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 become quite large without causing any pain or other problems.
- Because the kidneys are deep inside the body, small kidney tumors cannot be seen or felt during a physical exam.
- There are no recommended screening tests for kidney cancer in people who are not at increased 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 quite large.
While tests like ultrasound, CT scans, and MRI can sometimes find small tumors, these tests cost a lot and 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.
It is important to tell your doctor if members of your family have had kidney cancer or other problems linked to kidney 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 is important to tell your doctor if 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.
Before having these tests, 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
While early kidney cancers do not usually cause any signs or symptoms, larger ones might. Possible signs and 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
- Weight loss, if you are not trying to lose weight
- Fever that doesn't go away after a few weeks and that is not from an infection
- Anemia (low red blood cell counts)
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 may be done to get a sense of a person’s overall health and to help tell if cancer has spread to other areas. Before surgery, they can help tell if a person is healthy enough to have an operation.
This is likely to be one of the first tests done if the doctor thinks you may 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 to look for cancer cells (called urine cytology).
The complete blood count (CBC) is a test that measures the different cells in the blood, such as the red blood cells, the white blood cells, and the platelets. The test results are often not normal in people with kidney cancer. Blood counts are important to make sure a person is healthy enough for surgery. Other blood tests may be done, too.
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 whether treatment is working
In many cases, imaging tests are able to be 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 need to be done.
CT scan (computed tomography)
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.
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. CT scans take longer than regular x-rays and you might feel a bit confined by the ring while the pictures are being taken.
Before any pictures are taken, you may be asked to drink 1 to 2 pints of a liquid called oral contrast. This helps outline the intestine so that certain areas are not confused with tumors. You may also get an IV (intravenous) line through which a different kind of contrast dye is put in. This helps better outline structures in your body. Some people are allergic to the IV contrast and get hives. Rarely, more serious reactions like trouble breathing or low blood pressure can happen. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays.
IV contrast can damage the kidneys. This happens more often in patients whose kidneys are not working well in the first place. Because of this, your kidney function will be checked with a blood test before you get the contrast.
A CT scan is one of the most useful tests for finding and looking at a tumor inside your kidney. It is also useful in seeing whether cancer has spread to other parts of the body. The CT scan will give precise information about the size, shape, and place of a tumor. It can also help find swollen lymph nodes that might contain cancer.
MRI (magnetic resonance imaging) scan
MRI scans use strong magnets and radio waves instead of x-rays to take pictures. MRI scans take longer than x-rays, often up to an hour. Also, you have to be placed inside a narrow, tube-like machine, which upsets some people. Special, more open MRI machines can sometimes help with this if needed. 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 or they don’t have good kidney function.
Ultrasound uses sound waves to make pictures of your insides. 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. Ultrasound can help find out whether a kidney mass is solid or filled with fluid. If a kidney biopsy is needed, ultrasound can be used to guide a needle into the mass to take a sample.
PET scan (positron emission tomography)
PET scans involve putting a slightly radioactive form of sugar into the bloodstream. The sugar travels throughout the body. Cancer cells take in large amounts of the sugar and a special camera is then used to find these deposits and turn them into pictures. This test is useful to see if the cancer has spread to lymph nodes. PET scans can also be used when the doctor thinks the cancer has spread but doesn’t know where. Some machines are able to do both a PET and CT scan at the same time. But PET and PET/CT scans are not a standard part of the work-up for kidney cancers.
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. X-rays taken 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 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 for some patients to remove the tumor. Angiography can be done as a part of the CT or MRI scan instead of as a separate 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. This is very unlikely unless the cancer is very advanced.
A bone scan can help show if a cancer has spread to your bones. 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 tumors. A surgeon can usually tell from imaging tests if an operation is needed. But a biopsy may be done if other tests have not shown for sure that there is a cancer.
There are 2 types of biopsy: fine needle and core needle. During the fine needle aspiration (FNA), a thin (fine) needle is placed through the skin and guided by CT or ultrasound into the area of concern. Then fluid or small pieces of tissue are removed from the kidney or from another place where the cancer may have spread.
The needle used in core biopsies is larger than that used in FNA. A small cylinder of tissue (about 1/16- to 1/8-inch in diameter and ½-inch long) is removed. In either type of biopsy, the sample is checked under the microscope to see if cancer cells are present.
For either type of biopsy, the skin where the needle is to be put in is first numbed with local anesthesia.
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. A grade 4 would have cancer cells that look very different from normal cells and the outlook for the patient would be worse.
Last Medical Review: 11/27/2012
Last Revised: 04/01/2014