tests

If a doctor suspects that a person might have kidney cancer, they may order one or more of the following tests:

  • Blood and urine tests: These tests can rule out other possible causes of symptoms, such as kidney stones or infection.
  • Imaging scans: An ultrasound, MRI, or CT scan can help the doctor identify the presence of tumors or changes in the shape of the kidney that could be due to cancer.
  • Biopsy: For this procedure, a doctor will use imaging technology to guide them in taking a tissue sample. They will use a needle to remove a small sample of kidney tissue for examination under a microscope. Only a biopsy can confirm the presence of cancer.

The doctor may also recommend other tests to check for transitional cell cancer.

An individual’s treatment options may depend on:

  • their overall health
  • the type and stage of kidney cancer
  • personal preferences
  • previous treatments for cancer

Some options may include:

Surgery

In most cases, surgery is the main treatment for kidney cancer that can be excised. The surgeon may remove part or all of a kidney, as well as tissue from around the tumor. If necessary, they may need to remove lymph nodes and other tissues.

A person can function with just one kidney, so removing a whole kidney is an option.

Laparoscopic surgery, which requires only small incisions, is often possible.

Learn more about surgery for kidney cancer here.

Nonsurgical options

A person who is unwell or frail may not be able to undergo surgery. In this case, some nonsurgical options may be possible if the kidney cancer lesion is considered small — typically no larger than 4 cm.

Cryotherapy/cryoablation: Extremely cold gases pass through a probe, creating an “ice ball” at its tip that can destroy the tumor. The procedure can be painful, and it may cause some bleeding, infection, and damage to the tissue close to the tumor.

Radiofrequency ablation: An electric current is passed through to the tip of a probe to destroy the tumor. It comes with similar risks as cryoablation procedures.

Chemotherapy

Chemotherapy is the use of powerful drugs to attack and kill cancer cells, stopping or delaying the progress of cancer.

Doctors may only prescribe chemotherapy when other treatments, such as immunotherapy or targeted therapies, have not been successful. Kidney cancer cells typically do not respond to chemotherapy, but a small number of people have benefitted from it.

These drugs often affect the whole body, and they can have widespread adverse effects. However, the effects often subside after treatment finishes.

Immunotherapy

Immunotherapy boosts the ability of the body’s immune system to fight cancer.

Inhibitor drugs may target certain proteins found on the immune cells of the body and modify them to attack cancer cells. An example drug is nivolumab (Opdivo), which targets PD-1 protein.

Cytokines, which are small proteins that boost the body’s immune response, may also be an option.

Common side effects include nausea, vomiting, chills, fatigue, and loss of appetite.

Targeted therapy

In targeted therapy, drugs target specific functions or genes that play a role in the development of cancer. They interrupt the functions and proteins that are necessary for cancer to survive and grow.

An example drug is sunitinib (Sutent), which blocks angiogenesis — the process of forming new blood vessels that can feed cancer.

Each drug may come with its own unique side effects, but generally, these types of drugs may cause fatigue, low red blood cell counts, and mouth sores, among other effects.

Radiation therapy

Radiation therapy cannot usually cure kidney cancer. However, it may help shrink a tumor, reduce the spread of cancer cells, and ease symptoms.

It involves using high energy beams to kill cancer cells.

Side effects typically include nausea and fatigue.

Supportive care

Supportive care — or palliative care — can help people with kidney cancer and their families deal with practical, emotional, and physical challenges that come with the diagnosis and treatment process.

Getting an early diagnosis generally improves a person’s outlook. Medical experts use past statistics to calculate how likely people with cancer are to live at least 5 years after diagnosis compared with those in the overall population.

For kidney cancer, the ACS reports the following statistics for 5-year survival rate:

  • 93% for cancer that has not spread beyond the kidneys at diagnosis
  • 71% for cancer that has affected nearby tissues
  • 14% for cancer that has reached other parts of the body

Many different factors affect these estimates, including the type of kidney cancer and the age and overall health of the individual.

For all stages, the overall survival rate at 5 years following diagnosis is 76%.

Learn more about the outlook for kidney cancer and get some tips on living with this disease.

Renal cancer happens when cells grow uncontrollably in the kidneys and form tumors. There are different types of renal cancer, and renal cell carcinoma is the most common.

Smoking, obesity, and a family history of kidney cancer may increase an individual’s chance of developing renal cancer. However, doctors are unsure of the precise causes.

Treatment for renal cancer may involve surgery, systemic treatments, or radiation therapy. These approaches are successful for most people as renal cancer has a general survival rate of 76%.