Patients may be referred for a number of investigations and scans in order to find out if they have a colorectal cancer. These investigations also allow the specialist team to make a diagnosis.
Diagnostic investigations
Diagnostic investigations may include:
- Colonoscopy or flexible sigmoidoscopy – a long, flexible camera is used to look at the colon and rectum. Biopsies can be taken and polyps can be removed during the procedure.
- CT scan – a series of x-rays are taken to build up a three-dimensional picture of inside the body. The CT scan produces detailed images of many structures inside the body, including internal organs, bones and blood vessels. CT stands for Computer Tomography.
- CT Colonography (CTC) – a test which uses CT scans to produce detailed images of the large bowel and rectum. It is also called a virtual colonoscopy.
- MRI – a type of scan that uses strong magnetic fields to produce detailed images of soft tissue (flesh) inside the body. MRI stands for Magnetic Resonance Imaging.
- PET scan – this scan uses a mildly radioactive drug to show up any areas of the body where cells are more active than normal. It can help to find out if and where the cancer has spread. PET stands for Positron Emission Tomography, and is only done in the Royal Group of Hospitals in Belfast.
Staging of Colorectal Cancer
Your specialist team needs certain information about the cancer to decide on the most appropriate treatment for you. This includes the stage of the cancer, which describes its size and whether it has spread anywhere else in the body.
The TNM system is the most commonly used staging system:
- T – describes how far the tumour has grown into the wall of the bowel, and whether it has grown into nearby tissue or other organs.
- N – describes whether the cancer has spread to the lymph nodes.
- M – describes whether the cancer has spread to another part of the body such as the liver or lungs (metastatic or secondary cancer).
Read more about the staging and grading of each colorectal cancer (Macmillan).