Grading refers to the appearance of the cancer cells under the microscope. The grade gives an idea of how quickly the cancer may develop. The most common grading system uses three grades:

• grade 1 (low grade)
• grade 2 (moderate grade)
• grade 3 (high grade)

Low grade means that the cancer cells look very much like normal bladder cells. They are usually slowly growing and less likely to spread. In high-grade tumours the cells look very abnormal. They are likely to grow more quickly and are more likely to spread. In bladder cancer, carcinoma in situ (CIS) is always high grade.

Grading is important in early bladder cancer. It helps your doctor decide if you need extra treatment after the cancer has been removed.

The stage of a cancer describes its size and whether it has spread. Once your doctors know the stage of the cancer they can decide on the most appropriate treatment for you.

The most commonly used staging system for bladder cancer is called the TNM system:

• T is the size of the tumour (cancer)
• N is whether it has spread to the nearby lymph nodes (sometimes called glands)
• M is whether the cancer has spread to other parts of the body (metastases).

Early or superficial bladder cancer

• CIS  CIS (carcinoma in situ) is sometimes described as a flat tumour. Cancer cells are only in the inside layer of the lining of the bladder.
• Ta  There is a small area of cancer only in the bladder lining.
• T1  The cancer has started to grow into the layer of connective tissue beneath the bladder lining.

Invasive bladder cancer

• T2  The cancer has started to grow into the muscle of the bladder wall under the connective tissue layer.
• T2a  The cancer has grown through the superficial muscle.
• T2b  The cancer has grown deeply into the muscle.
• T3  The cancer has grown through the whole layer of muscle.
• T3a  The cancer has grown into the fat layer (beneath the muscle). This can only be seen when the tissue is examined under a microscope (microscopic).
• T3b  The cancer can be seen in the fat layer (macroscopic).

Locally advanced bladder cancer

• T4  The cancer has spread outside the bladder to any of the following: the prostate, womb and vagina, pelvic or abdominal wall.
• T4a  The cancer has spread to the prostate, womb or vagina.
• T4b  The cancer has spread to the pelvic or abdominal wall.

The N refers to whether the cancer cells have spread into the lymph nodes close to the bladder. There are four lymph node stages:

• N0 There are no cancer cells in any lymph nodes.
• N1 There are cancer cells in one lymph node smaller than 2cm across.
• N2 There are cancer cells in one affected lymph node larger than 2cm, but smaller than 5cm, or more than one node affected, but all of them smaller than 5cm across.
• N3 There are cancer cells in at least one affected lymph node larger than 5cm across.

If the cancer cells have spread to the lymph nodes, the nodes are described as positive.

If the cancer cells have not spread, this is described as M0.

M1 is when the cancer cells have spread to other parts of the body. This is called secondary, metastatic or advanced bladder cancer. If bladder cancer spreads, it’s most likely to go to the bones, the lungs or the liver.