The stage of a large bowel or rectal neuroendocrine tumour (NET) tells you about its size and whether it has spread. Knowing the stage can help your doctor decide which treatment you need.
You have tests and scans to diagnose a NET. These give some information about the stage of the cancer. Sometimes it’s not possible to be certain about the stage until after surgery.
In the UK, doctors usually use a staging system called TNM. TNM stands for tumour, node and metastasis:
- T describes the size of the tumour
- N describes whether there are any cancer cells in the lymph nodes
- M describes whether the tumour has spread to a different part of the body
Tumour describes the size of the cancer. It is divided into 4 main stages.
This is a simplified description of the T stages:
The tumour is no bigger than 2 cm. It has only grown into the inner lining of the bowel (the mucosa), or into the next layer (the submucosa).
The tumour has grown into the muscle layer of the bowel wall. Or the tumour is bigger than 2 cm.
The tumour has grown through the muscle layer and into the first part of the outer lining of the bowel wall.
The tumour has grown through the outer lining of the bowel wall. Or into a nearby organ or structure.
The N stage describes whether the cancer has spread to the lymph nodes.
N0 means there are no lymph nodes containing NET cells.
N1 means there are NET cells in the nearby lymph nodes.
The M stage describes whether the tumour has spread to a different part of the body.
M0 means the cancer has not spread to other areas of the body.
M1 means the cancer has spread to other areas of the body, such as the liver.
The stage of a NET helps your doctor decide which treatment you need. Treatment also depends on how much the NET cells look like normal bowel cells (grade).