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How is kidney cancer diagnosed?

Most kidney cancers are found by chance (incidentally) when a person has an ultrasound or another imaging scan for an unrelated reason. If your doctor suspects kidney cancer, you may have some of the tests below, but you are unlikely to need them all.

You will probably have urine and blood tests to check your general health and look for signs of a problem in the kidneys. These tests do not diagnose kidney cancer. They may include:

  • a complete count of the three types of blood cells: red blood cells, white blood cells and platelets
  • tests to check how your kidneys are working
  • blood chemistry tests to measure certain chemicals – high levels of the enzyme alkaline phosphatase could be a sign that kidney cancer has spread to the bones.

You will usually have at least one of the following imaging scans.

Ultrasound – In an ultrasound, soundwaves are used to produce pictures of your internal organs. These might show if there is a tumour in your kidney. For this scan, you will lie down and a gel will be spread over your abdomen or back. A small device called a transducer is passed over the area. The transducer sends out soundwaves that echo when they meet something dense, like an organ or tumour. An ultrasound is painless and takes about 15–20 minutes.

CT scan – A CT (computerised tomography) scan uses x-ray beams to take many pictures of the inside of your body and then a computer compiles them into one detailed, cross-sectional picture.

If kidney cancer is suspected on an ultrasound, your doctor will usually recommend a CT scan. This will help find any tumours in the kidneys, and provide information about the size, shape and position of a tumour. The scan also helps check if a cancer has spread to nearby lymph nodes or to other organs and tissues.

CT scans are usually done at a hospital or radiology clinic. You may be asked to fast (not eat or drink) for several hours before the scan to make the pictures clearer and easier to read. Before the scan, a dye may be injected into a vein in your arm. This dye, known as contrast, helps make the pictures clearer. It travels through your bloodstream to the kidneys, ureters, bladder and other organs. The dye might make you feel flushed and hot for a few minutes and you could feel like you need to pass urine. These effects won’t last long.

For the scan, you will lie flat on a table that moves in and out of the CT scanner, which is large and shaped like a doughnut. This painless test takes about 30–40 minutes.

MRI scan – An MRI (magnetic resonance imaging) scan uses a powerful magnet and radio waves to create detailed, cross-sectional pictures of the inside of your body. Only a few people with kidney cancer need an MRI, but it might be used to check whether cancer has spread from the kidney to the renal vein or spinal cord.

Let your medical team know if you have a pacemaker, as the magnet in an MRI scanner can interfere with some pacemakers. As with a CT scan, a dye might be injected into your veins before an MRI scan. An MRI without dye may be used instead of a CT scan if you have pre-existing kidney problems and cannot have the dye.

During the scan, you will lie on an examination table that slides into a large metal tube that is open at both ends. Lying within the noisy, narrow machine makes some people feel anxious or claustrophobic. If you think you may become distressed, mention this beforehand to your medical team. You may be given a mild sedative to help you relax, and you will usually be offered headphones or earplugs. The MRI scan may take between 30 and 90 minutes.

Before having scans, tell the doctor if you have any allergies or have had a reaction to contrast during previous scans. You should also let them know if you have diabetes or other kidney disease or are pregnant.

Radioisotope bone scan – Also called a nuclear medicine bone scan or simply a bone scan, a radioisotope scan can look for changes in the bones. It’s used only if you have bone pain or blood tests results show high levels of alkaline phosphatase. These may be a sign that the cancer has spread to the bones. If cancer is found in the bones, the scan can also used be used to check how the cancer is responding to treatment.

A radioisotope bone scan uses a very small amount of a radioactive solution. Before you have the scan, the solution is injected into a vein, usually in your arm. You will need to wait for a few hours while the solution moves through your bloodstream to your bones. Your body will be scanned with a machine that detects radioactivity. A larger amount of radioactivity will show up in any areas of bone affected by cancer cells.

Radioisotope bone scans generally do not cause any side effects. After the scan, you need to drink plenty of fluids to help remove the radioactive substance from your body through your urine. You should avoid contact with young children and pregnant women for the rest of the day. Your treatment team will discuss these precautions with you.

PET scan – A PET (positron emission tomography) scan is a specialised imaging test. It uses an injection of a small amount of radioactive solution to help cancer cells show up brighter on the scan. A PET scan is useful for some cancers, but kidney cancer does not always show up well on a standard PET scan. Newer solutions are currently being studied and a PET scan may be used to look for kidney cancer in the future.

Cystoscopy – If you have blood in your urine, your doctor might use a thin tube with a light and camera to look inside your bladder (cystoscopy), ureters (ureteroscopy) and kidneys (ureterorenoscopy). These procedures rule out urothelial carcinoma of the bladder, kidney or ureters, but they
may not be needed if an ultrasound and CT scan have already shown there is a tumour on your kidney.

A biopsy involves removing a tissue sample for examination under a microscope. It is a common way to diagnose cancer, but it is not often needed for kidney cancer before treatment. This is because imaging scans are good at showing if a kidney tumour is cancer.

For many people with kidney cancer, the main treatment is surgery. In this case, the tumour removed during surgery is tested to confirm that it is cancer. A biopsy may be done before treatment when:

  • surgery is not an option because the tumour is very small and active surveillance is suggested – a biopsy will help work out what other treatment is needed
  • the tumour is large, looks irregular on the scan, or has obviously spread to the renal vein, adrenal gland or nearby lymph nodes.

If a biopsy is done, it will be a core needle biopsy. For this procedure, you will have a local anaesthetic to numb the area, and then an interventional radiologist will put a hollow needle through the skin. They will use an ultrasound or CT scan to guide the needle to the kidney and remove a sample of tissue. The procedure usually takes about 30 minutes.

The tissue sample will be sent to a laboratory, and a specialist doctor called a pathologist will look at the sample under a microscope to check for any cell changes.

In some cases, a kidney tumour will turn out to be benign (not cancer). Benign kidney growths, including oncocytoma and angiomyolipoma, can cause problems, and treatment may be similar to the treatment for early kidney cancer.

This information is reviewed by

This information was last reviewed November 2020 by the following expert content reviewers: A/Prof Daniel Moon, Urologic Surgeon, Australian Urology Associates, and Honorary Clinical Associate Professor, The University of Melbourne, VIC; Polly Baldwin, 13 11 20 Consultant, Cancer Council SA; Ian Basey, Consumer; Gregory Bock, Urology Cancer Nurse Coordinator, WA Cancer and Palliative Care Network, North Metropolitan Health Service, WA; Tina Forshaw, Advanced Practice Nurse Urology, Canberra Health Services, ACT; Dr Suki Gill, Radiation Oncologist, Sir Charles Gairdner Hospital, WA; Karen Walsh, Nurse Practitioner, Urology Services, St Vincents Private Hospital Northside, QLD; Dr Alison Zhang, Medical Oncologist, Chris O’Brien Lifehouse and Macquarie University Hospital, NSW.