How is kidney cancer staged?
Staging is the process of finding out how far a cancer has spread. Your treatment and prognosis (outlook) depend, to a large extent, on the cancer's stage.
Staging is based on the results of the physical exam, biopsies, and imaging tests (CT scan, chest x-ray, PET scan, etc.), which are described in the section, "How is kidney cancer diagnosed?"
There are actually 2 types of staging for kidney cancer. The clinical stage is your doctor's best estimate of the extent of your disease, based on the results of the physical exam, lab tests, and any imaging studies you have had. If you have surgery, your doctors can also determine the pathologic stage, which is based on the same factors as the clinical stage, plus what is found during surgery and examination of the removed tissue. This means that if you have surgery, the stage of your cancer might actually change afterward (if cancer were found to have spread further than was suspected, for example). Pathologic staging is likely to be more accurate than clinical staging, because it allows your doctor to get a firsthand impression of the extent of your disease.
AJCC (TNM) staging system
A staging system is a standardized way in which the cancer care team describes the extent of the cancer. The most commonly used staging system is that of the American Joint Committee on Cancer (AJCC), sometimes also known as the TNM system. The TNM system describes 3 key pieces of information:
- T indicates the size of the main (primary) tumor and whether it has grown into nearby areas.
- N describes the extent of spread to nearby (regional) lymph nodes. Lymph nodes are small bean-shaped collections of immune system cells that are important in fighting infections.
- M indicates whether the cancer has spread (metastasized) to other organs of the body. (The most common sites of spread are to the lungs, bones, liver, and distant lymph nodes.)
Numbers or letters appear after T, N, and M to provide more details about each of these factors. The numbers 0 through 4 indicate increasing severity. The letter X means "cannot be assessed because the information is not available."
T categories for kidney cancer
TX: The primary tumor cannot be assessed (information not available).
T0: No evidence of a primary tumor.
T1: The tumor is only in the kidney and is 7 cm (a little less than 3 inches) or less across
- T1a: The tumor is 4 cm (about 1 1/2inches) across or smaller and is only in the kidney.
- T1b: The tumor is larger than 4 cm but not larger than 7 cm across and is only in the kidney.
T2: The tumor is larger than 7 cm across but is still only in the kidney.
- T2a: The tumor is more than 7 cm but not more than 10 cm (about 4 inches) across and is only in the kidney
- T2b: The tumor is more than 10 cm across and is only in the kidney
T3: The tumor is growing into a major vein or into tissue around the kidney, but it is not growing into the adrenal gland (on top of the kidney) or beyond Gerota's fascia (the fibrous layer that surrounds the kidney and nearby fatty tissue).
- T3a: The tumor is growing into the main vein leading out of the kidney (renal vein) or into fatty tissue around the kidney
- T3b: The tumor is growing into the part of the large vein leading into the heart (vena cava) that is within the abdomen.
- T3c: The tumor has grown into the part of the vena cava that is within the chest or it is growing into the wall of that blood vessel (the vena cava).
T4: The tumor has spread beyond Gerota's fascia (fibrous layer that surrounds the kidney and nearby fatty tissue). The tumor may have grown into the adrenal gland (on top of the kidney).
N categories for kidney cancer
NX: Regional (nearby) lymph nodes cannot be assessed (information not available).
N0: No spread to nearby lymph nodes.
N1: Tumor has spread to nearby lymph nodes.
M categories for kidney cancer
M0: There is no spread to distant lymph nodes or other organs.
M1: Distant metastasis is present; includes spread to distant lymph nodes and/or to other organs. Kidney cancer most often spreads to the lungs, bones, liver, or brain.
Once the T, N, and M categories have been assigned, this information is combined to assign an overall stage of I, II, III, or IV. The stages identify cancers that have a similar prognosis and thus are treated in a similar way. Patients with lower stage numbers tend to have a better prognosis.
Stage I: T1, N0, M0
The tumor is 7 cm across or smaller and is only in the kidney (T1). There is no spread to lymph nodes (N0) or distant organs (M0).
Stage II: T2, N0, M0
The tumor is larger than 7 cm across but is still only in the kidney (T2). There is no spread to lymph nodes (N0) or distant organs (M0).
Stage III: Either of the following:
T3, N0, M0: The tumor is growing into a major vein (like the renal vein or the vena cava) or into tissue around the kidney, but it is not growing into the adrenal gland or beyond Gerota's fascia (T3). There is no spread to lymph nodes (N0) or distant organs (M0).
T1 to T3, N1, M0: The main tumor can be any size and may be outside the kidney, but it has not spread beyond Gerota's fascia. The cancer has spread to nearby lymph nodes (N1) but has not spread to distant lymph nodes or other organs (M0).
Stage IV: Either of the following:
T4, any N, M0: The main tumor is growing beyond Gerota's fascia and may be growing into the adrenal gland on top of the kidney (T4). It may or may not have spread to nearby lymph nodes (any N). It has not spread to distant lymph nodes or other organs (M0).
Any T, Any N, M1: The main tumor can be any size and may have grown outside the kidney (any T). It may or may not have spread to nearby lymph nodes (any N). It has spread to distant lymph nodes and/or other organs (M1).
Other staging and prognostic systems
The TNM staging system is useful, but some doctors have pointed out that there are factors other than the extent of the cancer that should be considered when determining prognosis and treatment.
University of California Los Angeles (UCLA) Integrated Staging System
This is a more complex system that came out in 2001. It was meant to improve upon the AJCC staging that was then in place. Along with the stage of the cancer, it takes into account a person's overall health and the Fuhrman grade of the tumor. These factors are combined to divide people into low-, intermediate-, and high-risk groups. Ask your doctor if he or she uses this system and how it might apply to you. In 2002, researchers at UCLA published a study evaluating their system, looking at survival rates of the low-, intermediate- and high-risk groups. For patients with localized kidney cancer (cancer not spread to distant organs) they found 5-year survival rates of 91% for low-risk groups, 80% for intermediate groups, and 55% for high-risk groups.
Stage of disease is a predictor of survival. Researchers have linked certain factors with shorter survival times in people with kidney cancer that has spread outside the kidney. These include:
- High blood lactate dehydrogenase (LDH) level
- High blood calcium level
- Anemia (low red blood cell count)
- Cancer spread to 2 or more distant sites
- Less than a year from diagnosis to the need for systemic treatment (targeted therapy, immunotherapy, or chemotherapy)
- Poor performance status (a measure of how well a person can do normal daily activities)
People with none of the above factors are considered to have a good prognosis; 1 or 2 factors are considered intermediate prognosis, and 3 or more of these factors are considered to have a poor prognosis (outlook) and may be more or less likely to benefit from certain treatments.
Last Medical Review: 11/08/2012
Last Revised: 01/18/2013