AUA Summit - What is Kidney Cancer?


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What is Kidney Cancer?

Our kidneys’ main job is to filter our blood. Sometimes we develop masses (growths or tumors) inside our kidneys.  Some of these growths are cancerous but many are not. You must have your mass checked out to learn if it is cancerous or not. 

There are many different options for treatment. Often there are even more choices if your cancer is found early. Your medical team is there to help you. They can help you learn more about the pros and cons of treatments. Here we share more about kidney cancer and the steps you can take if a mass forms in your body.

What is the Purpose of our Kidneys?

Our kidneys serve many purposes, but they mainly do the following:

  • Detoxify (clean) our blood
  • Balance fluids
  • Maintain electrolyte levels (e .g ., sodium, potassium, calcium, magnesium, acid)
  • Remove waste (as urine)
  • Make hormones that help keep our blood pressure stable, make red blood cells and keep our bones strong

What is a Kidney Mass?

A tumor, or mass, is an abnormal growth in the body. A kidney mass, or tumor, is an abnormal growth in the kidney. Some kidney masses are benign (not cancerous) and some are malignant (cancerous).

One in four kidney masses are benign. Smaller masses are more likely to be benign. Larger masses are more likely to be cancerous. Some tumors may grow slowly while some can be faster growing – or more aggressive. Aggressive tumors may form, grow and spread very quickly.

Most kidney growths (about 40%) are small, localized masses.  Localized means that the tumor has not spread - from where it first started. The main classes of tumors are:

  • Renal cell carcinomas (RCC). These are the most common malignant kidney tumors. They are found in main substance of the kidney, where the filtering occurs. RCC may form as a single tumor within a kidney or as two or more tumors in one kidney.
  • Benign kidney tumors. About 20% of tumors removed from kidneys are benign. There are about nine named tumors in this class. Some can grow quite large but they are almost always non-cancerous and do not spread to other organs.
  • Wilms tumors. Wilms tumors almost always occur in children and are rarely found in adults.

Basic Facts about Kidney Cancer

Kidney cancer is one of the top 10 most common cancers in the United States, with more than 76,000 new cases diagnosed each year. More men than women are diagnosed with kidney cancer.  Kidney cancer can be seen in anyone but is more common in African Americans, American Indians and Alaskan Native people. You can get kidney cancer at any age but it is more common in older people (those greater than 75 years old). The earlier kidney cancer is diagnosed—the better your chances of survival. 

What Causes Kidney Masses?

There is no known cause for developing a kidney mass. But there are a number of things that can increase your risk for kidney tumors such as:

    • Smoking
    • Obesity, poor diet
    • High blood pressure
    • Being on kidney dialysis
    • Workplace exposure to chlorinated chemicals
    • Heredity, which accounts for about 4-6% of kidney cancer cases

What are the Symptoms of a Kidney Mass?

Most kidney masses have no symptoms in the early stages. If there are symptoms, they will most likely be:

    • Hematuria (blood in urine)
    • Flank pain between the ribs and hips
    • Low back pain on one side (not caused by injury) that does not go away
    • Loss of appetite
    • Weight loss not caused by dieting
    • Fever that is not caused by an infection and does not go away
    • Anemia (low red blood cell count)


Most kidney masses have no symptoms in the early stages. If there are symptoms, they will most likely be:

  • Hematuria (blood in urine)
  • Flank pain between the ribs and hips
  • Low back pain on one side (not caused by injury) that does not go away
  • Loss of appetite
  • Weight loss not caused by dieting
  • Fever that is not caused by an infection and does not go away
  • Anemia (low red blood cell count)


Over half of kidney masses are found by chance. Often they are found during generic screening or when you see a doctor about some other problem. If your doctor thinks you may have kidney problems, they might send you to a urologist. A urologist is a doctor who specializes in the urinary system.

There are no routine laboratory tests to find kidney masses. Your health care provider may use many tests to help learn more about your kidneys. Here are some tests and procedures you might expect:

  • Physical exam and history
  • Basic or complete metabolic panel (CMP) to check organ function
  • Complete blood count (CBC) to check the blood for signs of disease
  • Urinalysis to check for infection, blood and protein in urine
  • Serum creatinine levels or other kidney function tests to check if the kidneys are getting rid of waste
  • Ultrasound to get images of your kidneys
  • CT scan and MRI to help diagnose and stage kidney masses
  • Bone scan and chest x-ray to find out if the cancer has spread
  • Kidney mass biopsy to help find out what type of tumor you have

Grading and Staging

A tumor grade tells how aggressive the cancer cells are in your body. A tumor stage tells how much the cancer has spread. Grades 1 through 4 show increasing severity with “1” being the lowest level and “4” the highest. A higher grade and more advanced stage usually come with larger tumor size and more aggressive tumors. Tumor size helps in assessing risk for cancer developing.

Kidney cancer is staged using the tumor node metastases (TNM) system.

The “T” in the TNM system tells us the size of the main (primary) tumor and whether it has grown into nearby areas.

