How is kidney cancer found?
Many kidney cancers are found fairly early, while they are still only in the kidney. But others are found at a more advanced stage. There are a few reasons why kidney cancer may not be found early:
- The cancer can grow quite large without causing any pain or other problems.
- Because the kidneys are deep inside the body, small kidney tumors can’t be seen or felt during a physical exam.
- There are no good screening tests to look for kidney cancer in people who are not at increased risk.
Some tests can find some kidney cancers early, but none of these is recommended for screening in people at average risk.
Small amounts of blood in the urine could point to kidney cancer. But there are many other causes of blood in the urine, including infections and kidney stones. And some people with kidney cancer don’t have blood in their urine until the cancer is advanced.
Tests like ultrasound, CT scans, and MRI can sometimes find small kidney tumors, but these tests often can’t show whether a tumor is cancer. They are only recommended to screen for kidney cancer in those people who have a high risk of getting the disease. Often kidney cancer is found “incidentally,” meaning that the cancer is found by accident during tests for some other illness. The survival rate for kidney cancer found this way is very high because the cancer is usually found at a very early stage.
Genetic tests for inherited conditions linked to kidney cancer
It’s important to tell your doctor if any family members (blood relatives) have or had kidney cancer, especially at a younger age, or if they have an inherited condition linked to this cancer, like von Hippel-Lindau disease. Your doctor may suggest that you think about genetic testing to see if you have the condition.
Before being tested, it’s important to talk with a genetic counselor so that you understand what the tests can − and can’t − tell you, and what any results would mean. The tests are used to find these conditions, not kidney cancer itself. Your risk may be increased if you have one of these conditions, but it does not mean that you have or will get kidney cancer. To learn more about genetic testing, see our document Genetic Testing: What You Need to Know.
Signs and symptoms of kidney cancer
Early kidney cancers do not usually cause any signs or symptoms, but larger ones might. Possible symptoms of kidney cancer include:
- Blood in the urine
- Low back pain on one side (not from an injury)
- A mass or lump on the side or lower back
- Feeling tired
- Weight loss, if you are not trying to lose weight
- Fever that is not from an infection and that doesn’t go away
Talk to a doctor if you notice any of these problems. They are often caused by other, benign conditions, but only a doctor can tell for sure. The doctor can take your medical history and do a physical exam. Then, if there is any reason to suspect kidney cancer, one or more tests may be done.
Lab tests can’t show for sure if a person has kidney cancer, but they can sometimes give the first hint that there may be a kidney problem. If cancer has been found, lab tests can be done to get a sense of a person’s overall health and to help tell if cancer has spread to other areas.
This is likely to be one of the first tests done if the doctor thinks you might have a kidney problem. Urine tests look for blood and other substances in a urine sample. Sometimes the urine will be looked at under the microscope for cancer cells (called urine cytology).
Complete blood count (CBC): This test measures the different cells in the blood, such as the red blood cells, the white blood cells, and the platelets. People with kidney cancer often have too few red blood cells (called anemia).
Blood counts are important to make sure a person is healthy enough for surgery.
Blood chemistry tests: These tests can show how well the kidneys and some other organs are working.
Imaging tests are used to make pictures of the inside of your body. These tests may be done to:
- Help find out whether a certain area might be cancer
- Learn how far cancer may have spread
- Find out if treatment is working
- Look for signs of the cancer coming back
In many cases, imaging tests can show whether a tumor in the kidney is cancer, but in some cases a biopsy (taking out a piece of the tumor to be looked at under a microscope) may be needed to be sure.
CT (computed tomography) scan
A CT (or CAT scan) is a special type of x-ray in which many pictures are taken from different angles and then combined by a computer to give detailed pictures of the inside of the body.
This is one of the most useful tests for finding and looking at a tumor in your kidney. It can show the size, shape, and position of a tumor. It can also show if a cancer has spread to other parts of the body. If a kidney biopsy is needed, a CT scan can be used to guide a needle into the mass to take a sample.
