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 was 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.)

T categories for kidney cancer

TX: The primary tumor cannot be assessed (information not available).

T0: No evidence of a primary tumor.

T1a: The tumor is 4 cm (about 11/2 inches) across or smaller and is limited to the kidney.

T1b: The tumor is larger than 4 cm but not larger than 7 cm (about 2¾ inches) across and is limited to the kidney.

T2: The tumor is larger than 7 cm across but is still limited to the kidney.

T3a: The tumor has spread into the adrenal gland (which sits on top of the kidney) or into fatty tissue around the kidney, but not beyond the fibrous layer that surrounds the kidney and nearby fatty tissue (Gerota's fascia).

T3b: The tumor has spread into the main vein leading out of the kidney (renal vein) and/or the part of the large vein leading into the heart (vena cava) that is within the abdomen.

T3c: The tumor has reached the part of the vena cava that is within the chest or it invades the wall of the vena cava.

T4: The tumor has spread beyond Gerota's fascia (fibrous layer around the kidney and nearby fatty tissue).

NX: Regional (nearby) lymph nodes cannot be assessed (information not available).

N0: No spread to nearby lymph nodes.

N1: Tumor has spread to 1 nearby lymph node.

N2: Tumor has spread to more than 1 nearby lymph node.

MX: Presence of distant metastasis cannot be assessed (information not available).

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 (such as the lungs, bones, 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

T1a-T1b, N0, M0: The tumor is 7 cm across or smaller and limited to the kidney. There is no spread to lymph nodes or distant organs.

Stage II

T2, N0, M0: The tumor is larger than 7 cm across but is still limited to the kidney. There is no spread to lymph nodes or distant organs.

Stage III

Different combinations of T and N categories are included in this stage.

T3a-T3c, N0, M0: The main tumor has reached the adrenal gland, the fatty tissue around the kidney, the renal vein, and/or the large vein (vena cava) leading from the kidney to the heart. It has not spread beyond Gerota's fascia. There is no spread to lymph nodes or distant organs.

T1a-T3c, 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 1 nearby lymph node but has not spread to distant lymph nodes or other organs.

Stage IV

Several combinations of T, N, and M categories are included in this stage.

T4, N0-N1, M0: The main tumor has invaded beyond Gerota's fascia. It has spread to no more than 1 nearby lymph node. It has not spread to distant lymph nodes or other organs.

Any T, N2, M0: The main tumor can be any size and may be outside the kidney. The cancer has spread to more than 1 nearby lymph node but has not spread to distant lymph nodes or other organs.

Any T, Any N, M1: The main tumor can be any size and may be outside the kidney. It may or may not have spread to nearby lymph nodes. It has spread to distant lymph nodes and/or other organs.

Survival rates for kidney cancer by TNM stage

The numbers below come from several different studies published within the past 10 years. There are some important points to note about these numbers:

• The 5-year survival rate refers to the percentage of patients who live at least 5 years after being diagnosed. Many of these patients live much longer than 5 years after diagnosis.
• Although these numbers are among the most current we have available, they represent people who were first diagnosed and treated many years ago. Improvements in treatment since then mean that the survival rates for people now being diagnosed with these cancers may be higher.
• Although survival statistics can sometimes be useful as a general guide, they may not accurately represent any one person's prognosis. A number of other factors, including other tumor characteristics and a person's age and general health, can also affect outlook. Your doctor is likely to be a good source as to whether these numbers may apply to you, as he or she is familiar with the aspects of your particular situation.

Other staging and prognostic systems

While the TNM staging system is useful, 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 but probably more accurate system. Along with the stage of the cancer, it takes into account a person's overall health and the Fuhrman grade of the tumor to divide people into low, intermediate, and high risk groups. You may want to ask your doctor if he or she uses this system and how it might apply to your case. Researchers at UCLA recently 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 97% for low risk groups, 81% for intermediate groups, and 62% for high risk groups.

Survival predictors

Stage of disease is a predictor of survival. Now researchers have linked certain factors with shorter survival times in people with kidney cancer:

• 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)
• low performance status (a measure of how well a person can do normal daily activities)