Diet after anal cancer treatment

Why you might need to change your diet

You might need to change what you eat after treatment for anal cancer. Your digestion may need time to settle down. And some foods can upset the way the bowel and a colostomy works.

This may be a temporary change after treatment. If you find the problem continues, speak to your healthcare team.

What changes you may need to make

This can depend on what treatment you have. But there is nothing you absolutely cannot eat.

If you have problems such as loose poo or wind it is unlikely to be caused by what you are eating. It is more likely to be due to the effects of treatment. These problems can settle after a couple of months, but you should still let your doctor or specialist nurse know.

Try and have a balanced diet. This means eating foods from all the food groups that your body needs. Tell your doctor or specialist nurse if you are struggling with this and not managing to eat well.

If you follow a special diet for a health condition such as diabetes, it is important that you continue it. Speak to your doctor or specialist nurse if you think this will be a problem.

Eating after anal cancer surgery

Any changes to your diet will depend on what operation you've had. Depending on the stage and where the cancer is in your anus, your surgeon might remove either:

• just the cancer and a small area of healthy tissue (margin) around it - doctors call this a local resection

• your anus, back passage (rectum) and the last part of your bowel - this is called an abdominoperineal resection

Local resection

After a local resection you should be able to eat and drink normally.

Abdominoperineal resection (APR)

You normally need to slowly build up what you are eating after an abdominoperineal resection. And your healthcare team may also ask you to have readymade nourishing drinks whilst you are in hospital. By the time you go home, you should be able to eat properly again.

You have a colostomy after an abdominoperineal resection. And what you eat and drink may affect how this works.

Read more about surgery for anal cancer

Eating after a colostomy for anal cancer

If you have a colostomy, following these tips in the days and weeks after surgery may help:

• Eat small meals but more often.

• Eat a high amount of protein such as chicken, fish, tofu and dairy products.

• Chew your food well. It can help to avoid indigestion.

If you don’t have much appetite, try:

• eating the foods you enjoy

• having frequent snacks

• choosing foods that are higher in calories

These can stop you from losing too much weight.

Your stoma nurse will also give you advice on your diet when you have a colostomy.

Foods that can cause wind or loose poo

Some foods can cause wind or loose poo. Foods that are often a problem include:

• high fibre fruits and vegetables

• pure fruit juice

• onions and cabbage

• beans and pulses

• fizzy drinks and beer

• rich or fatty foods

• artificial sweeteners

Speak to your stoma nurse if you have wind or loose poo. They can give you tips on how to reduce the effects. But you might need to experiment to find out which foods are causing it. And sometimes it may be due to other factors such as:

• when you eat

• how quickly you eat

• a stomach bug

• some medicines

Find out more about coping with a colostomy

Eating after radiotherapy for anal cancer

Radiotherapy for anal cancer can cause frequent loose poos. You might also find you need to poo urgently. This is because the radiotherapy can make your rectum irritated and swollen. It usually settles down a few weeks after treatment has finished. But it may continue for some people.

Your doctor can prescribe medicines to reduce the swelling in your rectum. And some people also avoid alcohol and caffeine as they find it makes their bowel symptoms worse.

Your doctor might also recommend you change the amount of fibre you eat. Fibre keeps the bowels working regularly. It is also called roughage.

There are different types of fibre including:

• insoluble fibre – helps poo absorb water. This makes the poo bulky so it moves through the bowel easier, which can irritate the bowel after radiotherapy

• soluble fibre – dissolves in the bowel and becomes jelly-like. This slows the poo as it moves

If you have frequent loos poos, your doctor may ask you to have a diet that is low in insoluble fibre and high in soluble fibre. This means the poo will move slower and not as easily through the bowel.

Over time, you should be able to start eating the foods high in insoluble fibre again.

Having less insoluble fibre

If your doctor suggests you reduce the amount of insoluble fibre you eat, try avoiding foods such as:

• wholegrain cereals such as muesli and seeded bread

• fruits and vegetables that have a lot of fibre in them such as celery and rhubarb

• the skin, pips and seeds of fruits and vegetables

• raw vegetables

• vegetables that aren’t broken down in the digestive system such as sweetcorn, mushrooms and salad leaves

• fruit juice with bits

• beans and pulses

Having more soluble fibre

To increase the amount of soluble fibre you eat, helps to have more foods such as:

• wholemeal bread products

• fruits without the skins, pips or seeds

• root vegetables

• porridge

Read more about radiotherapy side effects

Eating after chemotherapy for anal cancer

A combination of chemotherapy and radiotherapy (chemoradiotherapy) is the main treatment for anal cancer. The chemotherapy can give you side effects that make it difficult for you to eat normally. This might include feeling sick, a sore mouth or diarrhoea.

Find out more about coping with the side effects of cancer drugs

These side effects will disappear after your treatment is over. But you may have to change what you eat until they fully stop. Over time, you will be able to get back to a regular diet.

If you are struggling, try and eat small meals with snacks throughout the day. And choose higher calorie foods. This can help prevent weight loss and help you recover after treatment has finished.

Seeing a dietitian

If you are having problems with eating, your hospital can refer you to a dietitian. They can give you information and advice on:

• food and eating

• eating more

• managing symptoms that are affecting your diet

Read more about diet problems and cancer