How Renal Cell Carcinoma Is Diagnosed

Roughly half of the renal cell carcinoma cases are now discovered incidentally, in imaging scans for other conditions before symptoms develop.

If renal cell carcinoma is suspected, diagnosis usually begins with a physical examination and lab work that may reveal blood in the urine and other signs. Imaging studies and a biopsy will also be done to confirm the diagnosis and help guide treatment.

This article will explain the diagnostic process for renal cell carcinoma as well as how the cancer is staged.

Doctors discussing a CT scan

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Self-Checks/Screening

There are currently no self-checks, at-home tests, or routine screening tests that are helpful in the diagnosis of renal cell carcinoma.

That said, roughly 4% of cases are attributed to hereditary conditions. So, it's important to take the time to learn about your family's medical history and get tested for genetic syndromes. This allows you and your healthcare team to set up screening, and it increases the likelihood of early detection and treatment.

Physical Examination

If you develop symptoms that are suggestive of this type of cancer (such as blood in the urine or unintentional weight loss), your healthcare provider will first ask about your symptoms and take your medical history and your family's medical history.

Your healthcare provider may ask about any risk factors you have (such as smoking, high blood pressure, or chronic use of anti-inflammatory pain medications), and if any of your relatives have had the disease.

Your healthcare provider will also do a thorough physical exam, looking for any masses (lumps) in the abdomen. Uncommonly, an enlarged vein in the left scrotum (varicocele) may occur if the tumor obstructs a vein going to the kidney or leg swelling may result if the tumor obstructs the large vein returning blood to the heart.

Incidental Discovery

Over 50% of renal cell carcinoma tumors are now diagnosed before they cause any symptoms. They usually are detected as part of an imaging test done for another reason.

Labs and Tests

Several different lab tests may be ordered if your doctor suspects renal cell carcinoma. These include:

  • Urinalysis: A test to look for the presence of blood in the urine (hematuria) under a microscope is often the first test that is ordered.
  • Complete blood count: White blood cell count is commonly elevated with renal cell carcinoma. For those who have paraneoplastic syndromes (rare disorders in which a cancerous tumor triggers an abnormal immune response), elevated red blood cell count (polycythemia) may be seen.
  • Additional blood tests: Your healthcare team may order additional blood tests to check your general health, such as a blood calcium test, liver function test, and kidney function tests. Kidney function tests are particularly important both for the diagnosis and also to determine if any precautions need to be taken during imaging tests (such as the use of contrast dye).

Imaging

Depending on the results of a physical examination and lab tests, imaging tests are often performed as the next step. Options include:

Computerized tomography (CT) scan: A CT scan combines multiple X-rays of a region from different angles to create a 3-dimensional image. Contrast refers to a dye that is injected into a vein that travels to a region to be imaged to further define the image. A contrast-enhanced CT scan is the preferred first test for evaluating either a mass in the kidney or hematuria that persists.

This test can identify roughly 90% of renal cell carcinomas. It can also give your healthcare team some idea about the extent of a mass. for instance, it can identify whether cancer extends beyond the kidney or appears to have spread to lymph nodes in the region.

Magnetic resonance imaging (MRI): An MRI may be recommended as an alternative to CT for some people, such as children, to avoid exposure to radiation. In an MRI, a magnetic field and radio waves are used to create a 3-dimensional image of the inside of the body. MRI may be able to reveal more information than a CT about how far the tumor has advanced locally or whether there are blood clots in veins to the kidneys.

Ultrasound: An ultrasound is sometimes the first test done to discover a renal cell carcinoma. This test may sometimes be done after the above tests to determine the extent to which the tumor has involved the veins going to the kidneys (renal vein) or the large vein returning blood from the lower half of the body to the heart (inferior vena cava).

Biopsy

Before treatment is started, a biopsy is usually done to confirm the suspected diagnosis. This is a surgical procedure in which a sample of the tumor is removed and sent to a lab to be studied under a microscope.

A core needle biopsy is performed most often. In this procedure, a long, thin needle is inserted through the skin to the location of the tumor to remove a sample. This procedure is usually done with localized anesthesia (medication to numb the area where the needle is inserted). You may be given some medication to help you relax.

What Biopsy Results Show

In a lab, a pathologist (a specialist in diagnosing diseases) will study the tissue sample to confirm whether cells are cancerous and determine the subtype and grade of the tumor. Subtypes include:

  • Clear cell (most common)
  • Papillary
  • Chromophobe
  • Collecting or Bellini duct tumors (uncommon, accounting for fewer than 1% of these cancers)

Tumor grade is a measure of the aggressiveness of the cancer. A tumor grade of 1 is least aggressive, and a tumor grade of 4 is most aggressive.

In addition to evaluating the tumor sample under the microscope, further studies may also be done to guide treatment. For example, tests may be needed to identify whether a tumor may be more likely to respond to some types of immunotherapy (immune checkpoint inhibitors).


Staging

TNM System

Renal cell carcinoma tumors are evaluated using something called the "TNM" system. In this system, "T" stands for the tumor and has different numbers depending on the size of the tumor, "N" stands for lymph nodes, and "M"stands for metastases.

