Cancer starts when cells in our body divide and grow in an uncontrolled way. These abnormal cells can grow into surrounding tissues and organs. They may also spread to other parts of the body.

Cancer that affects the large bowel is usually called bowel cancer. It is also known as colorectal cancer (CRC). The large bowel includes the colon and the rectum.

Bowel cancer symptoms

Bowel cancer symptoms can be like Crohn’s and Colitis symptoms. They include:

• Bleeding from your bottom.
• Blood in your poo.
• Long-lasting and unexplained changes in your bowel habits. This could include looser poos or pooing more than is usual for you.
• Unexplained weight loss.
• Fatigue or feeling very tired.
• A pain or lump in your tummy.

Most people with these symptoms do not have bowel cancer. But if something does not feel right or you are worried about any of your symptoms, speak to your GP or IBD team.

Who is at risk?

Bowel cancer is the fourth most common cancer in the UK. In the general population in the UK, about 6 in 100 men and 5 in 100 women will be diagnosed with bowel cancer during their lifetime.

You are more likely to develop bowel cancer than the general population if:

• You have Crohn’s Disease that affects the colon (also known as Crohn’s Colitis)
• You have Ulcerative Colitis

But the actual increase in the risk of developing bowel cancer if you have Crohn’s or Colitis is low. And over the last 20 years, the number of people with Crohn’s or Colitis who develop bowel cancer has fallen. This could be due to screening by colonoscopy and better medicines.

If you have Ulcerative Colitis

If you have Ulcerative Colitis, the risk of developing bowel cancer is linked to how much of your large bowel is affected:

• The risk of developing bowel cancer is highest if you have extensive, total or pancolitis. This is when inflammation affects all, or most, of your colon.
• If you have distal or left-sided colitis, the risk of developing bowel cancer is lower than people with total colitis, but higher than in the general population. Distal or left-sided colitis is when inflammation affects only the left side of your colon.
• Having proctitis does not increase your risk of developing bowel cancer. Proctitis is when only your rectum is affected by Ulcerative Colitis.

If you have Crohn’s Disease

Having Crohn’s Disease that affects much or all of your colon increases the risk of developing bowel cancer. Having Crohn’s Disease that does not affect your colon does not increase the risk of developing bowel cancer.

If you have Microscopic Colitis

The risk of bowel cancer in people with Microscopic Colitis is lower than in the general population.

Other risk factors

There are other things that can increase the risk of bowel cancer.

Other risk factors related to Crohn’s and Colitis include:

How long you have had Ulcerative Colitis or Crohn’s Colitis

Bowel cancer risk increases with time. The risk starts to increase about 8 to 10 years after the start of your symptoms. This is not from the date of your diagnosis, which could be much later than when your symptoms started.

Severity of inflammation

Your risk of bowel cancer is higher if you have severe ongoing inflammation.

Strictures

Ongoing inflammation and then healing in the bowel may cause scar tissue to form. This can create a narrow section of the bowel known as a stricture. Strictures can also be caused by severe inflammation alone. Your risk of bowel cancer is higher if you have strictures.

Primary sclerosing cholangitis (PSC)

Having primary sclerosing cholangitis (PSC) increases the risk of bowel cancer in people with Crohn’s or Colitis.

PSC is an inflammatory condition affecting the bile ducts. Your bile ducts are tubes that connect your gallbladder and liver to your small bowel. Bile ducts carry bile which helps to digest food. In PSC, bile builds up in your liver, causing liver damage.

PSC affects about 1 in every 100 people with Ulcerative Colitis and 1 in every 200 people with Crohn’s Disease.

Find out more about primary sclerosing cholangitis (www.gutscharity.org.uk).

Dysplasia in the large bowel

Your risk of bowel cancer increases if dysplasia has been seen in your bowel during a previous colonoscopy. See the section on Surveillance colonoscopies.

Family history of bowel cancer

Your risk of bowel cancer increases if anyone in your family has had bowel cancer, even if they don’t have Crohn’s or Colitis. This risk is highest in people with a close relative (parent, sibling or child) diagnosed with bowel cancer before they were 50.

