TNM system for bladder cancer
The American Joint Committee on Cancer (AJCC) developed the TNM system to evaluate three primary factors when it comes to treating cancer:
- Tumor (T) describes the size of the original tumor, including whether it has grown through the bladder wall or invaded nearby tissues.
- Node (N) indicates whether the cancer is present in the lymph nodes.
- Metastasis (M) indicates whether the cancer has spread (metastasized) to other parts of the body.
A number (0-4) or the letter X is assigned to each factor. A higher number indicates increasing severity. For instance, a T1 score indicates a smaller tumor than a T2 score. The letter X means the information could not be assessed.
Once the T, N and M scores have been assigned, an overall bladder cancer stage is assigned.
T categories for bladder cancer:
These measurements refer to the primary tumor.
- TX: primary tumor cannot be assessed; information not known
- TO: no evidence of primary tumor
- Ta: noninvasive papillary carcinoma
- Tis:noninvasive flat carcinoma, also called flat carcinoma in situ. This means that the disease is still localized, or contained within the urothelium layer of the bladder wall. Cancer cells have not invaded the deeper layers of bladder wall tissue.
- T1: the tumor has grown from the layer of cells lining the bladder into the connective tissue below. It has not grown into the muscle layer of the bladder.
- T2: tumor has grown into the muscle layer
- T2a: the tumor is in the inner half of the muscle layer
- T2b: the tumor is in the outer half of the muscle layer
- T3: tumor has grown through the muscle layer and into the surrounding fatty tissue
- T3a: this spread into the fatty tissue can only be seen with a microscope
- T3b: this spread into the fatty tissue is large enough to be seen on imaging test or to be seen/felt by the surgeon
- T4: tumor has spread into nearby organs or structures. It may be growing in the stroma (main tissue) of the prostate, the seminal vesicles, uterus, vagina, pelvic wall or abdominal wall
N categories for bladder cancer:
- NX: nearby lymph nodes cannot be assessed; information not known
- N0: the cancer has not spread to any nearby lymph nodes
- N1: the cancer has spread to one lymph node in the true pelvis
- N2: the cancer has spread to two or more lymph nodes in the true pelvis
- N3: the cancer has spread to lymph nodes that lie along the common iliac artery
M categories for bladder cavity and oropharyngeal cancers:
- M0: no distant spread
- M1: the cancer has spread to distant sites outside the bladder region (for example, the lungs, liver or bones)