  • "T" is for tumor: The number following the "T" indicates the size and location of the tumor. T1 tumors haven't spread and are less than 7 centimeters (cm) in diameter. T2 tumors have not spread, and is larger than 7 cm in diameter. T3 tumors have grown into tissues near the kidney or have spread into a major vein (such as the renal vein or inferior vena cava). A T4 tumor has spread to an area beyond Gerota's fascia (a capsule that surrounds the kidneys and adrenal glands) or into the adrenal gland on the same side of the body.
  • "N" is for (lymph) nodes: The numbers here are based on whether the cancer has spread to lymph nodes. N0 means the cancer has not spread to lymph nodes. N1 means the cancer has spread to regional lymph nodes.
  • "M" is for metastases: A tumor that is M0 has no evidence of distant spread, whereas a tumor that is M1 has spread to distant organs or tissues. Common areas where kidney cancer may spread include the bones, liver, lungs, brain, and distant lymph nodes.

Using the TMN system, renal cell carcinoma is then broken into five stages:

Stage 0

Renal cell carcinoma is rarely discovered at stage 0. At this stage it is referred to as carcinoma in situ or a precancerous lesion and has not spread beyond something called the basement membrane. A tumor that is stage 0 is considered noninvasive, and should theoretically be 100% curable with removal.

Stage 1

In stage 1 renal cell carcinoma, the tumor is 7 cm in diameter or smaller and has not spread beyond the kidney. TNM stage: T1, N0, M0.

Stage 2

A renal cell carcinoma that is in stage 2 is larger than 7 cm, but like stage 1, it has not spread beyond the kidney. TNM stage: T2, N0, M0.

Stage 3

There are two different situations in which a renal cell carcinoma might be stage 3:

  • A tumor is any size and has spread to regional lymph nodes but not to any distant tissues or organs; TNM stage: T1 or T2, N1, M0
  • The tumor has spread into tissues surrounding the kidney (perinephric tissue) or major veins (renal vein or inferior vena cava) and may have spread to regional lymph nodes but not to distant regions of the body; TNM stage: T3, any N, M0

Stage 4

There are two situations that may result in renal cell carcinoma being stage 4:

  • A tumor is any size and may or may not have spread to lymph nodes but has spread to a distant organ such as the lungs, bones, or the brain; TNM stage: any T, any N, M1
  • A tumor has spread beyond something called Gerota's fascia and extends into the adrenal gland (on the same side of the body). It may or may not have spread to lymph nodes and has not spread to distant organs; TNM stage: T4, any N, M0

Recurrent

A renal cell carcinoma may also be classified as recurrent if it was undetectable after treatment and comes back later on. With recurrent tumors, the stage after recurrence will depend on whether the tumor comes back in the kidney (local recurrence), shows up in areas near the kidney or lymph nodes (regional recurrence), or surfaces in distant organs (distant recurrence).

Differential Diagnosis

There are a number of conditions that may cause similar symptoms to renal cell carcinoma or a mass in the kidney on imaging. In addition, renal cell carcinoma may cause a number of symptoms not directly related to the kidneys, which has led it to be coined one of the great mimickers in medicine.

Some of the conditions doctors consider in the differential diagnosis of renal cell carcinoma include:

  • Kidney cysts or polycystic kidney disease: Cysts in the kidneys are very common, occurring in 10% of people overall and in 20% of people over the age of 50.
  • Benign kidney tumors: Tumors such as renal adenomas angiomyolipomas or benign oncocytoma may cause a kidney mass that may or may not resemble renal cell carcinoma.
  • Metastases to the kidneys: The spread of other cancers to the kidneys is uncommon but can occur. By far, the most common is lung cancer (almost half of kidney metastases).
  • Other cancerous tumors that arise in the kidneys: Other types of kidney cancer such as transitional cell cancers are often found more centrally in the kidneys.
  • Other kidney conditions: Some other conditions may initially resemble renal cell carcinoma, including renal infarcts (death of kidney tissue to lack of blood supply), hydronephrosis (swelling of the kidneys due to the buildup of urine), or kidney abscess (a collection of pus in the kidneys)

Summary

More than 50% of renal cell carcinomas are found incidentally through imaging tests for other conditions.

If renal cell carcinoma is suspected based on symptoms, your healthcare provider will first take your medical history and your family's health history and do a physical exam. You will also have blood and urine tests. Finally, you may undergo imaging studies, including a CT scan, MRI, or ultrasound, and have a biopsy taken. The biopsy will help your healthcare team determine the subtype, grade, and stage of your cancer, which will help in determine the right course of treatment.

A Word From Verywell

While half of renal cell carcinomas are now found incidentally, before symptoms are present, it's important to be aware of the diagnostic process. This type of cancer is considered one of the great mimickers in medicine, and symptoms may suggest conditions unrelated to the kidney. For this reason, healthcare providers are taught to have a "high index of suspicion."

That said, it can be very worrisome to go through the process of getting diagnosed. However, there is plenty you can do to be your own advocate. Having a primary care physician who is familiar with your medical and family history is a good start. It's also wise to share any symptoms you've been experiencing, no matter how trivial they may seem to you. As with a puzzle, every piece of information is important in diagnosing this cancer, and any cancer, as early as possible.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."