Bowel changes after bowel cancer treatment

Late effects are side effects that do not go away, or that start months or years after treatment. The most common late effect of bowel cancer treatment is a change in how the bowel works.

Most people have bowel changes after surgery or radiotherapy for colon, rectal or anal cancer (bowel cancer).

Your bowel habits may not go back to the way they were before treatment. But over time, bowel symptoms usually become less troublesome. Most people find they get into a new routine that becomes normal for them. This can take a year or more.

If you have ongoing bowel problems, or any of the symptoms listed below, there are many things that can help. Your doctor or specialist nurse can give you advice.

Many people find changing their diet and taking anti-diarrhoea drugs stops the diarrhoea. But if this does not help, ask your doctor to refer you to a gastroenterologist. Lots of different things can cause diarrhoea, and a gastroenterologist will be able to do a full assessment.

After bowel cancer treatment, particularly pelvic radiotherapy, some people have diarrhoea caused by changes to the small bowel, such as:

• bile acid malabsorption (also called bile acid diarrhoea)
• small bowel bacterial overgrowth.

Bile acids are made in the liver and go to the small bowel when you eat to help digest fats. When the bile acids reach the far end of the small bowel, they are absorbed back into the body.

Sometimes, radiotherapy for bowel cancer damages the small bowel. Or, part of the small bowel may be removed during surgery. If the small bowel cannot re-absorb the bile acids, this can cause watery diarrhoea, painful cramping and bloating. This is called bile acid malabsorption or bile acid diarrhoea.

Your doctor may advise you to start the following treatments, to see if symptoms improve:

• Eating a low-fat diet – a dietitian will help you do this in a balanced way.
• Taking anti-diarrhoea drugs.
• Taking drugs that reduce the effect of bile acids on the bowel – the drug most commonly used is colestyramine (Questran^®, Questran Light^®). It is a powder that you mix with water or fruit juice. If colestyramine does not work, your specialist may prescribe a tablet called colesevelam (Cholestagel^®).

A scan called a SeHCAT scan can help diagnose bile acid malabsorption. Your doctor can explain more about this test. SeHCAT scans are not widely available and may not be needed.

Most people with bile acid malabsorption do not absorb enough vitamins and need to take vitamin supplements. Your doctor can talk to your more about this.

The large bowel contains lots of healthy or ‘good’ bacteria, which help digest food. But a healthy small bowel contains almost no bacteria. After pelvic radiotherapy, sometimes this changes and bacteria are found in the small bowel. This is called small bowel bacterial overgrowth, or SIBO. It can cause symptoms, including:

• diarrhoea
• wind
• bloating
• constipation
• feeling sick
• omiting
• bad breath.

A breath test can help to find out whether you have small bowel bacterial overgrowth. You have the test as an outpatient. Samples of your breath are tested for signs of bacteria in your small bowel.

Small bowel bacterial overgrowth is usually treated with antibiotics.

Tenesmus is the feeling that you need to go to the toilet but your bowel is empty. It can involve straining, pain and cramping.

Tell your doctor or nurse if you have these symptoms.

We have more information about tenesmus.

If you have problems with wind after bowel cancer treatment, the following tips may help:

• Cut down on foods and drinks that are causing wind.
• Eat your meals at the same times each day.
• Do not eat and drink at the same time.
• Use pelvic floor exercises to strengthen the muscles used for bowel control.
• Ask your doctor for advice if you take medicines that cause wind, such as Lactulose^® or Fybogel^®.
• Try taking peppermint oil or eating live yoghurts. Or you could try taking charcoal tablets, which you can buy from the chemist. However, charcoal can affect other medicines you may be taking so always ask your doctor or pharmacist first.

Tell your doctor if this symptom is a problem. Sometimes other things may be making wind worse. For example, constipation or bowel conditions, such as diverticular disease can make wind worse. Wind can also be a symptom of a food intolerance, or a condition called small bowel bacterial overgrowth after radiotherapy.

Ongoing diarrhoea or leaking (incontinence) from the bowel can make the skin around the anus sore. Sometimes radiotherapy for rectal or anal cancer can also make this area of skin sore, red or broken.

If your skin is sore or passing a bowel movement is painful, speak to your doctor or nurse. They can give you advice about looking after your skin and may give you creams or ointments to use. They can also check your skin for signs of other problems such as piles (haemorrhoids) or fissures.

Normally, tissues and organs inside the tummy (abdomen) are slippery and move easily as the body moves. After surgery in the abdomen, bands of scar tissue (called adhesions) may form between abdominal tissues and organs, sticking them together.

Adhesions often do not cause any problems. But sometimes they can cause pain.

Rarely, adhesions can make part of the bowel twist or kink, pulling it out of place so that it becomes blocked.

We have more information about adhesions.

A fistula is an opening that forms between areas of the body that are not usually connected. Rarely after pelvic radiotherapy or surgery for rectal or anal cancer, an opening can develop between:

• the rectum and vagina
• the rectum and bladder or urethra.

Sometimes a fistula closes on its own. It can then be managed with treatment to control symptoms. If this does not happen, it may be possible to have an operation to close it.

We have more information about fistulas.