Colon Polyps

What is a colon polyp?

Colon polyps are growths that arise from the inner surface of the large bowel and grow into the cavity of the bowel.

Polyps are quite common, and become more likely as age advances. Most polyps are benign and cause no complaints at all.

But some kinds of polyp can grow over years and carry the potential to turn into bowel cancer.

For this reason the importance of colon polyps is not merely that there is a growth in the bowel. Finding and removing, in good time, the polyps that carry the potential to become cancer can help prevent bowel cancer.

Is every colon polyp a cancer?

No. Seeing a polyp does not mean you have cancer.

The great majority of colon polyps are not cancer at the time they are found.

There are different kinds of polyp, and their risks of turning into cancer are not the same.

The potential of some polyps to become cancer is very low, while others are more likely to progress to cancer over time.

For this reason, when a polyp is found at colonoscopy it matters that it is removed where possible and sent for pathological examination where needed.

What kinds of colon polyp are there?

The exact kind of a polyp is mostly established by pathological examination after it has been removed.

Adenomas

Adenomas are one of the kinds of polyp seen often in the large bowel.

Because some of them carry the potential to turn into cancer over time, they are considered among the precancerous lesions.

But finding an adenoma does not mean cancer is present.

Removing an adenoma aims to end the possible process of becoming cancer while there is still no cancer.

Serrated lesions

In the past some serrated polyps were thought unimportant. Today it is known that certain serrated lesions in particular may play an important part in one of the pathways by which bowel cancer develops.

Sessile serrated lesions in particular may be found mostly in the right colon, and their flat shape can sometimes make them harder to notice than classical stalked polyps.

Hyperplastic polyps

Most hyperplastic polyps are small, and the risk of becoming cancer in the small hyperplastic polyps found in the rectum and sigmoid colon in particular is generally very low.

Even so, the site, the size and the pathological features of the polyp matter in the assessment.

Are polyps all the same shape?

No.

Some polyps are attached to the bowel wall by a stalk. These are called stalked (pedunculated) polyps.

Others sit on the bowel wall on a broad base and are called sessile polyps.

Some lesions rise only very slightly from the surface of the bowel, or are almost flat.

Because flat lesions in particular can be harder to notice, good bowel cleansing and a good-quality colonoscopic examination matter.

Why do colon polyps form?

There is no single cause for the formation of a polyp.

The cells of the inner surface of the bowel are normally renewed continuously. Genetic and cellular changes occurring over time in the mechanisms that control the growth of these cells can cause some cells to multiply more than normal and a polyp to develop.

Many factors — age, genetic susceptibility and lifestyle among them — can play a part in this process.

In whom is the risk of colon polyps higher?

Polyps can develop in anyone. Even so, the risk is higher in some people.

The risk may be increased particularly:

• At an advanced age,
• In people in whom a colon polyp has been found before,
• In those with bowel cancer or advanced polyps in the family,
• In people with certain inherited polyp and cancer syndromes,
• In certain long-standing inflammatory bowel diseases,
• In smokers,
• In people with obesity,
• In people with low physical activity.

Even so, polyps can develop in people with no risk factors at all.

For this reason bowel cancer screening is not directed only at people with complaints or a family history.

Do colon polyps cause symptoms?

Most colon polyps cause no symptoms at all.

A polyp may be found at a colonoscopy done for screening while the person feels entirely healthy.

This also explains why bowel cancer screening matters.

In some polyps there may be findings such as:

• Blood in the stool,
• Bleeding from the back passage,
• Iron deficiency or anaemia,
• A change in bowel habit.

But these complaints are not specific to polyps. They can arise from many different causes, from haemorrhoids to bowel diseases.

For this reason complaints that are unexplained or continuing in particular need to be assessed.

Do polyps cause pain?

Mostly, no.

The great majority of colon polyps do not cause pain.

For this reason the thought “I have no pain, so I cannot have polyps in my bowel” is not correct.

A substantial proportion of polyps are found without having given any symptom.

How are colon polyps diagnosed?

One of the most important methods for finding colon polyps is colonoscopy.

The inner surface of the large bowel can be examined directly during colonoscopy. If a polyp is found it can in most cases be removed during the same procedure.

This is one of the important advantages of colonoscopy: a polyp can be both found and, where suitable, removed as treatment during the same procedure.

Faecal occult blood tests and certain imaging methods can also be used in bowel cancer screening. But where these tests give a suspicious result, or where a polyp is suspected, colonoscopic assessment is generally needed.