Sex

The risk of bowel cancer in people with Crohn’s or Colitis is slightly higher in men than in women.

Age at diagnosis of Crohn’s or Colitis

Being diagnosed with Crohn’s or Colitis before the age of 30 years also increases the risk of developing bowel cancer.

Risk factors not related to Crohn’s or Colitis

You may also be more likely to get bowel cancer if:

• You are over 50 years old. But it is still important to be aware of bowel cancer symptoms at any age.
• You have a history of non-cancerous growths (polyps) in your bowel.
• You have Type 2 diabetes.
• You eat a lot of processed food and red meat.
• You are overweight or obese.
• You are physically inactive.
• You smoke.
• You drink alcohol. For cancer prevention, it’s best not to drink alcohol at all. If you do drink alcohol, keep it as low as possible with an upper limit of no more than 14 units a week and try to spread it out over the week.

What is the risk?

The risk of developing bowel cancer increases with the amount of time that you have had Crohn’s Colitis or Ulcerative Colitis. Research estimates that:

• 1 in every 100 people with Crohn’s Colitis or Ulcerative Colitis might develop bowel cancer after 10 years of symptoms.
• 2 in every 100 people with Crohn’s Colitis or Ulcerative Colitis might develop bowel cancer after 20 years of symptoms.
• 5 in every 100 people with Crohn’s Colitis or Ulcerative Colitis might develop bowel cancer after more than 20 years of symptoms.

Reducing your risk

You cannot always prevent bowel cancer, but there are things you can do to lower your chance of getting it.

Follow your treatment plan

Long-term inflammation is linked to developing bowel cancer. Following your treatment plan and taking your medicine as prescribed gives your bowel a chance to heal. This may reduce your risk of developing bowel cancer.

Taking azathioprine, mercaptopurine or 5-ASAs (aminosalicylates) has been linked to a lower risk of developing bowel cancer.

Try to keep in touch with your IBD team and attend your appointments, even when you feel well. Your IBD team can help you find ways to manage your condition effectively, including helping you find the best treatment. Speak to your GP or IBD team if you notice any changes in your symptoms that you’re worried about.

Have regular colonoscopies

Regular colonoscopies allow specialists to check for early changes in the colon before cancer develops.  This is known as a surveillance colonoscopy.

See the section on Surveillance colonoscopies for more information.

Make healthy lifestyle changes

Some of the lifestyle changes you can make to reduce your risk of bowel cancer include:

• Being more active. Take a look at our information on being active with Crohn’s or Colitis for tips to help you exercise.
• Reducing how much red and processed meat you eat.
• Reducing how much alcohol you drink. For cancer prevention, it’s best not to drink alcohol at all.
• Stopping smoking if you smoke. You can get help from Quit smoking - NHS (www.nhs.uk)
• Eating plenty of fibre from wholegrains, pulses, vegetables and fruit. For some people with Crohn’s or Colitis, increasing fibre makes symptoms worse. Increase your fibre intake gradually to reduce wind and bloating. You should not increase your fibre intake if you have a stricture. See our information on Food for tips on increasing the amount of fibre in your diet.

See Bowel Cancer UK for more details on reducing your risk through lifestyle changes.

Surveillance colonoscopies

A surveillance colonoscopy is a ‘check-up’ colonoscopy. Its aim is to look for anything odd in the lining of the colon and rectum that might suggest a higher risk of bowel cancer.

When should I be offered my first surveillance colonoscopy?

 You should be offered a surveillance colonoscopy if:

• You’ve had Crohn’s affecting your colon for 8 years
• You’ve had Ulcerative Colitis affecting the left side, or all of your colon for 8 years
• You have Crohn’s or Ulcerative Colitis and are diagnosed with primary sclerosing cholangitis (PSC)

If you have proctitis (Ulcerative Colitis in your rectum) you won’t need surveillance colonoscopies unless your colon also becomes inflamed. This is because having proctitis does not increase your risk of developing bowel cancer.

During the colonoscopy, the specialist will look at the lining of the colon and rectum. In particular, they will look for:

• How inflamed it is
• The presence of polyps or dysplasia

The specialist may remove polyps or tissue samples so they can check them under a microscope.

