Most kidney cancers are found when people have an ultrasound or scan for an unrelated reason. If your doctor suspects kidney cancer, you may have some of the following tests, but you are unlikely to need them all.
You will probably have urine and blood tests to see how well your kidneys are working and to check for changes that could be caused by kidney cancer, but these tests cannot provide a definite diagnosis. The main tests for diagnosing kidney cancer are imaging scans (see below) and tissue sampling (biopsy). Sometimes the doctor will also recommend an internal examination of the bladder, ureters and kidneys.
It may take up to a week to receive your test results. If you feel anxious while waiting for test results, try talking to a close friend or relative, or call Cancer Council 13 11 20 for support.
Early and advanced kidney cancer
Some kidney cancers are diagnosed when they have already spread beyond the kidney (advanced kidney cancer). This may be because the primary cancer never caused obvious symptoms. The tests discussed in this section are used for diagnosing both early and advanced kidney cancer. The treatments are covered in separate sections. See early kidney cancer or advanced kidney cancer.
You will usually have at least one of the following imaging scans.
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 encounter something dense, like an organ or tumour. An ultrasound is painless and takes about 15–20 minutes.
A CT (computerised tomography) scan uses x-rays 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 identify any tumours in the kidneys, provide information about tumour size, shape and position, and may show whether cancer has spread to other organs and tissues. The scan also helps identify enlarged lymph nodes that might contain cancer. Lymph nodes are small glands found in many parts of the body. If cancer is going to spread, it often spreads first to nearby lymph nodes.
Before the scan, you may have an injection of a dye (called contrast) into one of your veins to help make the scan pictures clearer. This dye travels through your bloodstream to the kidneys, ureters, bladder and other organs. It might make you feel flushed and hot for a few minutes. This side effect should ease quickly, but tell the medical team if you feel unwell. The contrast should be used only if your kidneys are functioning well, so this will have been checked during earlier blood tests. If you are concerned about having the dye, check with the doctor that it is safe to have the dye injection with your level of kidney function.
For the scan, you will need to lie still on a table that moves in and out of the CT scanner, which is a large, doughnut-shaped machine. The whole procedure takes about 30–45 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 are diabetic, have kidney disease or are pregnant.
An MRI (magnetic resonance imaging) scan uses a powerful magnet and radio waves to build up detailed, crosssectional 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 the cancer has spread to the renal vein or spinal cord.
Let your medical team know if you have a pacemaker, as the magnet 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 are concerned about having the dye.
During the scan, you will lie on an examination table inside a large metal tube that is open at both ends. The noisy, narrow machine makes some people feel anxious or claustrophobic. If you think you may become distressed, mention it beforehand to your medical team. You may be given a medicine to help you relax, and you will usually be offered headphones or earplugs. The MRI scan may take between 30 and 90 minutes.
Radioisotope bone scan
A radioisotope scan is used to see if any cancer cells have spread to the bones. It may also be called a nuclear medicine bone scan or simply a bone scan. You might have this test if other scans show you have a very large tumour or advanced kidney cancer. The scan is also used to check how the cancer is responding to the treatment.
A very small amount of radioactive substance is injected into a vein, usually in your arm. You will need to wait while the substance moves through your bloodstream to your bones, which can take about 3–4 hours. 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. However, tell your doctor if you are pregnant, as it may not be safe for you to have this type of scan.
The amount of radioactive substance used for this bone scan is small and disappears from your body through your urine within a few hours. After the scan, you should drink plenty of fluids and avoid contact with young children and pregnant women for the rest of the day. Your treatment team will discuss these precautions with you.
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 and ureters, but they may not be needed if an ultrasound and CT scan have already shown there is a tumour on your kidney.
Removing a tissue sample from the kidney for examination under a microscope is the only way to confirm a diagnosis of kidney cancer. This is known as a biopsy. The procedure used to check for kidney cancer is called a core needle biopsy.
You will have a local anaesthetic to numb the area, and then an interventional radiologist will insert 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 examine the sample under a microscope to see if there have been any changes in the cells.
You may not need a core needle biopsy if the doctor already knows enough from other tests, such as a CT scan, to immediately recommend surgery to remove the tumour. In this case, rather than testing a tissue sample, the removed tumour is tested to confirm that it is cancer.
Surgery without a biopsy first is most likely to be recommended if the tumour is large, looks irregular on the scan, or has obviously spread to the renal vein, adrenal gland or nearby lymph nodes.
