What is bowel cancer?

Bowel cancer (also known as rectal, colorectal or colon cancer) affects the lower part of the digestive system – the large bowel and the rectum.

The condition is rare in people under 40 and almost 85 per cent of cases are diagnosed in over 65-year-olds. It affects men and women equally, and is the third most common type of cancer in men and the second most common in women. One in 20 people in the UK develops bowel cancer.

Bowel cancer isn’t easy to treat, mainly because it’s often detected once well-established – and possibly after it has spread beyond the bowel. However, estimates suggest that nine out of 10 cases can be successfully treated if detected early. Survival has doubled over the past 30 years because of early diagnosis.

Doctors urge the public to be more aware of the warning signs of bowel problems and to report them promptly.

Bowel cancer symptoms

The problem with bowel cancer symptoms is that they could easily be caused by less life-threatening complaints, such as haemorrhoids  or Irritable bowel syndrome .

However, doctors advise that if the following symptoms persist for longer than a couple of weeks, medical attention should be sought:

  • Blood flecks in your stools, particularly if the blood is dark or plum-coloured – this is the most commonly noticed symptom and should never be ignored
  • A change in your regular bowel habits, such as constipation or diarrhoea, that’s severe or lasts for two weeks or more
  • A feeling that you need to empty your bowels even when you’ve just been to the toilet
  • Abdominal pain or discomfort that lasts for two weeks or more
  • Unexplained weight loss
  • Some people feel tired, dizzy or breathless because they’ve become anaemic from microscopic bleeding from the bowel

Bowel cancer causes

The exact cause of bowel cancer isn’t known, but there is believed to be a genetic link to a small number of cases, as those with a family history are more likely to develop it themselves.

If you have a first-degree relative (a member of your immediate family) diagnosed before the age of 45 or two immediate family members affected by the condition, you should talk to your GP about genetic screening to see if you’re at risk. Keep a record of your family health history.

Diet is also a key factor identified by scientists. Low-fibre, high-fat diets are thought to have increased the rates of bowel cancer.

Your risk of bowel cancer increases with age, as the average age of diagnosis is about 70. However, younger people can also be diagnosed with the disease. Previous problems with chronic inflammatory bowel disease, such as long standing ulcerative colitis and Crohn’s disease, also appear to increase the risk.

Diagnosing bowel cancer

To diagnose bowel cancer, your GP may do a rectal examination to check for any abnormal changes. This involves putting a gloved finger in the rectum to feel for any lumps or swellings – this is usually only slightly uncomfortable.

The NHS Bowel Cancer Screening Programme was introduced in 2006. It offers routine screening every two years to all men and women aged 60 to 69

To investigate bowel cancer symptoms, doctors and hospital specialists often ask patients to undergo sigmoidoscopy or colonoscopy. Both involve gently pushing a long thin tube containing a tiny video camera through your back passage and into the rectum and colon to take a close look at the inside of the bowel. If polyps or abnormal areas of the lining of the bowel are seen, biopsies may be taken and sent to the laboratory for analysis. This can be uncomfortable, but is very seldom a painful experience.

A barium enema may also be done. This involves injecting a dye into the lower bowel via an enema, which shows up on x-rays to help doctors spot signs of cancers.

If the diagnosis is cancer, the tumour will then be staged. Doctors may order more complex tests such as CT or MRI scans to see if the cancer has spread to other organs, such as the liver. This helps doctors to work out what treatment is most appropriate and to provide an estimate of the chances of a cure.

Bowel cancer treatments

The main treatment option for bowel cancer is surgery  – if the disease can be caught before it breaks through the bowel wall, chances of success are much higher.

Usually, the piece of bowel that contains the cancer is removed and the two open ends are joined back together. This operation is called a bowel resection.

If the two sections can’t be joined back together, often because the tumour is too low, the bowel can be brought out through the abdominal wall. This is called a stoma, which is connected to a colostomy bag. Although this procedure is more likely after removal of a tumour in the rectum, it isn’t always necessary and may only be temporary. In these cases, further treatment may not be necessary.

Chemotherapy  and radiotherapy  are increasingly being used to treat bowel cancer in addition to surgery, especially in more advanced tumours. For example, a combination of radiotherapy and chemotherapy may be given before surgery for rectal cancer. This is known as neo-adjuvant therapy and may reduce the risk of recurrence and improve survival rates.

How well patients do after treatment depends on the stage the cancer has reached. Survival rates have improved in the past 30 years, but overall survival is still only about 50 per cent at five years. However, when bowel cancer is caught early – before it has spread to other organs such as the liver or the lungs – the chances of recovery are more than 80 per cent.

Preventing bowel cancer

People are encouraged to eat plenty of fresh fruit and vegetables, as this appears to reduce the risk. A high-fibre diet with plenty of fruit, vegetables and carbohydrates (pasta, bread, rice) is believed to reduce the risk of colorectal cancer. Moderate amounts of exercise may also protect against bowel cancer.

Eating a diet high in saturated fat and red meat, and low in fibre, smoking and being overweight, increases your risk as does drinking excessive amounts of alcohol.

Eating at least five portions of fruit and vegetables every day is thought to protect against this and many different cancers through the benefits of the antioxidant vitamins and minerals they contain.

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