How often should I have a surveillance colonoscopy?

How often you have a follow up colonoscopy will depend on your risk of getting bowel cancer. You will usually have a surveillance colonoscopy every 1 to 5 years. Your risk will have been set at your most recent colonoscopy:

• If you are at low risk, you should be offered a surveillance colonoscopy every 5 years.
• If you are at medium risk, you should be offered a surveillance colonoscopy every 3 years.
• If you are at higher risk, you should be offered a colonoscopy every year.

You are at higher risk of developing bowel cancer if:

• You have Crohn’s or Ulcerative Colitis and PSC
• You have active inflammation affecting most or all of your colon
• You have a colonic stricture or have had dysplasia detected during a previous colonoscopy
• A close family member (parent, sibling or child) developed bowel cancer before the age of 50

It is recommended that people with Crohn’s or Colitis and PSC have a surveillance colonoscopy every year. This should start from when you are first diagnosed with both conditions. See the section on Reducing your risk.

It’s best to have a surveillance colonoscopy when your Crohn’s or Colitis is in remission, if possible. This is because it can be difficult to see dysplasia if your bowel is very inflamed.

Effectiveness of surveillance colonoscopies

Colonoscopy is the best way to detect bowel cancer early, and even prevent it. Bowel cancer can be prevented by removing pre-cancerous polyps during a colonoscopy.

But sometimes cancer or dysplasia (pre-cancerous changes) can be missed during a colonoscopy. This might happen because:

• It is not always possible to reach the entire large bowel during a colonoscopy
• The bowel preparation (bowel prep) might have not cleaned the bowel enough to see the cancer or dysplasia
• Small, flat areas of dysplasia can be difficult to see
• Ongoing bowel inflammation may make it difficult to see the cancer or dysplasia
• In some cases, a polyp may not have been removed fully so cancer later develops

The colonoscopy will usually last around 30 to 45 minutes. To help you feel more comfortable, you may be offered:

• Painkillers
• Sedation – a medicine to help you feel sleepy and relaxed.
• Nitrous oxide - a medicine to help you relax that you breathe in, known as ‘gas and air.’

We understand that you may feel nervous or worried about having a colonoscopy. But if you have an appointment for a colonoscopy, it's important that you attend. The earlier bowel cancer is found, the more likely it can be treated successfully. Talk to your IBD team about the risks and benefits of having regular colonoscopies.

If you think you are due to have a surveillance colonoscopy but have not been invited for one, contact your IBD team. Contact your IBD team or GP if you’re worried about any of your symptoms in between colonoscopies.

Bowel cancer screening

The NHS bowel screening programmes in the UK are for everyone, whether you have Crohn’s or Colitis or not.

You’ll use a home testing kit called the faecal immunochemical test (FIT). You will usually be sent this when you reach a certain age, depending on where you live. FIT looks for tiny amounts of blood in a small sample of your poo. It is different to the faecal calprotectin test, which is a poo test that looks for signs of inflammation in your gut.

You should complete the FIT test even if:

• You are already in the surveillance colonoscopy programme
• You have had a recent endoscope
• You are in a flare-up

The FIT test may show blood in your poo that needs further investigation. In this situation a healthcare professional will assess you. They should discuss with you any previous investigations or treatment. And they should provide support and advice on the next steps and whether you have any further investigation. This will usually be a colonoscopy. Blood in your poo won’t always mean you have cancer. Your FIT may show blood in your poo due to Crohn’s or Colitis.

 The age when you are offered FIT depends on where you live in the UK. See detailed information for your nation:

• England
• Northern Ireland
• Scotland
• Wales

Find out more about Bowel cancer screening (www.nhs.uk)

If you have symptoms of bowel cancer, some IBD teams may ask you to complete a FIT. This can help them to decide how urgently you need a colonoscopy.

Finding out that you have bowel cancer

Treatment has the best chance of working if bowel cancer is found at an early stage. If you are at risk of developing bowel cancer you will be regularly checked. So, if you develop cancer, it’s likely to be found at an earlier stage. Nearly everyone survives bowel cancer if diagnosed at the earliest stage.

