The TNM Staging System is the most common way in which doctors determine the stage of bladder cancer. The doctor may call non-invasive, invasive or advanced non-muscular bladder cancer.

Tumor (T)– describes the size of the tumor.

• Tis – cancerous cells are very early, high-grade, present only in the innermost layer of the bladder mucosa;
• Ta – cancer is only in the highest layer of the bladder mucosa;
• T1 – cancer has started to develop into connective tissue under the bladder mucosa;
• T2 – cancer has been formed through connective tissue in the muscles;
• T2a – cancer has developed in the superficial muscle;
• T2b – cancer has developed in deeper muscle;
• T3 – cancer has developed through the muscle in the fat layer;
• T3a – Fatty cancer can be seen only under the microscope (microscopic invasion);
• T3b – fatty cancer can be seen in the tests performed or felt by the doctor during an examination (macroscopic invasion);
• T4 – cancer has spread out of the bladder;
• T4a – cancer has spread to the prostate, uterus or vagina;
• T4b – cancer has spread to the pelvis or abdomen wall.

Nodules (N)– lymph nodes.

• NO – there is no cancer in any lymph node;
• N1 – cancer in a lymph node in the pelvis (between hip bones);
• N2 – cancer in more than one lymph node in the pelvis;
• N3 – cancer in one or more lymph nodes just outside the basin.

Metastasis (M)– metastasis describes whether cancer has spread to another part of the body.

• M0 – cancer has not spread to other parts of the body;
• M1 – cancer has spread to other parts of the body such as bones, lungs or liver

There is another staging system for bladder cancer that is not commonly used. It has 5 main stages, numbered from step 0 to step 4. The stage or stage 0 is the earliest cancer and 4 is the most advanced.

• Stage 0– Cancer is located only in the inner layer of the bladder lining (stage 0a) OR there are very early, very rare cancer cells in the inner layer of the bladder lining (stage 0).
• Stage 1– Cancer began to form in the connective tissue under the bladder mucosa.
• Stage 2– Cancer has increased through the connective tissue layer in the bladder wall muscle.
• Stage 3– Cancer increased through the muscle in the fat layer and spread to the prostate, uterus or vagina.
• Stage 4– Cancer spreads to the wall of the abdomen or the pelvis, the lymph nodes or other parts of the body such as bones, lungs or liver.