Your kidneys lie deep in the body so cancer cannot be found during a routine physical examination. As with all cancers, early detection can improve success rates and increase treatment options. Your doctor may use different approaches to diagnose kidney cancer, depending on the symptoms you display.
All approaches begin with a careful physical examination, combined with a complete discussion of past and present medical problems. Because kidney cancer may spread to other parts of your body, it is important to be very thorough in testing for its presence. Your doctor may order some or all of a variety of tests to determine the extent of your cancer and to develop your treatment plan. The most common tests that may be ordered include:
Urinalysis or urine test: the most common symptom and sign of a kidney tumour is blood in the urine. This test can also detect other irregularities in the urine such as protein and cancer cells. Urinalysis is usually part of a complete physical exam. Microscopic and chemical tests are performed that will detect small amounts of blood and other substances not seen with the naked eye. About half of all patients with kidney cancer will have blood in their urine. Microscopic examination of urine samples (called urine cytology) can also detect cancer cells in the urine.
Blood tests: a thin needle is used to take a small piece of tissue from the cancer cells. The tissue is then examined under a microscope. This is the best way to confirm the type of cancer cells. A complete blood count and chemical test of the blood can detect findings associated with kidney cancer. Anaemia (too few red blood cells) is very common. Erythrocytosis (too many red blood cells) may also occur because some of these kidney cancers produce a hormone (erythropoietin) that can increase red blood cell production by the bone marrow. High levels of liver function enzymes in the blood (for reasons not known) and hypercalcemia (high calcium levels) sometimes occur.
Ultrasound: this scan uses sound waves to detect if a kidney irregularity is a fluid-filled cyst or a tumour. If there is blood in the urine, an ultrasound of the abdomen with special attention to the kidneys, ureters, and bladder may be ordered. Usually no preparation is needed for this test, and it is generally not uncomfortable. It utilizes sound waves to produce images of internal organs, helping the radiologist detect any masses that may be present. A wand called a transducer is passed over the skin, and emits sound waves that are detected as echoes bouncing back off internal organs. The echo-pattern images produced by kidney tumours look different from those of normal kidney tissue. This test may be used for initial diagnosis of a kidney mass or to help visualize a mass when a fine needle biopsy is done (see Biopsy Procedure).
Chest X-ray: a plain X-ray of organs and bones within the chest may be done to see if the cancer has spread to the lungs. If something is seen on the X-ray, the doctor may order a Computed Tomography (CT) scan of the chest to help determine what it is.
Computed Tomography (CT scan): a modified x-ray that takes pictures of the body at different angles then combines them to produce a detailed cross-section of the body. A CT scan is a highly specialized x-ray that is used to visualize internal organs and provides a very accurate cross section picture of specific areas of the body. It is used as one of the primary imaging tools for the assessment of kidney cancer. If the initial sign of the tumour is a mass or thickening in the kidney area detected on an x-ray taken for other reasons, or seen or felt from the outside of the body, a CT scan is often ordered. CT scans are more detailed than ordinary x-rays, taking pictures of your organs one thin slice at a time from different angles. Then a computer puts the images together to show the size and location of any abnormalities. To enhance the image of the abdominal organs, dye may be taken orally (by mouth) before the scan. An intravenous (IV) may also be placed for injection of additional contrast dye. There is generally no pain associated with the CT scan, although the IV dye may cause a hot flushing sensation. Some people may also experience an allergic reaction to IV dye (also called IV contrast), especially individuals who are allergic to iodine. Depending on the part of the body visualized, dietary restrictions may be required prior to the procedure.
Magnetic resonance imaging (MRI): another way of making cross-sectional images of the body using magnets and radio waves. An MRI is a highly specialized scan that is similar to a CT scan, but may be better suited for assessing certain areas of the body, such as the bones. It creates an accurate cross-section picture of specific organs within the body, to allow for a layer-by-layer examination. An MRI is usually not a painful procedure. Because it uses a powerful magnet to produce the images, people with metal within their body – such as prosthetic hip replacements, pacemakers, or metal plates- should discuss the use of an MRI with their physician and the MRI technician before the scan is performed. The test may require the patient to lie still for a long time usually in a narrow space, which may be difficult for some people who do not like closed in spaces. MRI scans are often used in cases where CT scans may not be able to view an area of the body well enough.
Angiography: this procedure is used to visualize location and function of arteries. A catheter is usually threaded up a large artery in the leg into an artery leading to your kidney (renal artery). A contrast dye is then injected into the artery to outline blood vessels. Angiography can outline the blood vessels that supply a kidney tumour, which can help a surgeon better plan an operation. Angiography may also help diagnose kidney cancers since the blood vessels supplying tumours usually look different than the normal blood supply to the kidney.
Positron Emission Tomography (PET) scan: a very specialized diagnostic study that provides information about how extensively a cancer has spread based on certain activities of the cells. PET scans are typically used for breast, colorectal, ovarian, lymphoma, lung, melanoma, and head & neck cancer. The effectiveness of PET scans for kidney cancer is still being studied. Unlike CT and MRI scans, which produce images of internal organs or other structures, a PET scan produces images based on the chemical and physiological changes related to a cell’s metabolism. This is important because chemical and physiological changes in the cells often occur before structural changes in tissues can be seen. The result is that PET scans can help distinguish benign from malignant tumours and help doctors determine the stage of cancer spread in the patient. PET scans can also measure whether or not treatment therapies are working. PET scans are quite often used in combination with CT and MRI scans.
Cytoscopy: a test that checks the bladder and urethra for cancers. A telescope with a lens and a light is placed into the bladder through the urethra.
Bone scan: a small amount of radioactive material is injected into a vein and travels through the bloodstream to the bones so the scanner can detect the tumour. A bone scan is used to check for the spread of cancer to the bones. It is done by injecting small amounts of a special radioactive material through a vein into your bloodstream. This material is carried to the bone, where it collects in areas where there is a lot of bone activity. The test can identify both cancerous and non-cancerous diseases but the test can’t distinguish between cancer and other conditions such as arthritis when used it is used alone. Therefore other tests may be needed, such as x-rays or CT scans.
Biopsy procedure: if, after diagnostic tests are complete, there is a strong clinical suspicion that the kidney mass is cancerous (malignant), surgical removal of the kidney (nephrectomy) will be performed without delay. If the diagnostic test results are not clear, a biopsy may be performed. During a biopsy procedure a small sample of tissue is removed from the mass and examined to determine whether it is benign or malignant.
There are several ways to perform a biopsy of a kidney mass, though the most common method is a procedure called a fine needle aspiration or fine needle biopsy. Using ultrasound or a CT scanner for guidance, the doctor will insert a long thin needle through the skin, directly into the mass, and remove the sample tissue. This is generally not an uncomfortable procedure.
A pathologist will then evaluate the biopsy tissue under a microscope to determine whether it is benign or malignant. If it is malignant, the pathologist also will identify the histology, or cell type. If there is clear evidence of widespread metastasis at the time of the discovery of the kidney mass, a biopsy may be taken from an area of metastasis, instead of from the kidney. This may be recommended to reduce risk of bleeding, if the metastatic area is more easily accessible than the kidney.
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