This page has been written for patients diagnosed with cancer in the colon (large bowel). It aims to help you understand the process involved in your care and make you aware of the various treatment options that might be available to you.

What is colon cancer?

The tissues and organs of the body are made up of cells. Cells age and become damaged and need to repair and reproduce themselves continuously. When this process gets out of control, the cells reproduce and multiply to form an abnormal mass (or tumour).

Tumours can be benign (not cancerous) or malignant (cancerous). A malignant tumour consists of cancer cells that can spread to other organs in the body.

Colon cancers are very common. They often develop from a growth known as a polyp, which usually start as benign tissue and over a period of time can turn cancerous. If this is caught early enough, there is the potential for many colon cancers to be cured. The most common type of colon cancer is an adenocarcinoma.

Although colon cancers are slightly more common in people who smoke and those who do not eat a diet rich in fruit and vegetables, most colon cancers arise without any particular cause being known. Very occasionally, cancers can be hereditary (run in families).

Ask your consultant or specialist nurse to indicate on the diagram (Figure 1 - In the PDF below) where the cancer (proven or suspected) is located in your body.


A diagnosis of colon cancer is proven by taking a biopsy (tissue sample) from the tumour to be examined under the microscope. A biopsy may be taken using a flexible sigmoidoscopy or colonoscopy (as described in this article).


To help us decide on your treatment, it is very important that we get the necessary information about the cancer and the rest of your body. This is called ‘staging investigations’ and can involve several tests which may include the following:

Computerised tomography (CT) scan

CT is a detailed X-ray examination of the body. It is used to look for abnormalities and in particular to see if there is any evidence that the cancer may have spread.

MRI scan

An MRI scan uses magnetism to build up a detailed picture of areas in your body. It is used to check whether a lump or abnormal area is cancer or to see the size of a cancer and whether it has spread.

Colonoscopy or flexible sigmoidoscopy

Colonoscopy or flexible-sigmoidoscopy tests both use a flexible tube with a light and a camera and will give a clear image of what the tumour looks like. A colonoscopy visualises the whole of the colon, whereas a flexible sigmoidoscopy is limited to views of the left side of the colon. These procedures can be used to take a biopsy of the tumour. If you are going to be offered keyhole (laparoscopic) surgery the area inside of the colon can then be marked with a tattoo. A colonoscopy also gives an opportunity to view the rest of the colon to check that there are no other tumours or polyps.

Carcino Embryonic Antigen (CEA) blood test

CEA is a tumour marker blood test that is used to measure the amount of chemical substance produced by a cancer. It can help to give information about the type and extent of the cancer.

The Multidisciplinary Team (MDT)

All of your results will be discussed at a colorectal cancer specialist multidisciplinary team meeting. This meeting takes place once a week and is attended by consultant colorectal surgeons, a consultant radiologist, a consultant histopathologist, a consultant clinical oncologist, colorectal clinical nurse specialists and other members of the colorectal team.

At this meeting the specialist team will use their expertise to determine what will be the most effective and appropriate form of treatment for you. The colorectal nurse specialists may be able to update you with the outcomes of the MDT meetings by telephone, if this has been previously agreed with you.

The treatment offered to you will be dependent upon the results of your staging investigations, your general health and other medical conditions. You will be offered an appointment with your consultant to discuss the treatment options open to you. You will be actively involved in any decision making and your views and wishes will be respected at all times.

Bowel resection

The primary treatment for colon cancer is an operation to remove the part of the colon containing the cancer. The operation you will require depends on exactly where the cancer is and the information provided by your staging scans.

In most cases, colon cancers can be removed and the bowel joined back up. However, it is sometimes necessary to make a temporary stoma (usually an ileostomy) to allow the join in the bowel to heal. An ileostomy is made by bringing a loop of the small bowel up to the surface of the abdomen where it is stitched in place and faeces (stools) will be passed into a bag which covers it. A temporary ileostomy is usually reversed after a minimum of 3 months.

If surgery is planned for you, you will be given a leaflet explaining the operation.

Staging of colon cancer

The exact stage of a colon cancer can often only be determined after surgery, when the pathologist can examine the cancer and the piece of healthy colon that has been removed.

The most commonly used system to stage colon cancer is the TNM staging. This gives more detailed information.

TNM staging system

Tumour - describes the tumour and how far it has invaded through the bowel wall.

Nodes - describes whether the cancer has spread to the lymph nodes.

Metastases - describes whether the cancer has spread to another part of the body such as the liver or lungs.

Post-operative radiotherapy and chemotherapy

Depending on the stage of your tumour, you may be offered a course of chemotherapy after your operation – this is known as adjuvant treatment.