  • T1: Tumor 7.0 cm (about 2 .8 inches) or less, confined to the kidney
  • T1a: Tumor 4.0 cm (about 1 .6 inches) or less, confined to the kidney
  • T1b: Tumor 4.0-7.0 cm, confined to the kidney
  • T2: Tumor greater than 7.0 cm, confined to kidney
  • T2a: Tumor greater than 7.0 cm and less than 10 .0 cm, confined to the kidney
  • T2b: Tumor greater than 10 cm (about 3 .9 inches), confined to the kidney
  • T3: Tumor grows into major veins but not into the adrenal gland and not beyond Gerota’s fascia
  • T4: Tumor reaches beyond Gerota’s fascia (including the adrenal gland). This is not a localized tumor.

The “N” in the TNM system tells us how much the tumor has spread to nearby (regional) lymph nodes.

  • N0: No regional lymph node metastasis
  • N1: Metastasis in regional lymph node(s)

The “M” in the TNM system tells us about metastasis and whether the cancer has spread (metastasized) to other parts of the body.  Spread is most common to the lungs, bones, liver, brain, and far off lymph nodes.

  • M0: No distant metastasis
  • M1: Distant metastasis

Stage I and II tumors include cancers of any size that are confined to the kidney.

Stage III tumors are either locally invasive (T3) or involve lymph nodes (N1).

Stage IV tumors have spread beyond the kidney into organs nearby (T4) or distant metastases (M1).


The main goals in treating kidney masses is to cure you of the cancer and to protect kidney function where possible.  Protecting kidney function is especially important for patients with only one kidney or some other kidney disease.

For some patients, surgery will never be needed. For others, surgery may be the best choice. In some instances, you may be advised to have a biopsy of the tumor to learn more about its potential aggressiveness.  Then your doctor may recommend one of four treatment choices. These are:

  • Active surveillance
  • Ablation
  • Partial nephrectomy
  • Radical nephrectomy

Active Surveillance

For active surveillance, your doctor will see you at intervals for tests and imaging (taking pictures of inside your body). Active surveillance is considered for small masses less than 3 cm (about 1 .2 inches) in size. The goal is to prevent progression and avoid potential risks and negative effects of other treatments. Your visits will be every three, six or twelvemonths as necessary. You may also have chest x-rays, as well as CT scans and ultrasounds. How often you see your doctor will depend on tumor size and stage and your age and general medical condition.


If your tumor is small (T1a, mass less than three cm in size), your surgeon may consider ablation. Ablation destroys the tumor with extreme heat or cold. Your doctor may do a biopsy before ablation so a pathologist can look closely at the tumor cells to see if there is cancer.

  • Cryoablation (cold ablation) is when very cold gases are passed through a probe to destroy the tumor cells.
  • Radiofrequency ablation (hot ablation) is when a thin, needle-like probe is placed through the skin to reach the tumor. An electric current is passed through the tip of the probe to heat the tumor and destroy the cells.

Partial Nephrectomy

Nephrectomy means removal of the kidney. Partial nephrectomy means the doctor removes the tumor and the diseased part of the kidney but leaves the healthy part. If your tumor is at T1a stage (4cm or less), your doctor may suggest a partial nephrectomy.  A partial nephrectomy can also be done for larger tumors if the tumor appears confined and amenable to this surgical approach.

Radical Nephrectomy

During a radical nephrectomy, the whole kidney is removed. This is done if your kidney tumor shows signs of becoming cancerous or is very large or aggressive. Your body can function well with one good kidney if the other is removed.

Surgery for both types of nephrectomy can often be done via laparoscopic surgery but may need to be done by traditional open surgery depending on the size and characteristics of the tumor. During laparoscopy, your surgeon makes a very small hole in your abdomen and threads a thin, lighted tube to the site to look at the kidney.

Care Management

Your health care team is likely to have several different medical professionals such as a radiologist, urologist, nephrologists, pathologist and medical oncologist. These specialists will work with you to consider all your choices and discuss the risks and benefits of treatment. Genetic counseling might also be recommended if you have a family history of kidney tumors.

Have an open and frank talk with your health care team about your treatment choices.

After Treatment

It is of great value to stay in touch with your health care provider and keep follow-up appointments. These check-ups are important to watch for re-growth of tumors. After initial treatment, your doctor may perform many of the same tests used to diagnose the kidney mass.

A healthy lifestyle can be of value. If you use tobacco now, try to stop. Try to limit your alcohol intake and to eat a balanced diet. Exercise and try to keep your weight within recommended limits.

More Information

Questions to Ask Your Doctor

  • Do I have kidney cancer?
  • What is the stage and grade of my cancer and what does that mean?
  • Has the mass spread anywhere else?
  • What are my treatment choices?
  • Which treatment should I choose, and why?
  • Will I have a lot of pain?  How will my pain be managed?
  • Will I be cured after treatment?
  • What are the chances that the mass will return after treatment?
  • What risks or side effects should I expect from treatment?
  • What can I do to keep my kidneys more healthy?
  • What should I do to get myself ready for treatment?
  • What will we do if the treatment does not work?
  • Can you recommend another urologist for a second opinion?
  • What more can I do to protect my health?
  • How often will I need to have checkups after treatment?
  • How long will I need to stay in the hospital?
  • Following surgery, will I need additional treatments?

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