Kidney Cancer: Diagnosis

Approved by the Cancer.Net Editorial Board, 09/2022

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 the cancer has spread, it is called metastasis. 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.

How kidney cancer is diagnosed

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 only way to make a definite diagnosis, even if other tests can suggest that cancer is present. During biopsy, a small amount of tissue is removed 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. A pathologist 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. A medical oncologist must have a pathology report before they recommend a systemic therapy plan using medication to treat kidney cancer, particularly metastatic disease. Metastatic kidney cancer is cancer that has spread beyond the kidney to other parts of the body. Systemic therapy involves using medication(s) that affect the entire body. Medical oncologists are doctors who treat cancer using medications. In certain cases, surgeons also may request a renal tumor biopsy to help plan 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 person's situation is different, they should carefully discuss with their doctor whether a biopsy is needed before treatment.

  • Biomarker testing of the tumor. Your doctor may recommend running laboratory tests on a tumor to identify specific genes, proteins, and other factors unique to the tumor. This may also be called molecular testing of the tumor. Results of these tests can help determine your treatment options.

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 first to evaluate for any non-cancerous types of disorders like a kidney stone or bleeding cyst. Then, contrast medium is injected. 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. In addition the contrast will help look for any involvement of cancer in the nearby blood vessels, lymph nodes, or faraway organs like the liver. 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 positron-emission tomography (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 creates a picture of the structures inside of the body using a small amount of radiation.

  • Magnetic resonance imaging (MRI). An MRI produces detailed images of the inside of the body using magnetic fields, not x-rays. 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. Gadolinium is also taken up by cancers and seen more clearly on the final pictures.

  • Cystoscopy and nephro-ureteroscopy. Occasionally, special tests called a cystoscopy and nephro-ureteroscopy may be done for 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 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.