Learn The BasicsThe stage of bladder cancer describes its size and whether or not it has spread, while the grade describes how abnormal the cells look under the microscope.
Stages of bladder cancer
There are two different methods of determining the stage of bladder cancer. These are the TNM staging system and the number staging system.
TNM
TNM stands for Tumor, Nodes, Metastasis. ‘T’ describes the extent of the primary tumor growth through the bladder wall and whether it has reached tissues that are nearby and is divided into six stages: Tis, Ta, T1, T2, T3 and T4.
In Tis, also known as the carcinoma in situ (CIS) stage, flat high-grade cancer cells are limited to the bladder lining. Ta tumors are papillary growths limited to the lining of the bladder. In T1 bladder cancer, the cancer has started to grow into the connective tissue beneath the bladder lining. T2 means that it has grown through the connective tissue into the muscle, T3 means that it has grown through the muscle into the fat layer, and T4 means the cancer has spread outside the bladder.
The ‘N’ category describes whether the cancer has spread to the lymph nodes and is also divided into 4 stages from N0 to N3.
N0 means that there are no cancer cells in any lymph nodes, N1 means that there are cancer cells in one lymph node in the pelvis, N2 means that there are cancer cells in more than one lymph node in the pelvis and N3 means that there are cancer cells in one or more lymph nodes outside of the pelvis.
‘M’ describes the spread of the cancer to different parts of the body and is divided into 2 stages as M0 and M1( a or b).
M0 means that the cancer has not spread to other parts of the body. M1a means that it has spread to the lymph nodes outside the pelvis and M1b means that it has spread to other parts of the body, like the bones, lungs and liver.
Number staging system
According to the number staging system, bladder cancer is divided into 5 stages from stage 0 to stage 4.
In stage 0, the cancer is situated just in the inner layer of the bladder lining or there are very early, high-grade cancer cells only in the inner layer of the bladder lining.
In stage 1, the cancer has started to grow into the connective tissue underneath the bladder lining.
In stage 2, it has grown through the connective tissue layer into the muscle of the bladder wall.
In stage 3, it has grown through the muscle into the fat layer and may have spread to the prostate, uterus or vagina. It may also have spread to nearby lymph nodes.
Finally, in stage 4, the cancer has spread to the abdominal wall or between the pelvis, distant lymph nodes or to other parts of the body like the bones, lungs or liver.
Grades of bladder cancer
Bladder cancer is divided into three grades.
In grade 1, cancer cells look very similar to normal cells. They are called low-grade or well-differentiated and they tend to grow slowly and generally stay in the lining of the bladder.
In grade 2 bladder cancer, the cancer cells look less like normal cells. They are called moderately differentiated and are more likely to spread into the muscle layer of the bladder. Grade 2 bladder cancer is also more likely to recur after treatment.
Finally, in grade 3 bladder cancer, the cancer cells look very abnormal. They are called high-grade or poorly differentiated and grow more quickly. They are also more likely to spread into the muscle layer of the bladder and recur following treatment.
Bladder cancer can also be described as either low- or high-grade. High-grade bladder cancer is more likely to grow, spread and recur.
Bladder cancer types for treatment purposes
Bladder cancer can also be divided into two groups for treatment purposes depending on how invasive the cancer may be. These are non-muscle-invasive and muscle-invasive bladder cancer.
Non-muscle invasive bladder cancer is bladder cancer that has not grown into the wall of the bladder to reach the muscle tissue, while muscle-invasive bladder cancer is bladder cancer that has grown into the muscle tissue or deeper and needs to be treated with more extensive therapies.