Renal cell carcinoma is often detected incidentally: a routine x-ray reveals that the kidney is enlarged. From there, further testing is required to confirm the diagnosis. Once a diagnosis is made, the cancer is staged to determine how advanced the tumor is. The stage assigned to a tumor often includes survival statistics.
Diagnosis usually begins with a physical exam. Your doctor palpates the area around the kidney, checking for signs of unusual growth or firmness. The doctor will ask a number of questions about your medical history, exposure to substances that can cause cancer, and your lifestyle. Blood and urine tests may also be ordered.
If your physical exam leads your doctor to suspect cancer, further testing will be ordered. Diagnostic tools such as an ultrasound or IVP are used to determine the presence and size of a tumor.
An ultrasound uses high frequency sound waves to generate a picture of the kidney. An ultrasound is non-invasive, has few if any side effects, and generates an image that can provide information about the size and density of any suspicious areas of the organ. As such, ultrasound is one of the most common diagnostic tests ordered for renal cell carcinoma.
Intravenous Pyelogram (IVP)
An intravenous pyelogram, or IVP, is also a common choice when diagnosing kidney cancer. The soft tissues of the kidneys, ureters and bladder are often indistinguishable from other abdominal features, so a dye is useful in highlighting these areas as it flows through the kidneys.
The iodine-based dye is injected into the body through a vein. The dye makes its way through the blood, eventually being removed by the kidneys, and passing through the ureters and bladder. The IVP is actually a series of x-rays that constructs a picture of the dye as it passes through these organs. Abnormal growths can then be seen on the x-ray films.
Veins and arteries are normally not visible in an x-ray, so arteriography, like IVP, uses dye to highlight these features on an x-ray. The dye in the arteriography is injected locally using a catheter, allowing a greater concentration of dye and a high resolution image. This is also known as a renal angiogram. Similarly, a renal venogram can be performed by placing the catheter into the renal vein and injecting the dye there.
Computed Tomography (CT Scan)
A computed tomography, or CT scan, offers detailed images of internal organs. A CT scan takes a series of x-rays, each photographing a “slice” of the kidney. These “slices” are combined using a computer to generate a 3-dimensional image of the organ. Because the procedure is so detailed, a CT scan is often used to determine the possible spread of the disease to other organs.
Although diagnostic tools such as ultrasound and IVP can reveal the presence of a tumor, a biopsy is the only way to determine with accuracy whether the growth is malignant or not. A needle is inserted into the tumor, and a sample of the tissue is removed. The sample is then examined microscopically for signs of cancer.
Lung Cancer and Metastasis
Once the diagnosis is confirmed, the stage of the cancer must be determined. To do so, it is necessary to determine whether the cancer has metastasized or spread to other organs. The lungs, adrenal glands, bone, liver and brain are often targets of metastasis. A chest x-ray is used to determine if the lungs are affected.
A bone scan is used to check for metastasis to the bones. During the test, a small amount of radioactive material is injected into the body, where it is absorbed by the bones. Cancerous areas show up on the scan because they accumulate larger concentrations of the radioactive material than healthy bone tissue.
Staging and Survival Rates
Two different staging systems are used to classify RCC: Robson and TNM. The two systems are similar, but TNM staging is increasing in use as it allows for a more detailed description of the disease.
Since the 1980s, five-year survival rates for RCC have increased to almost sixty percent. Staging is perhaps the most important prognostic factor when determining survival rates. Stage I cancer, in which the tumor is confined to the kidney, has a five-year survival rate of ninety percent, for instance. Stage IV, in which the cancer has spread to cause lung cancer or infiltration of other organs, has a five-year survival rate of less than thirty percent.
TNM Staging System
T= Tumor (1-4, describes the size of the mass and the spread)
N = Nodes (0-2, describes spread to local lymph nodes, with 0 being no spread)
M = Metastasis (0 = no metastasis; 1 = distant metastasis)
The combination of T, N, and M are used to determine the stage of the disease (Stage I through IV).
Robson Staging System
Stage I: Limited to the kidney.
Stage II: Spread through the kidney capsule and into the fatty tissue surrounding the kidney and/or the adrenal gland.
Stage III: Spread into neighboring lymph nodes and/or blood vessels.
Stage IV: Spread to nearby organs (other than adrenal glands) or spread through the bloodstream to more distant organs, such as the lungs, liver or bone.