How is kidney cancer diagnosed?

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 full blood count to check the levels of red blood cells, white blood cells and platelets
• tests to check how well your kidneys are working
• blood chemistry tests to measure the levels of certain substances in the blood (e.g. high levels of the enzyme alkaline phosphatase could be a sign that kidney cancer has spread to the bones).

Various imaging scans can create pictures of the inside of your body and provide different types of information. You will usually have at least one of the following imaging scans.

Ultrasound

An ultrasound uses soundwaves to create pictures of your internal organs. These might show if there is a tumour in your kidney. During an ultrasound, you will lie on a bench and uncover your abdomen (belly) or back. A cool gel will be spread on your skin, and a small handheld device called a transducer will be moved across the area. The transducer creates soundwaves that echo when they meet something solid, such as an organ or tumour. A computer turns the soundwaves into a picture. An ultrasound scan is painless and usually takes 15–20 minutes.

CT scan 

A CT (computerised tomography) scan uses x-ray beams and a computer to create a detailed picture of the inside of the body. 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.

During the scan, you will need to lie still on a table that moves in and out of the scanner, which is large and round 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. Most people with kidney cancer won’t 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 or any other metallic object in your body. If you do, you may not be able to have an MRI scan, although some newer devices are safe to go into the scanner. Before the MRI, you may be injected with a dye to help make the pictures clearer. 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 takes between 30 and 90 minutes.

Radioisotope bone scan

Also called a nuclear medicine bone scan or simply a bone scan, this scan can show if kidney cancer has spread to your bones. It’s used only if you have bone pain or if blood tests show high levels of alkaline phosphatase. If cancer is found in the bones, the scan can also be used to check how the cancer is responding to treatment.

Before the scan, a tiny amount of a radioactive substance is injected into a vein. The substance collects in areas of abnormal bone growth. You will need to wait for a few hours while it moves through your bloodstream to your bones. Your body will be scanned with a machine that detects radiation.  A larger amount of the substance will usually show up in any areas of bone with 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 after your scan. 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, so most people don’t need one.

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 or breastfeeding.

Looking inside your bladder, ureters or kidneys

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) or kidneys (pyeloscopy).

You will have an anaesthetic before these procedures. This will usually be a local anaesthetic for a cystoscopy and a general anaesthetic before a ureteroscopy or pyeloscopy.

For a few days after these tests you may see some blood in your urine and feel mild discomfort when urinating. These procedures help rule out urothelial carcinoma, which can start in the bladder, a ureter or part of the kidney. They may not be needed if imaging scans have found a kidney tumour.

See our information on Bladder Cancer and Upper Tract Urothelial Cancer if those cancers are diagnosed.

A biopsy is when doctors remove a sample of cells or tissue from an area of the body. It is a common way to diagnose cancer, but it is not always  needed for kidney cancer before treatment. For many people with kidney cancer, the main treatment is surgery. In this case, the tissue removed during surgery is tested to confirm that it is cancer.

A biopsy may be done before treatment when:

• it is uncertain if the tumour is cancerous or benign
• alternative treatments (such as ablative therapy, active surveillance or radiation therapy) are recommended – a biopsy will help work out what other treatment is needed
• it appears that the cancer has spread beyond the kidney and a biopsy will be helpful to guide systemic drug therapy.

If a biopsy is done, it will be a core needle biopsy. 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 but you may need to rest for a few hours before you can go home. You may also have some discomfort or notice some blood in your urine.

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). Small benign kidney growths, including oncocytoma and angiomyolipoma,  may not need treatment. If they do, it may be similar to the treatment for early kidney cancer.