Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer’s stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancer.
One tool that doctors use to describe the stage is the TNM system. This system uses three criteria to judge the stage of the cancer: the tumor itself, the lymph nodes around the tumor, and if the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:
- How large is the primary tumor and where is it located? (Tumor, T)
- Has the tumor spread to the lymph nodes? (Node, N)
- Has the cancer metastasized to other parts of the body? (Metastasis, M)
Tumor. Using the TNM system, the "T" plus a letter and/or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. If there is more than one tumor, the lowercase letter "m" (multiple) is added to the "T" stage category. Specific tumor stage information is listed below.
TX: The primary tumor cannot be evaluated due to a lack of information.
T0: There is no evidence of a primary tumor in the bladder.
Ta: This refers to noninvasive papillary carcinoma. Cancer cells are grouped together and can often be easily removed.
Tis: This stage is carcinoma (cancer) in situ, or "flat tumor." This means that the cancer is only found in cells within the lining of the bladder. The doctor may also call it noninvasive/superficial bladder cancer or noninvasive flat carcinoma (the cancer is on or near the surface of the bladder). This type of bladder cancer often comes back after treatment, usually as another noninvasive cancer in the bladder.
T1: The tumor has spread to the subepithelial connective tissue (the tissue below the membrane or covering of the bladder).
T2: The tumor has spread to the muscle.
T2a: The tumor has spread to the inner half of the muscle (which may be called the superficial muscle.)
T2b: The tumor has invaded the deep muscle of the bladder (the outer half of the muscle).
T3: The tumor has grown into the perivesical tissue (the fatty tissue that surrounds the bladder).
T3a: The tumor has grown into the perivesical tissue, as seen through a microscope.
T3b: The tumor has grown into the perivesical tissue macroscopically, meaning that the tumor (s) is large enough to be seen during imaging tests or to be seen or felt by the doctor.
T4: The tumor has spread to any of the following: the abdominal wall, the pelvic wall, a man’s prostate, or a woman’s uterus or vagina.
T4a: The tumor has spread to the prostate, uterus, or vagina.
T4b: The tumor has spread to the pelvic wall or the abdominal wall.
Node. The “N” in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes near the bladder, within the true pelvis (called hypogastric, obturator, iliac, perivesical, pelvic, sacral, and presacral nodes), are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.
NX: The regional lymph nodes cannot be evaluated due to a lack of information.
N0: The cancer has not spread to the regional lymph nodes.
N1: The cancer has spread to a single lymph node, with the size of its largest area being 2 centimeters (cm) or smaller.
N2: The cancer has spread to a single lymph node, with a size greater than 2 cm but no more than 5 cm in its largest area. Or, the cancer has spread into more than one lymph node, with the size of each metastasis being 5 cm or smaller at its largest point.
N3: The cancer has spread to at least one lymph node that measures more than 5 cm at its largest point.
Distant metastasis. The "M" in the TNM system indicates whether the cancer has spread to other parts of the body.
MX: Distant metastasis cannot be evaluated.
M0: The disease has not metastasized.
M1: There is distant metastasis.
Grading
Tumor grade. In addition to the TNM system, the cancer may also be evaluated and assigned a grade (G). Doctors use the term grade to describe how much the tumor tissue appears like normal bladder tissue. The grade of a cancer can give the doctor an idea of how quickly the cancer may grow and spread. It is determined by looking at the tumor cells under a microscope. Normal bladder tissue usually has different types of cells grouped together, called differentiated tissue. Cancerous bladder tissue is made up of cells that look more similar to each other. This is less differentiated tissue and looks less like normal bladder tissue. In general, the more differentiated the bladder cancer tissue, the better the prognosis.
GX: The tumor grade cannot be identified.
G1: The cells look more like normal bladder tissue cells (well differentiated).
G2: The cells are somewhat different (moderately differentiated).
G3: The cells are unlike normal bladder tissue cells (poorly differentiated)
G4: The tumor cells do not resemble normal cells (undifferentiated).
Recently, some doctors have tried to simplify the grading system by making the categories more distinct, and replacing four grades with three:
G1: Well-differentiated
G2: Moderately differentiated
G3: Poorly differentiated/undifferentiated
The World Health Organization (WHO) recommends changing bladder cancer grading to only two categories (well-differentiated and poorly differentiated), but this new grading system is not yet widely used.
Cancer stage grouping
Doctors assign the stage of the bladder cancer by combining the T, N, and M classifications.
Stage 0a: This is an early cancer that is only found on the surface of the inner (inside) lining of the bladder. Cancer cells are grouped together and can often be easily removed. The cancer has not invaded the muscle or connective tissue of the bladder wall. This type of bladder cancer is also called noninvasive papillary urothelial carcinoma (Ta, N0, M0).
Stage 0is: This stage of cancer, also known as flat or carcinoma in situ, is found only on the inner lining of the bladder. It has not grown in toward the hollow part of the bladder, and it has not spread to the thick layer of muscle or connective tissue of the bladder. This is always a high-grade cancer (see above) (Tis, N0, M0).
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Stage I: The cancer has grown through the inner lining of the bladder to the lamina propria. It has not spread to the thick layer of muscle in the bladder wall. It has not spread to the lymph nodes or any other organs (T1, N0, M0).
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Stage II: The cancer has spread into the thick muscle wall of the bladder (also called invasive cancer). It has not reached the fatty tissue surrounding the bladder and has not spread to the lymph nodes or other organs (T2, N0, M0).
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Stage III: The cancer has spread throughout the muscle wall to the fatty layer of tissue surrounding the bladder. It may also have spread to the prostate (in men) or the uterus and vagina (in women). It has not spread to the lymph nodes or other organs (T3 or T4a, N0, M0).
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Stage IV: The tumor has spread through the bladder wall into the walls of the abdomen or pelvis, and/or it has spread to nearby lymph nodes. It may also be found in parts of the body far away from the bladder, such as the bones, liver, or lungs (any T, any N, M1).
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Recurrent cancer: Recurrent cancer is cancer that comes back after treatment. It may come back where is first began or in another part of the body.
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Sixth Edition (2002) published by Springer-Verlag New York, www.springer-ny.com.
Last Updated: January 27, 2009
