Bowel cancer

Published by Bupa's Health Information Team, January 2010.

This factsheet is for people who have bowel cancer, or who would like information about it.

Bowel cancer is a lump created by an abnormal and uncontrolled growth of cells in the lining of the bowel.

How cancer develops

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About bowel cancer

Bowel cancer is the third most common cancer in the UK; around 37,000 people are diagnosed each year. It can occur at any age but is most common in people over the age of 60.

Bowel cancer, also known as colorectal cancer, is the name for any cancer of your large bowel and rectum (back passage). Very rarely, cancers can occur in your small bowel.

Your large bowel (also called your colon) is the last section of your digestive system. Food passes through your small bowel (the longer, thinner part of your bowel) where nutrients are absorbed. Food waste then travels through your large bowel, where it becomes more solid faeces.

Your large bowel has three sections: the ascending; transverse; and descending colon. Your rectum, at the end of your large bowel, is where faeces collects before passing through your anus as a bowel movement.

Usually, large bowel cancers develop from small, non-cancerous (benign) growths of tissue called polyps that can extend from the lining of your bowel wall. Sometimes polyps can become cancerous (malignant) over time. If the cancer isn't treated, it can grow through the wall of your bowel and spread to other parts of your body.

Symptoms of bowel cancer

Bowel cancer is often painless in the early stages, but there are symptoms, including:

• blood in your faeces, which may be mixed into your faeces or appear as flecks on the surface, or you may see it in the toilet or on toilet paper - get into the habit of looking into the toilet before flushing
• persistent changes in your bowel habit for several weeks - especially going to the toilet more often or having diarrhoea
• weight loss without any obvious reason and/or loss of appetite
• tiredness or breathlessness for no apparent reason - this may be caused by the small amount of blood loss from your bowel, resulting in anaemia (when there are too few red blood cells or not enough haemoglobin in your blood)
• pain, or a lump or swelling in your abdomen (tummy)

These symptoms aren't always due to bowel cancer. However the symptoms shouldn't be ignored so if you have them, see your GP. If bowel cancer is caught early there is a better chance of curing it.

Causes of bowel cancer

The causes of bowel cancer aren't fully understood at present. One of the main factors is increasing age - more than eight out of 10 people diagnosed with bowel cancer are over 60.

Your risk of bowel cancer also increases if you have:

• a family history of bowel cancer
• one of two inherited bowel conditions that increase your risk - familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome
• a long-term bowel condition, such as Crohn's disease or ulcerative colitis
• a diet that is low in fibre and fruit and vegetables and high in red and processed meats
• an inactive lifestyle, or are obese
• diabetes

Diagnosis of bowel cancer

Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history. Your GP may refer you to a doctor or surgeon who specialises in colorectal disease.

Tests for bowel cancer include the following.

• A colonoscopy, which is a test that allows a doctor to look inside your large bowel. The test is done using a narrow, flexible, tube-like telescopic camera called a colonoscope.
• A sigmoidoscopy, which is a procedure used to look inside your rectum and the lower part of your bowel.
• A barium enema, which involves placing a fluid containing barium (a substance which shows up on X-rays) into your bowel via your rectum. X-ray images of your abdomen then show the inside of your bowel more clearly.

If your doctor diagnoses bowel cancer, you may need further tests to find the size and position of the cancer.

These tests may include:

• an ultrasound scan of your abdomen to see if the cancer has spread
• a CT scan to show the position of the tumour
• an MRI scan to show two- and three-dimensional pictures of your bowel
• a chest X-ray to check the health of your heart and lungs
• blood tests to assess your general health

Screening for bowel cancer

Screening is important for detecting bowel cancer in its early stages. The Department of Health has introduced a bowel cancer screening programme in England. Bowel cancer screening kits are sent to men and women aged between 60 and 69, although if you're older you can also request a kit. There are different programmes running in the rest of the UK. Ask your GP whether the screening programme has started in your area.

