What is rectal cancer?

Clinical Oncologist Katherine Aitkens explains bowel cancer (which includes rectal cancer), giving an overview of bowel cancer symptoms, diagnosis and treatment.


The rectum is part of the large bowel, which is part of the digestive system. Rectal cancer is more common in older people. In the UK, almost 6 in 10 bowel cancer cases (58%) each year are diagnosed in people aged 70 and over.

We have more information about other types of bowel cancer including:

Related pages

Booklets and resources

Symptoms of rectal cancer

Some people may start by seeing their GP because they have symptoms. Symptoms of rectal cancer can include:

  • blood in your poo (stools)
  • bleeding from the back passage
  • a change in your normal bowel habit.

If you are worried about rectal cancer, we have more information about bowel cancer symptoms.

Other people may be diagnosed by:

  • Having NHS Bowel Screening

    Bowel screening is a way of finding bowel cancer at an early stage before it causes symptoms.

  • Going to hospital with a problem, such as bowel obstruction

    This is when part of the bowel becomes blocked. It may cause symptoms such as tummy pain, nausea and vomiting, and constipation.

If you have any symptoms or notice anything that is unusual for you, you should see your GP straight away.

Related pages

Causes of rectal cancer

The exact cause of colorectal cancer (colon or rectal cancer) is unknown. But, things called risk factors can increase the chance of a person developing it. Having one or more risk factors does not mean you will definitely get rectal cancer. And if you do not have any risk factors, it does not mean you will not get rectal cancer.

Diagnosis of rectal cancer

If you have symptoms, you will usually begin by seeing your GP, who will examine you. If they think that your symptoms could be caused by cancer, they will refer you to a specialist doctor.

At the hospital

The doctor will ask you about your general health and any previous medical problems you have had. They will also ask whether you have a family history of bowel cancer.

The doctor will examine you and you will usually also have one of the following tests:

  • Rectal examination

    A rectal examination is when the doctor places a gloved finger into your back passage to feel for any lumps or swelling.

  • Blood test

    You usually have a blood test to check your level of red blood cells. If you have a low number of red blood cells, this is called anaemia. You will also have blood tests to check if your liver and kidneys are working normally.

You may also have some of the following tests:

  • Colonoscopy

    A colonoscopy looks at the inside of the whole length of the large bowel. You can usually have this test as an outpatient. It takes about an hour.

  • Virtual colonoscopy

    In a virtual colonoscopy, a computerised tomography (CT) scanner takes a series of x-rays. This builds up a three-dimensional picture of your bowel.

  • Sigmoidoscopy

    A sigmoidoscopy looks at the inside of the rectum and the part of the colon closest to the rectum (the sigmoid colon). You can usually have it as an outpatient.

Waiting for tests can be a difficult time, we have more information that can help.

Further tests for rectal cancer

If any of your biopsies show that there is cancer in the rectum, you will have more tests. The results will help you and your doctor decide on the best treatment for you. Some tests may be repeated during and after treatment. You may have any of the following tests:

  • More blood tests

    Your blood may be tested for a protein called carcinoembryonic antigen (CEA). Some people with bowel cancer have higher levels of this protein.

  • CT scan

    A CT (computerised tomography) scan uses x-rays to build a three-dimensional (3D) picture of the inside of the body.

  • MRI (magnetic resonance imaging) scan

    An MRI scan uses magnetism to build up a detailed picture of areas of your body.

  • Endorectal ultrasound scan (ERUS)

    An endorectal ultrasound scan (ERUS) can show the size and location of a cancer in the rectum, using sound waves to build up a picture. This test may be used to help plan your operation.

  • PET-CT scan

    A PET-CT scan is a combination of a CT scan, which takes a series of x-rays to build up a three-dimensional picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

Staging and grading of rectal cancer

The results of your tests help your doctors find out more about the size and position of the cancer and whether it has spread. This is called staging.

A doctor decides the grade of the cancer by how the cancer cells look under the microscope. This gives an idea of how quickly the cancer might grow or spread.

Knowing the stage and grade helps your doctors plan the best treatment for you.

Treatment for rectal cancer

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your doctor will explain the different treatments and their side effects. They will also talk to you about the things you should consider when making treatment decisions.

Surgery is the most common treatment for rectal cancer. But the treatment you have depends on the stage of the cancer and where it is in the rectum. It also depends on your general health and preferences. Find out more about treatment options for rectal cancer.

Treatment may include:

  • Surgery

    Surgery is often used to remove cancer or areas affected by the cancer. It may also be used to help control symptoms

  • Chemotherapy

    Chemotherapy uses anti-cancer drugs to destroy cancer cells. You may have it before or after surgery. It may be given as as the main treatment if the cancer has spread.

  • Radiotherapy

    Radiotherapy is the use of high-energy rays, usually x-rays and similar rays (such as electrons) to treat cancer. It is sometimes given before surgery to shrink the cancer or it may be used to control symptoms.

  • Chemoradiation

    Chemoradiation is a combination of chemotherapy and radiotherapy. It is also sometimes called chemoradiotherapy.

  • Targeted therapies

    Targeted therapy drugs target something in or around a cancer cell that is helping it grow and survive. Targeted therapies are sometimes used to treat bowel cancers (colon or rectal) that have spread to other parts of the body.

You may also have some treatments as part of a clinical trial.

Most people have changes in how their bowel works after treatment for rectal cancer. These effects usually improve over time. We have more information about managing bowel changes caused by treatment.

After treatment for rectal cancer


The aim of follow-up care is to make sure everything is going well and to find out if you have any concerns. The appointments are usually every few months in the first year.

We have more information on follow-up care after treatment.

You may get anxious between appointments. This is natural. It may help to get support from family, friends or a support organisation. 

Macmillan is also here to support you. If you would like to talk, you can: 

Sex life

Rectal cancer and its treatment can affect your sex life. Changes may get better over time, but sometimes they are permanent. If you have any problems or are worried about this talk to your doctor or nurse. They can explain what to expect and there are often things that can help.


Some cancer treatments can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Well-being and recovery

Even if you already have a healthy lifestyle, you may choose to make some positive lifestyle changes after treatment. Making small changes such as eating well and keeping active can improve your health and well-being and help your body recover.

Related pages

About our information

  • References

    Below is a sample of the sources used in our rectal cancer information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    R Glynne-Jones, PJ Nilson, C Aschele et al. ESMO-ESSO-ESTRO Clinical practice guidelines for diagnosis, treatment and follow up for anal cancer. July 2014. European Society of Medical Oncology. Available from www.esmo.org/Guidelines/Gastrointestinal-Cancers/Anal-Cancer (accessed October 2019).

    National Institute for Health and Excellence (NICE). Colorectal cancer: diagnosis and management clinical guidelines. Updated December 2014. Available from www.nice.org.uk/guidance/cg131 (accessed October 2019).

    Association of Coloproctology of Great Britain & Ireland (ACPGBI). Volume 19. Issue S1. Guidelines for the management of cancer of the colon, rectum and anus. 2017. Available from www.onlinelibrary.wiley.com/toc/14631318/19/S1 (accessed October 2019).

    National Institute for Health and Care Excellence. Preoperative high dose rate brachytherapy for rectal cancer. 2015. Available from www.nice.org.uk/guidance/ipg531 (accessed October 2019).

    BMJ. Best practice colorectal cancer. Updated 2018. Available from www.bestpractice.bmj.com/topics/en-gb/258 (accessed October 2019).

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 30 April 2020
Next review: 30 April 2023

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.