Kidney Cancer: Diagnosis

Approved by the Cancer.Net Editorial Board, 10/2020

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

This section describes options for diagnosing kidney cancer. Not all tests listed below will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose kidney cancer:

  • Blood and urine tests. The doctor may recommend having a blood test to check the number of red blood cells in the blood. A urine test may be recommended to look for blood, bacteria, or cancer cells. These tests may suggest that kidney cancer is present, but they cannot be used to make a definite diagnosis.

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. This is usually performed as an outpatient procedure using local anesthesia by an interventional radiologist. Anesthesia is medicine that blocks the awareness of pain. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. A pathologist then analyzes the sample(s) and writes a pathology report describing the results. This report becomes a permanent part of the person’s medical record.

    The pathology report identifies the type of cell involved in the kidney cancer (see the Introduction for a list), which is important in planning treatment. Metastatic kidney cancer is cancer that has spread beyond the kidney to other parts of the body. Medical oncologists are doctors who treat cancer using medication. A medical oncologist must have a pathology report before they recommend a systemic therapy to treat metastatic kidney cancer. Systemic therapy involves using medication(s) that affect the entire body. In certain cases, surgeons also may request a renal tumor biopsy to assist in planning treatment. However, if imaging tests show a solid and growing mass, then surgeons may remove the tumor first and then the pathologist will later provide the definitive tumor type and stage.

    Since every patient's situation is different, the patient should carefully discuss with their doctor whether a biopsy is needed before treatment.

Imaging tests

  • Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. For patients being evaluated for a renal mass, a non-contrast CT scan is done before a contrast medium is injected. A contrast medium is a special dye that provides better detail on the images taken by CT scans. This dye is injected into a patient’s vein. Renal cysts will not take up the contrast medium, but renal tumors will. A non-contrast CT showing fat in a renal tumor suggests it is a benign angiomyolipoma (see Introduction), and nonsurgical treatment options may be recommended. If patients have severe chronic kidney disease or kidney failure, then the contrast medium cannot be safely used. A CT scan of the urinary tract is called a CT urogram. Note that a PET-CT scan is not useful in renal cell carcinoma because the contrast used in most PET scans is excreted through the kidneys and bladder, which limits the ability to see kidney tumors.

  • X-ray. An x-ray is a way to create a picture of the structures inside of the body, using a small amount of radiation.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can be used to measure the tumor’s size. A special dye called gadolinium is given before the scan to create a clearer picture. This dye is injected into a patient’s vein.

  • Cystoscopy and nephro-ureteroscopy. Occasionally, special tests called a cystoscopy and nephro-ureteroscopy may be done for a urothelial cancer of the upper urinary tract or renal pelvis (see Introduction). They are not often used for renal cell carcinoma unless imaging also finds a mass or stone in the bladder. During these procedures, the patient is sedated, while a tiny, lighted tube is inserted into the bladder through the ureter and up into the kidney. Sedation is giving medication to become more relaxed, calm, or sleepy. This procedure can be used to obtain tumor cells for examination under a microscope, to perform a biopsy, and sometimes to completely destroy small tumors.

After diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging.

The next section in this guide is Stages. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.