What staging is

The stage (extent) of a cancer is one of the most important factors in choosing treatment options and predicting a man’s outlook. The stage of a cancer tells the doctor how far the cancer has spread. The tests and scans you have when diagnosing your cancer give some information about the stage.

TNM stages of prostate cancer

Prostate cancer is staged using the international **TNM system**. It separately assesses:

• the tumour (**T**)
• lymph nodes (**N**)
• secondary cancer (metastases – **M**).

T (tumour) staging

T1 tumours are too small to be seen on scans or felt during examination of the prostate – they may have been discovered by needle biopsy, after finding a raised PSA level.

T2 tumours are completely inside the prostate gland and are divided into 3 smaller groups:

• T2a – The tumour is in only half of one of the lobes of the prostate gland
• T2b – The tumour is in more than half of one of the lobes
• T2c – The tumour is in both lobes but is still inside the prostate gland

T3 tumours have broken through the capsule (covering) of the prostate gland but have not spread into other organs – they are divided into 2 smaller groups:

• T3a – The tumour has broken through the capsule (covering) of the prostate gland
• T3b – The tumour has spread into the seminal vesicles

T4 tumours have spread into other body organs nearby, such as the rectum (back passage), bladder, muscles or the sides of the pelvic cavity.

Stage T3 and T4 tumours are referred to as **locally advanced prostate cancer**.

N (lymph node) staging

Lymph nodes are described as being ‘positive’ if they contain cancer cells. If a lymph node has cancer cells inside it, it is usually bigger than normal. The more cancer cells it contains, the bigger it will be.

• NX – The lymph nodes cannot be checked
• N0 – There are no cancer cells in lymph nodes close to the prostate
• N1 – There are cancer cells present in lymph nodes

M staging – metastases (cancer spread)

• M0 – No cancer has spread outside the pelvis
• M1 – Cancer has spread outside the pelvis
• M1a – There are cancer cells in lymph nodes outside the pelvis
• M1b – There are cancer cells in the bone
• M1c – There are cancer cells in other places

As well as using the TNM staging, doctors put prostate cancers into 3 groups.

• Localised prostate cancer – completely contained within the prostate gland. Doctors will assess if it is at risk of growing quickly or whether it is likely to spread.
• Locally advanced prostate cancer – cancer that has broken through the outer covering (capsule) of the prostate gland.
• Metastatic prostate cancer – cancer that has spread to other parts of the body. Prostate cancer most commonly spreads to lymph nodes in other parts of the body or bones. It can spread to other organs though.

It is sometimes possible to have metastases (cancer spread) present even when the prostate tumour is still very small. So even if the tumour appears to be very small, when a bone scan shows that there is cancer in the bones, the prostate cancer is M1 stage. It will be treated as metastatic cancer and can often be controlled for several years with treatment.