If you are diagnosed with bowel cancer, your healthcare team will talk to you about the benefits and risks of the different treatment options. The most common treatment for bowel cancer is surgery. Other treatments include chemotherapy and radiotherapy.

For more on bowel cancer diagnosis and treatments, see:

• Bowel Cancer UK
• Cancer Research UK
• Macmillan Cancer Support

These charities offer information and helpline services if you have any questions or need extra support.

Anal cancer is a rare type of cancer that develops in your anus (bottom).

Anal cancer symptoms

Some anal cancer symptoms can be like Crohn’s and Colitis symptoms. Common anal cancer symptoms include:

• Pain around or inside the bottom 
• Lumps around or inside the bottom 
• Bleeding or passing mucus from your bottom 
• Passing poo without meaning to (bowel incontinence) 
• Needing to poo more often than usual 

Recognising symptoms of anal cancer can be difficult as they can be like the symptoms of Crohn’s or Colitis. Talk to your IBD team if you notice any changes in your symptoms. It can be useful to tell them about:

• New pain around or inside the bottom
• New lumps around or inside the bottom
• Any bleeding from the bottom when you are not in a flare-up

Who is at risk

People with anal or perianal Crohn’s Disease (Crohn’s affecting the bum) have an increased risk of developing anal cancer. But the overall risk of anal cancer is very low.

Rarely, anal cancer can develop from perianal fistulas in Crohn’s Disease. Fistula-related anal cancers are more likely to develop in people:

• Who developed a fistula more than 10 years ago
• With long-term perianal disease

Anal cancer is rare. In the general population in the UK around 1,500 people are diagnosed with anal cancer each year. Of these, 9 in 10 cases are linked to human papilloma virus (HPV) infection. But the overall risk is low and most people with HPV will not get anal cancer.

See the NHS website for other risk factors for anal cancer.

Reducing your risk

There are no screening programmes for anal cancer in people with Crohn’s or Colitis because the risk is very low. If you have anal or perianal Crohn’s, speak to your IBD team as soon as possible if you notice any changes in your symptoms.

Getting the HPV vaccine is the best protection against HPV-related anal cancers. Find out more about HPV and the HPV vaccine in our information on reproductive health and fertility, or see the NHS website.

You can also find out more ways to reduce your risk of anal cancer on the NHS website.

Finding out you have anal cancer

Treatment has a better chance of working if anal cancer is diagnosed early. If you are diagnosed with anal cancer, your healthcare team will talk to you about the benefits and risks of different treatment options.

Treatments could include chemotherapy or radiotherapy, or a combination of both called chemoradiation. Sometimes surgery may be needed.

For more on anal cancer diagnosis and treatments, see:

• Cancer Research UK
• Macmillan Cancer Support

These charities offer information and helpline services if you have any questions or need extra support.

Bile duct cancer is a rare type of cancer that develops in your bile ducts. Your bile ducts are tubes that connect your gallbladder and liver to your small bowel. Bile ducts carry bile which helps to digest food.

Bile duct cancer symptoms

Bile duct cancer doesn’t always cause symptoms in the early stages. And symptoms are sometimes hard to spot. Symptoms can include:

• Yellow skin or the whites of your eyes turning yellow (jaundice)
• Itchy skin
• Pale poo and dark pee
• Tummy pain
• Feeling tired, generally unwell or feverish

Having these symptoms doesn’t mean you have bile duct cancer. But it’s important to get them checked. Speak to your IBD team if you are worried about any of your symptoms.

Who is at risk

Bile duct cancer is rare. Around 2,800 people in England are diagnosed with bile duct cancer each year.

People with Crohn’s or Colitis are at higher risk of bile duct cancer compared with the general population. Having primary sclerosing cholangitis (PSC) is also a risk factor for developing bile duct cancer. So if you have PSC and Crohn’s or Colitis your risk of developing bile duct cancer is even higher. The risk is higher in people with PSC and Colitis than with PSC and Crohn’s.

See the NHS website for other risk factors for bile duct cancer.

