How is kidney cancer diagnosed ?
Clinical examination
In cases where kidney cancer is suspected, the doctor, often a urologist, will perform a clinical examination to check for a mass in the flank. Since kidney cancer can spread to nearby organs, the liver and lymph nodes will also be examined.
Imaging and biological examinations
Various imaging tests will be prescribed by the urologist: an ultrasound can diagnose kidney cancer, but tumors smaller than 3 cm may sometimes be missed by the radiologist. Therefore, the radiologist's experience is crucial for detecting small tumors.
A CT scan, also known as Computed Tomography (CT), may also be performed. This examination requires the injection of an iodine-based contrast agent. It helps detect kidney cancers about 1 cm in size and contributes to assessing the extent of the disease.
An MRI (Magnetic Resonance Imaging) may sometimes be requested, particularly in cases of kidney failure or severe iodine intolerance.
Various biological tests will also be performed from a blood sample to evaluate kidney function and, in cases of metastasis, liver function.
Biopsy and histological analysis
Sometimes, a percutaneous biopsy may be necessary to clarify the diagnosis. This biopsy involves taking a small sample of the tumor under local anesthesia with a needle, so that the sample can be examined microscopically by a pathologist, a doctor specialized in analyzing organs, tissues, and cells (histological analysis).
This biopsy is particularly recommended when the histological diagnosis could affect the therapeutic management of kidney cancer. It will determine the exact nature of the cancer cells (histological type).
Among renal cell carcinomas, the most common histological type is clear cell carcinoma (75%), which primarily affects men between 40 and 50 years old. Papillary renal cell carcinoma is less common (10-15%) and mainly affects men between 60 and 70 years old.
Chromophobe carcinoma is rarer (5%) and more frequently affects women. Bellini’s carcinoma is very rare (1%) and often more aggressive.
Histological analysis will also allow the pathologist to determine the tumor grade, which ranges from 1 to 3 or 4. The higher the grade, the more the appearance of the cancer cells deviates from that of normal cells, and the more aggressive the cancer cells are.
Extent assessment
The diagnosis of kidney cancer should be followed by a disease extent assessment.
This has been partly achieved through the CT scan and/or MRI but may be supplemented by other imaging tests such as Positron Emission Tomography (PET scan) combined with CT or a bone scan. This assessment will help determine the stage of the disease.
💡 DID YOU KNOW ?
Determining the stage of cancer is primarily of therapeutic importance, as understanding the stage helps to establish the most appropriate treatment for the patient.
It also helps predict the most likely progression of the disease. The stage of cancer is determined based on three criteria.
The first criterion is related to the characteristics of the tumor (T). The second criterion is based on the number of affected lymph nodes (N for Node); the third criterion concerns the presence of metastases and the number of organs involved by these metastases (M). These three criteria are used to define the cancer stage and classify cancers according to the internationally recognized TNM classification system .
Stage 1 cancers are tumors localized in the kidney and smaller than 7 cm.
Stage 2 cancers are tumors localized in the kidney and larger than 7 cm.
In Stage 3 cancers, the tumor may invade the fat surrounding the kidney, the adrenal gland, or the renal vein or vena cava.
For Stage 4 tumors, the cancer has spread to form metastases in tissues adjacent to the kidney, in the lymph nodes, or in other parts of the body.
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Article updated on Dec 26, 2024
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