In some cases, a tumour on your kidney will turn out to be benign (not cancer). If it is confined to the kidney and is smaller in size, a biopsy of the tumour can allow doctors to make a diagnosis. Benign kidney growths, including oncocytoma and angiomyolipoma, can cause problems, and treatment may be similar to early kidney cancer.
A biopsy may also be done if your doctor suspects that the cancer has spread, and the plan is to treat it with ablation techniques, targeted therapy or immunotherapy, rather than surgery. The biopsy results will help your doctors identify suitable drug therapies.
Grading kidney cancer
By examining a tissue sample taken during a biopsy or surgery, doctors can see how similar the cancer cells look to normal cells and estimate how fast the cancer would grow without any treatment. This is called grading. It helps them decide what follow-up treatment you might need and whether to consider a clinical trial.
There are different systems for grading kidney cancer. The Fuhrman system has been widely used in Australia, but a newer system called the International Society of Urological Pathology (ISUP) system has been introduced. Both systems grade kidney cancer from 1 to 4, with grade 1 being the slowest growing and grade 4 the fastest growing.
Staging kidney cancer
The stage of a cancer describes how large it is, where it is, and whether it has spread in the body. Knowing the stage of the kidney cancer helps doctors plan the best treatment for you. The stage can be given before surgery (clinical staging), but may be revised after surgery (pathologic staging).
If you have kidney cancer, your doctor will use the results of the tests described above to assign a stage of I–IV (see below for more detail):
- stages I–II are considered early kidney cancer
- stages III–IV are considered advanced kidney cancer.
Prognosis means the expected outcome of a disease. It is not possible for anyone to predict the exact course of the disease, but your medical team can give you an idea about common issues that affect people with kidney cancer.
The stage of the cancer is the main factor in determining prognosis. In most cases, the earlier that kidney cancer is diagnosed, the better the chance of successful treatment. If the cancer is found after it has spread to other parts of the body, it is very unlikely that all of the cancer can be removed, but treatment can often keep it under control.
People who can have surgery to remove the cancer tend to have better outcomes. However, other factors such as your age, general fitness and medical history also affect prognosis.
How kidney cancer is staged
In Australia, the TNM system is the method most often used for staging kidney cancer. The TNM gives numbers to the size of the tumour (T1–4), whether or not lymph nodes are affected (N0 or N1), and whether the cancer has spread or metastasised (M0 or M1). Based on the TNM numbers, the doctor then works out the cancer's overall stage (I–IV).
The cancer is confined to the kidney and measures less than 7 cm.
The cancer is larger than 7 cm, may have spread to the renal vein or the outer tissue of the kidney but no further, and has not spread to any lymph nodes.
The cancer is any size and has spread to nearby lymph nodes, or the cancer has spread to the adrenal gland.
The cancer has spread beyond the kidney, adrenal gland and nearby lymph nodes, and is found in more distant parts of the body, such as the abdomen, distant lymph nodes, or organs such as the liver, lungs, bone or brain. Stage IV may also be called metastatic kidney cancer.
Key points about diagnosing kidney cancer
What it is
The main type of kidney cancer is renal cell carcinoma (RCC). Types of RCC include clear cell, papillary and chromophobe.
How is it found
Kidney cancer is most often discovered during a test or scan for an unrelated reason. Because kidney cancer often doesn't produce any symptoms, it may be present for some time before it is found. This means some kidney cancers are diagnosed at an advanced stage.
The main tests to diagnose kidney cancer are:
- imaging scans (ultrasound, CT, MRI and/or bone scans) to show the location of the cancer and whether it has spread
- a core needle biopsy to take a tissue sample from the kidney.
Other tests can give more information about the cancer. These tests may include urine and blood tests to see how well your kidneys are working and to look for changes caused by cancer.
Key information about the cancer
- The grade indicates how fast the cancer is likely to grow. The higher the grade, the faster the cancer cells are growing.
- The stage shows how far the cancer has spread throughout the body. Early kidney cancer is stages I and II, while advanced kidney cancer is stages III and IV.
Expert content reviewers:
A/Prof Declan Murphy, Urologist and Director of Genitourinary Oncology, Peter MacCallum Cancer Centre, VIC; Dr Carole Harris, Medical Oncologist, St George and Sutherland Hospitals, and Clinical Lecturer, The University of New South Wales, NSW; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; A/Prof Shankar Siva, Radiation Oncologist, Peter MacCallum Cancer Centre, VIC; Beth Stone, Consumer.