Bowel cancer

Last updated:

Reviewed by:

Dr Bryony Henderson

, Lead GP at Livi

Medically reviewed

Bowel cancer occurs when malignant (or cancerous) tissue, known as a tumour, grows in the lining of the bowel. A tumour can develop in different parts of the bowel and, depending on its location, can also be termed colon or rectal cancer.

What is bowel cancer?

The bowel is essentially the lower half of your digestive tract (defined as being below the level of the stomach) and is made up of your small and large intestine, rectum and anus. A tumour can develop anywhere along the tract, however cancer of the rectum  is the most common. 

Bowel cancer is the fourth most prevalent cancer in the UK, behind breast, prostate and lung cancer.

  • Age – 40% of bowel cancer cases every year  are diagnosed in those older than 75

  • Weight – Having a BMI above 30 (obese) and a BMI between 25 and 30 (overweight) is a known risk factor for developing bowel cancer

  • Diet – a high red and processed meats diet as well as a low-fibre diet has been shown to increase risk.

  • Smoking and alcohol – drinking or smoking can increase your chances of bowel cancer. 

  • Family history – having a first-degree relative (parent, sibling or child) who has developed bowel cancer under the age of 50 puts you at a greater risk of developing the condition in your lifetime. The risk is greater if you have more than one first degree relative with bowel cancer or if the diagnosis was at a young age. 

Screening is available in some circumstances to people with a family history of bowel cancer.

How can I reduce my chances of getting bowel cancer?

While you have no control over things like your age and family history, there are steps you can take to reduce your risk of developing bowel cancer: 

  • Eat a healthy, balanced diet that contains enough fibre and low amounts of processed and red meat

  • Reduce your weekly alcohol intake 

  • Stop smoking or try nicotine-replacement therapy

  • Become more active and try to lose weight if you’re overweight

Bowel cancer symptoms

The symptoms may vary slightly depending on the exact location of the cancer but there are four main symptoms to look out for. These include: 

  • Change in bowel habit – usually an increase in the frequency and the runniness of the poo

  • Blood in your poo – that is associated with no particular reason or occurs with a change in bowel habit

  • Persistent lower stomach pain, bloating or discomfort – this will occur with eating and may be associated with appetite or significant unintentional weight loss

  • Unexplained weight loss – if you find you have lost weight despite your diet remaining the same

It’s important to note that most people that experience the symptoms above will not have bowel cancer. Instead things like medication, diet or haemorrhoids are more likely causes.

When to speak to a GP

You should seek medical advice if you have had any bowel cancer  symptoms for 3 weeks or more.

Your GP will discuss your symptoms with you before arranging, if necessary, further investigation.

How is bowel cancer diagnosed?

Your GP will spend time talking to you about your symptoms. 

  • Physical examination – your GP will usually examine your tummy and bottom to assess for any obvious lumps. This is called a digital rectal exam (DRE) and can be helpful in determining whether there is anything in the rectum that could be causing your symptoms. 

  • Blood test – if necessary, a blood test will be requested by your GP to test for iron deficiency anaemia. 

  • Stool test – Your GP may ask you for a stool sample so that the laboratory can look for small amounts of blood.

Your GP may, on talking to you and investigating, refer you for further investigation and testing. This can include:

  • Colonoscopy/sigmoidoscopy – this involves a thin, flexible tube with a camera being passed through your back passage and into your bowel. A biopsy can also be taken during the procedure. It’s better for your bowel to be empty prior to these tests so you may be asked to take some medicine before the procedure.

  • CT colonography – sometimes a colonoscopy may not be suitable and this investigation may be used instead. A tube does need to be placed in the rectum to gently inflate the bowel but it is not as invasive as a colonoscopy. 

Bowel cancer screening 

If you’re aged between 60 and 74 (and those aged 56) you will be invited to participate in the NHS screening programme for bowel cancer. The earlier a cancer is found the easier it is to treat and the purpose of the screening programme is to try and identify bowel cancer early and before symptoms start. 

The screening test consists of a home test kit which is used to collect a sample of poo. It is then sent to a lab where it will be checked for any traces of blood. 

It’s important that you talk to your doctor if you’re worried that you have bowel cancer instead of waiting for the screening programme. 

In some circumstances, your doctor might recommend regular screening if you have a strong family history of bowel cancer. If you have a first degree relative diagnosed with bowel cancer under the age of 50 (or more than two relatives diagnosed at any age) or if one of your relatives has been diagnosed with a genetic condition that increases the risk of bowel cancer, then it is important to make your healthcare provider aware. 

How is bowel cancer treated?

After a diagnosis of bowel cancer is made, the best treatment options are discussed by a group of oncologists, surgeons and other health professionals to agree on the most appropriate management options. The options include: 

  • Surgery - the part of the bowel containing the tumour is removed through either  keyhole, robotic or open surgery. Sometimes only a small amount needs to be removed but, on other occasions, a colectomy (removal of a section of colon) might be needed. 

  • Chemotherapy - where medication is used to kill cancer cells 

  • Radiotherapy - when radiation is used to kill cancer cells 

  • Targeted therapies - a newer group of medicines that target specific ways the cancer uses to spread They can help increases the effectiveness of chemotherapy

Treatment for bowel cancer changes from patient to patient and will depend on where the cancer is in the bowel as well as how far the cancer has spread). 

What is the prognosis for bowel cancer?

When a patient is diagnosed with bowel cancer, the cancer is ‘staged’. This tells doctors how large the cancer is, where it is and whether it has spread. Information from all the investigations and any surgery help determine this stage. The stages are given numbers with ‘stage 1’ telling us that the cancer has not spread beyond the bowel wall to ‘stage 4’ telling us that the cancer has spread beyond the bowel wall and lymph nodes. 

The prognosis of bowel cancer varies depending on the stage. 

Stage 1 - 90% of people will survive for 5+ years

Stage 2 - 80% of people will survive for 5+ years

Stage 3 - 70% of people will survive for 5+ years

Stage 4 - 10% of people will survive for 5+ years

Last updated:
Reviewed by:
Dr Bryony Henderson, Lead GP at Livi