A CT scanner has been described as a large donut, with a narrow table in the “hole.” You will need to lie still on the table while the scan is being done.
Before any pictures are taken, you may be asked to drink a liquid called oral contrast. You may also get an IV (intravenous) line through which a different kind of contrast dye is put in. Some people are allergic to the contrast. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays.
MRI (magnetic resonance imaging) scan
MRI scans use strong magnets and radio waves instead of x-rays to make detailed pictures. MRI scans are used less often than CT scans in people with kidney cancer. They may be done in cases where a person can’t have the CT contrast dye, such as when they have an allergy to it.
MRI scans take longer than CT scans, often up to an hour. Also, you have to lie inside a narrow, tube-like machine, which upsets some people. Special, more open MRI machines can sometimes help with this if needed.
Ultrasound uses sound waves to make pictures of your insides. This test can help show whether a kidney mass is solid or filled with fluid (kidney cancers are more likely to be solid). If a kidney biopsy is needed, ultrasound can be used to guide a needle into the mass to take a sample.
For this test, a wand is moved over the skin after a gel is applied. It gives off sound waves and picks up the echoes as they bounce back. This test is painless and does not use radiation.
PET (positron emission tomography) scan
PET scans can be useful to see if the cancer has spread to lymph nodes. They can also be used when the doctor thinks the cancer has spread but doesn’t know where. But PET scans are not a standard part of the work-up for kidney cancers.
For this test, a slightly radioactive form of sugar is put into the bloodstream. Cancer cells take in large amounts of the sugar. A special camera is then used to find these deposits and turn them into pictures.
Some machines can do both a PET and CT scan at the same time.
Intravenous pyelogram (IVP)
An IVP is an x-ray of the kidney taken after a special dye is put into a vein. This dye travels from the blood into the kidneys and then passes into the ureters and bladder. The dye shows up on x-rays, which can help find a cancer or show damage caused by the tumor. But this test is not often used when kidney cancer is suspected.
Like the IVP, this x-ray test uses a contrast dye. A small thin tube called a catheter is usually threaded up a large artery in your leg and into the artery leading to your kidney (the renal artery). It can help outline the blood vessels feeding a kidney tumor, which in turn helps doctors plan surgery to remove the tumor.
Angiography is often done as a part of the CT or MRI scan instead of as a separate x-ray test.
A chest x-ray can show if the cancer has spread to the lungs. The lungs are a common site of kidney cancer spread, but this is very unlikely unless the cancer is advanced.
A bone scan can help show if a cancer has spread to your bones. PET scans can often show the spread of cancer to bones as well, so if you’ve had a PET scan you might not need a bone scan.
For this test, a slightly radioactive substance is put into a vein. It travels to the bones, where it can be seen by a special camera. By itself, a bone scan can’t show the difference between cancer and problems like arthritis, so other tests may be needed.
Biopsies are not often used to diagnose kidney cancers. A surgeon can usually tell from imaging tests if surgery is needed. But a biopsy may be done if other tests haven’t shown for sure that there is a cancer.
There are 2 types of biopsies. For either type of biopsy, the skin where the biopsy needle is to be put in is numbed first. The needle is then guided into place using CT or ultrasound.
- Fine needle aspiration (FNA): For this biopsy, a thin (fine) needle is placed through the skin. Fluid or small pieces of tissue are then removed.
- Core needle biopsy: The needle used in core biopsies is larger than that used in FNA. A small cylinder of tissue is removed.
For either type of biopsy, the sample is checked under the microscope for cancer cells.
An important feature of kidney cancer is the grade of the cancer. Grade refers to how much the cancer cells look like normal cells under the microscope. Kidney cancers are usually graded on a scale of 1 to 4. The lower the number, the more the cancer cells look like normal cells and the better the outlook for the patient.
Last Medical Review: 04/29/2014
Last Revised: 04/29/2014