Chemotherapy is ‘anti-cancer’ (cytotoxic) drugs used to destroy cancer cells in the body that remain after the tumour has been removed by surgery. It will also reduce the possibility of the cancer returning.

Radiotherapy treats cancer by using high energy rays to destroy the cancer cells. It is very unusual to give radiotherapy for colon cancer.

Clinical trials

There are a number of ongoing clinical trials relating to treatments for rectal cancer. If you are eligible to take part in any of these trials, this may be discussed with you by an oncologist or a clinical trials nurse.

What if my cancer has spread?

Sometimes colon cancers can spread to other organs in the body, most commonly the liver, lungs and peritoneum (lining of the abdominal cavity).

This is known as secondary cancer or metastases. If this is shown to be the case on your staging scans, then the treatment which can be offered will be dependent on the extent of the metastases.

In some circumstances it may be possible to offer surgery or other specialist therapies to treat metastases. These operations and therapies are not performed by Gloucestershire Hospitals NHS Foundation Trust so you would be referred to other specialist units.

Palliative treatment

If the spread of the cancer to other organs is extensive, you have decided to decline surgery or you are medically unfit for major surgery then you may be offered palliative radiotherapy and/or chemotherapy. This may help to control your symptoms and slow down progression of the disease but will not be a cure.


This is the insertion of a stent which is a flexible hollow tube that can be rolled up tightly and passed through the tumour. Once in place, stents are able to expand to keep the bowel open and prevent blockages. Stenting is subject to the position of the tumour.

Formation of a stoma

If it is not possible to offer you an operation to cure your cancer but you are getting a lot of adverse symptoms from your bowel being narrowed, you may be offered an operation to form a stoma. This may either be an ileostomy (formed from the small bowel) or a colostomy (formed from the large bowel). The aim would be to bypass the blockage and relieve your symptoms.

Best supportive care

If you are not medically fit to have any of the described treatments or you decide to decline treatment then you will be offered palliative or best supportive care. This is a treatment plan to relieve symptoms and aims to enhance quality of life for a long as possible.

Patient support

Being diagnosed with colon cancer will come as a shock to most people. As you progress through your treatment pathway you are likely to experience a rollercoaster of emotions. You will have lots of questions and concerns and often some difficult decisions to make.

You will be supported by the colorectal clinical nurse specialist team. Not only do we co-ordinate all of your tests and investigations but we will also provide specialist guidance and support. We are happy to talk to you about any part of your treatment pathway.

We will clarify any information that you have been given and give advice or lend a sympathetic ear if you are simply having a bad day. Further appointments to meet with your consultant will also be made as necessary.

Contact information

Colorectal Nurse Specialist

Gloucestershire Royal Hospital

Tel: 0300 422 5617

Monday to Friday, 9:00am to 4:00pm

Outside of these hours, please leave a message and someone will return your call the next working day.

Stoma Nurse Specialist

Cheltenham General Hospital

Tel: 0300 422 4363

Monday to Friday, 9:00am to 4:00pm

Gloucestershire Royal Hospital

Tel: 0300 422 6702

Monday to Friday, 9:00am to 4:00pm

Outside of these hours, please leave a message and someone will return your call the next working day.

If you have an urgent problem, the stoma nurses can be contacted via the hospital switchboard.

Gloucestershire Hospitals Switchboard

Tel: 0300 422 2222

When prompted, please ask for the operator then for the stoma nurses.

Further information

Macmillan Cancer Support

Tel: 0808 808 00 00

Monday to Friday, 9:00am to 8:00pm


Bowel Cancer UK


FOCUS Cancer Information Centre

Cheltenham General Hospital

Tel: 0300 422 4414

Monday to Friday, 8:30am to 4:30pm

Maggie’s Centre

College Baths Road, Cheltenham

Tel: 01242 250 611

Monday to Friday, 9:00am to 5:00pm

‘Mini’ Maggies

The Main Place, Old Station Way, Coleford, GL16 8RH

Tel: 01242 250 611

Offering practical and emotional support, facilitated and peer support groups as well as fitness and relaxation classes.

Sessions run on the third Friday of each month 10:00 am to 2:00 pm

Macmillan Information Hub

Gloucestershire Royal Hospital

Tel: 0300 422 8880

Monday to Friday, 9:00am to 4:00pm


To access the service either drop in (no appointment needed), call or email.

Printable version of this page

Colon cancer GHPI0583_11_22 Department: Colorectal Review due: November 2025 PDF, 394.2 KB, 9 pages
Reference number GHPI0583_11_22
Department Colorectal
Review due November 2025