The screening kit contains a faecal occult blood (FOB) test that can detect small amounts of blood in your faeces. The FOB test doesn't diagnose bowel cancer, but the results show if you need to have your bowel examined.

You may choose to have regular screening if you:

• are over 60 years old
• have a close relative who has had bowel cancer
• have FAP, HNPCC, or other diseases of the bowel lining such as ulcerative colitis or Crohn's disease

Treatment of bowel cancer

The type of treatment you have will depend on the size of the tumour, its position and whether it has spread.

Surgery

Surgery is the most common treatment for bowel cancer.

If you have surgery, the part of your large bowel that contains the cancer will be removed and the two open ends joined together. Lymph nodes (glands found throughout your body that are part of your immune system) near your bowel are often removed because they are the first place the cancer usually spreads to.

Sometimes, depending on the location and size of the cancer that is removed, the two ends of your bowel can't be rejoined. If this happens, the opening nearest the beginning of your bowel will be brought out on to the skin surface of your abdomen. A colostomy is an opening of your large bowel onto the surface of your tummy (abdomen) and an ileostomy is an opening of your small bowel onto the surface of the abdomen. The opening of the bowel is known as a stoma.

A bag is worn over the stoma, which collects your bowel movements outside your body. Most people who have surgery don't need a colostomy, but if you do, it's usually temporary.

If you have cancer in your rectum, you may need surgery to remove the part of your rectum that contains the cancer, as well as the fatty tissue and lymph nodes around your rectum. You're more likely to need a colostomy if you have cancer of the rectum than if you have cancer of the colon.

Non-surgical treatments

Chemotherapy and radiotherapy
Sometimes it's not possible to remove all the cancer by surgery, so you may need to have additional treatment with chemotherapy and/or radiotherapy.

These treatments are given to destroy any remaining cancer cells and to prevent it spreading further. Chemotherapy and radiotherapy are also sometimes used to shrink the tumour before surgery or to kill any cancer cells that are left after surgery.

Chemotherapy and radiotherapy can both have side-effects.

Monoclonal antibodies
Monoclonal antibodies (MABs) are medicines that are designed to recognise and target markers that are commonly carried by cancer cells. There are three main MAB treatments for bowel cancer:

• bevacizumab
• cetuximab
• panitumumab

These medicines seek out cancer cells and stop them growing. They are sometimes used alongside chemotherapy. They can be used for various stages of cancer - ask your doctor for more advice.

Prevention of bowel cancer

There is evidence that taking the following steps can help to reduce your risk of getting bowel cancer.

• Try to do 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more. You can do this by carrying out 30 minutes on at least five days each week. Alternatively, you can do 75 minutes of vigorous intensity activity.
• Eat five or more portions of fruit and vegetables every day.
• Cut down on the amount of processed and red meat you eat.
• Maintain a healthy weight.
• Eat foods high in fibre such as wholegrain bread, cereals and pasta.
• If you smoke, quit.

Getting enough vitamin D may reduce your risk of developing a number of cancers, including bowel cancer – although more research needs to be done to be certain. Vitamin D is also well known to be important for bone health.

Vitamin D is produced naturally by your body when your skin is exposed to sunlight and can also be obtained from some foods, such as oily fish. You may get enough vitamin D during summer by spending frequent short spells in the sun without wearing sunscreen (the exact time you need is different for everyone, but is typically only a few minutes in the middle of the day). However, do not let your skin redden. If you don't get much sun exposure and particularly during winter months, taking up to 25 micrograms of vitamin D a day (two high-strength 12.5 microgram capsules) can help to make sure you get enough.

Always read the patient information leaflet that comes with your supplements and if you are pregnant or breastfeeding, ask your pharmacist or GP for advice first. Talk to your GP before taking vitamin D supplements if you are taking diuretics for high blood pressure or have a history of kidney stones or kidney failure.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.