Reducing your risk/screening

There is no screening programme for bile duct cancer in the UK. European guidelines recommend people with both PSC and Crohn’s or Colitis have screening for bile duct cancer every 6 to 12 months. Speak to your healthcare team about whether you need regular checks. This could include blood tests and imaging, such as an ultrasound or MRI scan.

Finding out you have bile duct cancer

If you are diagnosed with bile duct cancer, your healthcare team will talk to you about the benefits and risks of the different treatment options.

You’ll be offered surgery if the cancer can be removed. You may be offered chemotherapy if the cancer can’t be removed surgically.

For more on bile duct cancer diagnosis and treatments, see:

• Cancer Research UK
• Macmillan Cancer Support
• AMMF: The Cholangiocarcinoma Charity

These charities offer information and helpline services if you have any questions or need extra support.

Small bowel cancer is a rare type of cancer. It is different to the more common bowel (colorectal) cancer, which affects the large bowel.

Small bowel cancer symptoms

Small bowel cancer symptoms can be like Crohn’s or Colitis symptoms. They include:

• Dark black poo caused by blood in your poo
• Feeling or being sick
• Unexplained weight loss
• Extreme tiredness or fatigue
• A pain or lump in your tummy
• Symptoms of a blockage in your gut, such as feeling sick, being sick and tummy pain

Recognising symptoms of small bowel cancer can be difficult as they can be like symptoms of Crohn’s or Colitis. Talk to your IBD team if you notice any changes in your symptoms.

Get medical help as soon as possible if you think you might have a blockage in your gut.

Who is at risk

People with Crohn’s have an increased risk of developing small bowel cancer. This risk is higher if:

• You have Crohn’s affecting most of your small bowel
• You have had symptoms for more than 8 years
• You have strictures or fistulas

But the overall risk of developing small bowel cancer is still low. Only around 1,800 people in the UK are diagnosed with small bowel cancer each year.

See the Cancer Research UK website for other risk factors for small bowel cancer.

Reducing your risk

There is no screening programme for small bowel cancer. It’s difficult to screen for small bowel cancer using endoscopy. Speak to your IBD team if you’re worried that you might be at risk of developing small bowel cancer.

Finding out you have small bowel cancer

If you are diagnosed with small bowel cancer, your healthcare team will talk to you about the benefits and risks of the different treatment options.

Treatments could include surgery, radiotherapy or chemotherapy.

For more information on small bowel cancer diagnosis and treatments, see:

• Cancer Research UK
• Macmillan Cancer Support

These charities offer information and helpline services if you have any questions or need extra support.

There is not much research on the effects of cancer treatments on Crohn’s or Colitis.

About a third of people (3 in every 10) starting treatment for cancer may experience a flare-up of their Crohn’s or Colitis. These flare-ups can usually be managed with steroids and biologics. Only a small number of people will need to stop their cancer treatment.

Different types of cancer treatment may affect Crohn’s or Colitis differently. Research suggests that chemotherapy and radiotherapy do not increase the risk of a flare-up. But there is not enough evidence to know for sure.

Hormone therapy or immune checkpoint inhibitor treatment may increase the risk of a flare-up. Checkpoint inhibitors are a type of immunotherapy. They block proteins that stop the immune system from attacking the cancer cells. They are also described as a type of monoclonal antibody or targeted treatment.

Your IBD team will closely monitor your Crohn’s or Colitis while having cancer treatments.

Some medicines for Crohn’s or Colitis may not be safe to take while also having cancer treatments. And for some Crohn’s or Colitis medicines, not much is known about taking them in combination with cancer treatments. Your IBD team and cancer healthcare team should discuss your individual situation and you should all come to a decision together.

We follow strict processes to make sure our information is based on up-to-date evidence and easy to understand.

Please email us at evidence@crohnsandcolitis.org.uk if:

• You have any comments or suggestions for improvements
• You would like more information about the sources of evidence we use
• You would like details of any conflicts of interest

You can also write to us at Crohn’s & Colitis UK, 1 Bishop Square, Hatfield, AL10 9NE, or contact us through our Helpline: 0300 222 5700