Polyps are growths which can develop in many areas of the body, including the colon (large bowel). Polyps are benign growths (which means that they are non-cancerous), but they can become malignant and many doctors believe they are a major cause of bowel cancer. Polyps can vary in appearance and size, either protruding from a stalk or lying flat, and they can vary in size from less than a centimetre in diameter to several centimetres. In most cases, there is only a single polyp in the bowel, but it is possible for more than one to develop.
How common are polyps?
Polyps are very common, especially in Western countries, and it is estimated that around 1 in 4 people will have a polyp at some point in their lives. Polyps are more common in men than women and they tend to affect older people. Polyps are generally uncommon among those under the age of 40.
Types of polyp
There are different types of polyp, which include:
- Hyperplastic polyps: these are a very common form of polyp, which tend to be very small. In most cases, they do not cause any problems and are rarely associated with cancer.
- Adenomas: adenomas are also common and, although they tend to be small, they can grow much bigger. It is possible for adenomas to become cancerous; however, it is difficult to say how many cases become cancerous because there are different sub-types.
Polyps can also be symptomatic of syndromes known as polyposis syndromes, which are a group of rare hereditary conditions that cause polyps to form, usually affect young people and include familial adenomatous polyposis, Gardner syndrome and Turcot’s syndrome.
What causes polyps?
Polyps are caused by abnormal gene behaviour. Genes contain the information needed for hundreds of different processes in the body, including the renewal of the lining of the bowel. If the genes contain incorrect information the cells of the bowel lining can grow too fast, which causes growths (polyps) to form. Some polyps stay very small while others can grow to be fairly large. In most cases, the polyps remain benign, but in around 10% of people they can become cancerous.
How are polyps diagnosed?
Polyps are diagnosed by two tests: a barium enema X-ray and a colonoscopy. Both procedures require the bowel to be empty, so your doctor will advise you about eating and drinking prior to the procedure. A colonoscopy involves using a colonoscope, which is a long, thin flexible tube, fitted with a camera and allows doctors to see the inside of the bowel. The procedure only lasts around 20-30 minutes and you will be sedated to prevent any pain or discomfort. A barium X-ray enables doctors to see clear X-ray images of the colon. A thick liquid that contains barium is used as an enema but it is also possible to eat a barium meal, which is known as a barium swallow.
In many cases, polyps are diagnosed during investigations carried out when a patient has symptoms that suggest a problem with the bowel (for example, if they notice changes in their bowel habits or traces of blood are noticed in the faeces). This is because polyps rarely cause symptoms.
When you see your doctor, they may ask you about your family history, as polyps and bowel cancer can run in families (although this is often not the case). If you have a strong history of polyps and bowel cancer, you may be advised to have a screening test.
Symptoms of polyps
In the majority of cases, polyps do not cause symptoms and many people are unaware that they have polyps. However, symptoms can develop in some cases. Possible symptoms include:
- Bleeding from the anus.
- Mucus in the faeces.
- Constipation and diarrhoea (this is rare).
Treatment for polyps
The usual treatment for polyps involves removing the polyp. In most cases, polyps do not cause any symptoms or problems, but it is possible for them to become cancerous, so it always best to remove them. Most polyps can be removed during a colonoscopy. The colonoscope is fitted with grabbing devices, which can be controlled by the doctor and used to remove the growth. The procedure is fairly simple and painless. Once the growth has been removed, it will be sent to the laboratory for analysis, which will determine the type of polyp and check for signs that the polyp may be cancerous. In most cases, lab tests show the growth is benign and confirm the polyp has been removed completely.
After the polyp has been removed your doctor may organise a follow-up appointment to check your progress. If the polyp was found to have cancerous signs, your doctor will arrange another colonoscope to check for the development of new polyps.
Will I need to change my diet?
It is not usually necessary to change your diet, but you should ensure that you have a healthy, balanced diet. Aim for at least five portions of fruit and vegetables each day and take in plenty of fluid.