Should every polyp seen at colonoscopy be removed?

Most suitable colon polyps, and lesions that may carry the potential to become cancer in particular, are removed during colonoscopy.

But not every polyp is removed by the same method or at the same session.

Advanced endoscopic methods may be needed for polyps that are very large, broad-based, in a difficult location, or suspected of extending into the deeper tissues.

In that case the polyp may be removed by advanced methods such as:

• Endoscopic mucosal resection (EMR),
• Endoscopic submucosal dissection (ESD),

or surgical assessment may be needed in suitable patients.

Seeing a large polyp does not necessarily mean an operation is needed.

Which polyps carry a higher risk of becoming cancer?

The risk a polyp may pose in the future is not established by looking at one feature.

In assessing the risk, what is taken into account is particularly:

• The size of the polyp,
• The number,
• The pathological kind,
• The cellular features,
• The degree of dysplasia,
• Whether it was removed completely.

In general, as a polyp grows the likelihood of its carrying advanced pathological features may increase.

But a small polyp is not necessarily unimportant, nor is a large polyp necessarily cancer.

The definite assessment is made together with the pathology result.

What is dysplasia?

One of the terms patients may come across in pathology reports is “dysplasia”.

Dysplasia means that there are changes in the polyp cells that differ from normal.

These changes are not cancer; but some of them may be part of the process leading to the development of cancer.

For this reason terms such as “low-grade dysplasia” or “high-grade dysplasia” may be seen in the pathology report.

In polyps with high-grade dysplasia in particular, it matters that the polyp has been removed completely and that follow-up is appropriate.

If a polyp is removed, does it come back?

If the polyp removed was taken completely, that same polyp is generally gone.

But new polyps may develop over time in other parts of the person’s bowel.

For this reason removing a polyp does not mean that no polyp will ever form again in that person’s lifetime.

That is why a repeat colonoscopy at set intervals is advised for some patients.

When should a colonoscopy be repeated after a polyp has been removed?

The same interval is not given to every patient.

The timing of the next colonoscopy is decided according to:

• The number of polyps removed,
• Their size,
• The pathology result,
• Whether the polyps were removed completely,
• Whether the bowel cleansing at the first colonoscopy was adequate,
• Family history,
• And the person’s other risk factors.

For some people a check at long intervals may be enough, while people with advanced features or with many polyps may need an earlier check.

For this reason it is not right to compare your own interval with another patient’s.

If there are polyps in my family, do I need a colonoscopy too?

Family history matters.

Bowel cancer or advanced polyps in first-degree relatives in particular — mother, father, siblings or children — can affect a person’s risk.

At what age screening begins and by what method can vary with the relative’s age, the kind of disease and the number of people affected in the family.

For this reason it matters that you tell your doctor your family history.

Is it possible to prevent colon polyps?

It is not possible to prevent all polyps. There are factors that cannot be changed, such as age and genetic susceptibility.

Even so:

• Not smoking,
• Keeping to a healthy body weight,
• Taking regular physical activity,
• Eating a balanced diet rich in vegetables, fruit, wholegrains and fibre,
• Limiting processed and excessive red meat,
• Avoiding excessive alcohol

can be useful for general bowel health and for reducing the risk of colorectal cancer.

But a healthy way of living does not take the place of the recommended screening tests.

What is the most important thing about colon polyps?

The most important thing about colon polyps is that most can develop without symptoms and that some kinds can turn into cancer over years.

That process also gives an important opportunity.

When a polyp with the potential to become cancer is found in good time and removed completely, the intervention has come before the cancer developed.

For this reason colonoscopy is an important method used not only to diagnose bowel cancer but to prevent it.

Colon polyps in brief

Colon polyps are growths arising from the inner surface of the large bowel.

Not every polyp is cancer. Most polyps cause no symptoms. Some kinds of polyp can turn into cancer over time.

Colonoscopy allows polyps to be found and, most of the time, removed at the same session.

Pathological examination of the polyp removed matters in establishing the future risk.

Because new polyps can develop in people in whom a polyp has been found before, follow-up at appropriate intervals may be needed.

Finding polyps early and removing the suitable ones is one of the most effective ways of preventing bowel cancer.

This information has been prepared for general patient information. When bowel cancer screening begins, and the follow-up intervals after a polyp has been found, can vary with the person’s age, their family history, the colonoscopy findings and the pathology result. The follow-up programme suitable for you should be decided by your doctor.