Introduction to Bladder Cancer

Staging of Bladder Cancer

Staging is the method used by doctors to evaluate how far the cancer has spread once it has been discovered. Staging plays an important role in determining both the treatment options as well as predicting the prognosis (chances of recovery).

The TNM classification system is used most frequently for staging patients with bladder cancer. The TNM staging system provides vital information about the following important aspects of the disease:

• T = Tumor - The "T" designation refers to the extent of invasion of the tumor into the bladder wall and nearby tissue and organs. The extent of tumor invasion is scored on a numerical scale ranging from 1 to 4. In general, the higher the "T" score, the greater the extent of invasion of the tumor into the deeper layers of the bladder wall or nearby tissue.

  • T1 - tumor is confined to the bladder and has invaded the transitional epithelium but has not reached the level of the bladder muscle.

  • T2 - tumor is confined to the bladder but has penetrated into the muscle layer. This stage is further subdivided into two subgroups:

    • T2a - bladder tumor has penetrated the inner layer of muscle
    • T2b - bladder tumor has penetrated the outer layer of muscle

  • T3 - tumor has extended beyond the bladder wall to the perivesical fatty tissue that surrounds the bladder. This stage is further subdivided into two subgroups:

    • T3a - tumor cells can be observed only under a microscope (microscopic tumor)
    • T3b - tumor is visible with the naked eye (macroscopic tumor)

  • T4 - tumor has spread beyond the bladder and has invaded adjacent structures such as the prostate gland, uterus, vagina, abdominal wall, or pelvic wall. This stage is further subdivided into the following 3 subgroups:

    • T4a - bladder tumor invades the prostate gland
    • T4b - bladder tumor invades gynecological structures
    • T4c - bladder tumor invades the wall of the rectum

• N = Lymph Node Involvement - The second aspect of the TNM staging system measures whether or not the cancer has spread to the regional (nearby) lymph nodes and, if so, the size of the lymph nodes. The extent and size of lymph node involvement is scored on a numerical scale ranging from 0 to 3. In general, the higher the "N" score, the greater the extent of lymph node involvement.

  • N0 - the cancer has not spread to any of the regional lymph nodes.

  • N1 - the cancer has spread to only a single lymph node; the size of the lymph node is 2.0 cm or less.

  • N2 - the cancer has spread to either a single lymph node the size of which measures 2.0 to 5.0 cm OR the cancer has spread to more than one lymph node none of which are larger than 5.0 cm.

  • N3 - the cancer has spread to a lymph node the size of which is larger than 5.0 cm.

• M = Metastasis - The last feature that is evaluated by the TNM staging system is whether or not that cancer has metastasized (spread) to distant organs (e.g., lungs, bone, liver) or to lymph nodes that are located far away from the bladder. A score of "M0" indicates no evidence of metastasis while a score of "M1" indicates that the cancer has metastasized to distant organs or lymph nodes.

Once all of the staging information has been obtained, the TNM values are combined to determine the clinical stage of the disease. Patients with bladder cancer are assigned to one of 5 clinical stages:

• Stage 0
• Stage I
• Stage II
• Stage III
• Stage IV

In general, the five stages of bladder cancer reflect the extent of severity of the disease ranging from the earliest stage (Stage 0) to the most advanced stage (Stage IV). As mentioned previously, staging is an important feature of the disease that is used by doctors to determine the most appropriate type of treatment as well as to predict the long-term outcome (prognosis).