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For Bowel Cancer Awareness Month, Dr Siwan Thomas-Gibson discusses the disease and the importance of screening.

About Professor Siwan Thomas-Gibson

Professor Siwan Thomas-Gibson is a gastroenterologist and specialist endoscopist at St Mark’s National Bowel Hospital London. She is the Dean of St Mark’s Hospital Academic Institute and Professor of Practice in Gastrointestinal Endoscopy at Imperial College London.
View Professor Siwan Thomas-Gibson’s full profile

What is bowel cancer? 

Bowel cancer refers to a cancerous growth in either the large bowel, also known as the colon, or the rectum, which is at the very end of the bowel. 

Man suffering stomach pain

What are the common symptoms of bowel cancer? 

Unfortunately, bowel cancer often doesn’t present with symptoms until a very late stage. However some of the common symptoms to look out for are: 

  • Blood in your stools. If the cancer is low down in the bowel, you may see blood in your stool or bleeding from your bottom
  • If you have a bowel cancer higher up in the bowel, you may not see bright red blood in your stool, but your bleeding from it may cause symptoms of anaemia for example breathlessness, feeling fatigued and tired
  • A persistent change in your bowel habit. For instance if you start going to the toilet with increased frequency or erratically over a number of weeks with no other obvious cause
  • When a growth is blocking or obstructing the bowel you may get tummy pain, bloating or discomfort
  • Some people may even feel a lump in their abdomen. 

Many of the symptoms of colorectal cancer can also be caused by something that isn’t cancer, such as infection, haemorrhoids, or inflammatory bowel disease. However, if you have any of these persistent symptoms, no matter what your age, you should go and speak to your GP who can refer you to rule out cancer or other problems. 

How common is bowel cancer?

Bowel cancer is the fourth most common cancer in the UK, with around 41,000 people diagnosed every year. According to Bowel Cancer UK, 1 in 14 men and 1 in 19 women will be diagnosed with bowel cancer in their lifetime.  

Why do you think that is? 

It is not exactly clear what causes bowel cancer but there are a number of factors that can increase the risk:

  • Bowel cancer is a disease of aging, usually affecting people over the age of 50 and gets more common with increasing age. Almost 90% of bowel cancers are diagnosed in people over the age of 50. However, that does mean that over 10% of cases affect people under the age of 50
  • Smoking and drinking alcohol in excess 
  • Being overweight or obese
  • A diet high in red or processed meats and not enough fibre from fruit and vegetables 
  • Some conditions greatly increase your risk of bowel cancer, including: Lynch syndrome, Familial adenomatous polyposis, Inflammatory bowel disease (Crohn’s disease or Ulcerative colitis). 

If there is a history of bowel cancer in the family, should extra precaution be taken? 

Be aware of your family history. If a close relative, say your mother, father, brother or sister, developed bowel cancer under the age of 50 this may put you at greater risk of developing the condition, particularly if more than one close relative has been affected. You should discuss this with your GP, who will assess your individual risk. 

If you have an elderly grandparent who developed bowel cancer at an advanced age, this is not cause for concern and does not put you at increased risk. 

How do you check for bowel cancer? 

There are a number of screening methods that can detect bowel cancer, this includes:

Stool tests, the most popular being a faecal occult blood (FOB) test. This involves screening a stool sample for hidden blood, as polyps and cancers tend to bleed. Bowel polyps are small growths on the inner lining of the large bowel or rectum. Some types of polyps, called adenomas, may become cancerous over time. 

If you are anaemic with no good explanation, or have blood in your stool, your GP should refer you to see a gastroenterologist or colorectal surgeon to do further investigations. They would probably recommend one of two tests: 

  1. Colonoscopy
    A colonoscopy is a flexible camera examination of the full length of the large bowel. Before the procedure the bowel is prepared with strong laxatives to empty it. Some people choose to have a colonoscopy without any sedation, but around 60 to 70% will want a light sedative for this procedure as it can be slightly uncomfortable. A colonoscopy is done as a day case and only requires you to be in hospital for a couple of hours. If you have sedation it is important you have someone to accompany you home. 

    One advantage of a colonoscopy is that if any polyps or pre-cancerous growths are found, they can usually be removed at the time of procedure. These will then be sent to our on-site laboratory to ensure the polyp has been completely removed and if there is any cancerous change in it.  
  2. CT colonography
    A CT colonography involves inserting a thin tube into the very end of the bowel, which pumps gas inside. X-ray images of the bowel are taken. If this is completely normal and clear you do not have bowel cancer. But if a pre-cancerous polyp or other abnormality is detected, a colonoscopy or sigmoidoscopy (a limited camera examination of the lower part of the bowel) is required to remove the polyps or to take biopsies.  

What are the treatment options? 

Polyps and pre-cancerous growths are commonly removed during a colonoscopy. If the polyps are very large or there is a lot of them throughout the bowel surgery may be required, but this is rare.

If you are diagnosed with bowel cancer you will have a series of other diagnostic tests, including CT scans. This will distinguish where the cancer is and if it has spread outside of the bowel to other organs such as the lung, liver or lymph glands.

If the cancer has not spread outside the bowel, surgery is the most effective way of curing the cancer. It involves removing part of the bowel or rectum where the cancer is located. Often the bowel can be joined together. This can often be done via keyhole and sometimes by robotic surgery. If the cancer has spread outside the bowel you may need chemotherapy.

Some people also have radiotherapy, especially those who have rectal cancers and for advanced bowel cancers. The London Clinic is the first private hospital to use colorectal intraoperative radiotherapy (IORT).

Your cancer surgeon will discuss your diagnosis and treatment options with an oncologist at a multidisciplinary team meeting to decide the best package of care for you. 

How effective is treatment? 

If bowel cancer is caught early and it is confined to the bowel wall then your surgery is curative, with good survival rates. 

There are different stages of bowel cancers, stage one to four. Stage one means the cancer is only in the bowel and stage four means it has spread outside of the bowel to the surrounding organs. 

Your chances of survival are better the earlier the cancer is found, which is why there is a real need for screening procedures, that is to say tests to look at the bowel before someone has symptoms. In the UK in the NHS that starts at age 55. 

What happens after treatment? 

Following treatment you will need to be put on a surveillance programme as there is an increased risk of developing bowel cancer and polyps in the remaining bowel. Your surgeon or gastroenterologist will manage this process. 

A gastroenterologist can also help you with the consequences of cancer treatment. Following surgery, chemotherapy or radiotherapy some bowel cancer patients may end up with a shorter bowel or rectum which can cause pain, less control of bowel habits and bleeding.

These symptoms aren’t often talked about before or during treatment and even if they are, often the patient’s focus is on the immediate treatment of the cancer.

At The London Clinic, we have specialist gastroenterologists, nurses and dieticians who can support patients with any symptoms that arise as a consequence of cancer treatment. 

What has the biggest impact in diagnosing and treating bowel cancer? 

Bowel cancer screening has definitely been shown to have the biggest impact in saving lives.

To prevent your risk of developing bowel cancer; don’t smoke, don’t drink alcohol in excess, stay at a healthy weight through exercise and healthy eating. Avoid eating processed foods and red meat but do eat lots of fruit and vegetables. 

My one key message to take away is, if you have bleeding from your bottom that hasn’t been investigated, you need to see a consultant to rule out bowel cancer. 

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