After someone is diagnosed with bladder cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes the extent (amount) of cancer in the body. It helps determine how serious the cancer is and how best to treat it. The stage is one of the most important factors in deciding how to treat the cancer and determining how successful treatment might be.
The stage of bladder cancer is based on the results of physical exams, biopsies, and imaging tests (CT or MRI scan, x-rays, etc.), as well as the results of surgery.
Understanding your bladder cancer stage
A staging system is a standard way for the cancer care team to describe how far a cancer has spread. The staging system most often used for bladder cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:
- T describes how far the main (primary) tumor has grown through the bladder wall and whether it has grown into nearby tissues.
- N indicates any cancer spread to lymph nodes near the bladder. Lymph nodes are bean-sized collections of immune system cells, to which cancers often spread first.
- M indicates if the cancer has spread (metastasized) to distant sites, such as other organs, like the lungs or liver, or lymph nodes that are not near the bladder.
Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, usually after surgery, this information is combined in a process called stage grouping to assign an overall stage.
The earliest stage cancers are called stage 0 (or carcinoma in situ), and then range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means a more advanced cancer. And within a stage, an earlier letter means a lower stage. Cancers with similar stages tend to have a similar outlook and are often treated in much the same way.
The staging system in the table below uses the pathologic stage. It’s based on the results of the physical exam, biopsy, imaging tests, and the results of surgery. This is likely to be more accurate than clinical staging, which only takes into account the tests done before surgery. Bladder cancer staging can be complex. If you have any questions about your stage, please ask your doctor to explain it to you in a way you understand. (An explanation of the TNM system follows the stage table.)
T categories for bladder cancer
The T category describes how far the main tumor has grown into the wall of the bladder (or beyond).
The wall of the bladder has 4 main layers.
- The innermost lining is called the urothelium or transitional epithelium.
- Beneath the urothelium is a thin layer of connective tissue, blood vessels, and nerves.
- Next is a thick layer of muscle.
- Outside of this muscle, a layer of fatty connective tissue separates the bladder from other nearby organs.
Nearly all bladder cancers start in the lining or urothelium. As the cancer grows into or through the other layers in the bladder, it becomes more advanced (the stage goes up).
The T categories are described in the table above, except for:
TX: Main tumor cannot be assessed due to lack of information
T0: No evidence of a primary tumor
N categories for bladder cancer
The N category describes spread only to the lymph nodes near the bladder (in the true pelvis) and those along the blood vessel called the common iliac artery. These lymph nodes are called regional lymph nodes. Any other lymph nodes are considered distant lymph nodes. Spread to distant nodes is considered metastasis (described in the M category). Surgery is usually needed to find cancer spread to lymph nodes, since this is seldom seen on imaging tests.
NX: Regional lymph nodes cannot be assessed due to lack of information.
N0: There’s no regional lymph node spread.
N1: It has spread to 1 nearby lymph node in the true pelvis.
N2: It has spread to 2 or more lymph nodes in the true pelvis.
N3: It has spread to lymph nodes along the common iliac arteries.
M categories for bladder cancer
The M categories are describes the spread to a distant sites.
M0: It has not spread to a distant sites
M1a: It has spread to distant lymph nodes.
M1b: It has spread to 1 or more distant organs, such as the bones, liver, or lungs.