What is bowel cancer?

Bowel cancer is cancer in any part of the colon or rectum. This cancer can develop in two ways: it can grow from the inner lining of the bowel, or from small growths on the bowel wall called polyps. These mushroom-shaped growths are usually harmless (benign) but may become cancerous over time.

If untreated, bowel cancer can spread deeper into the wall of the bowel. From there it can spread (metastasise) to the lymph nodes (glands). Lymph nodes are small, bean-shaped masses that collect and destroy bacteria and viruses in the body. They are part of the body’s lymphatic system, which plays an important role in the functioning of the immune system. Later, bowel cancer can spread to other organs such as the liver or lungs. In most cases, it develops fairly slowly and may stay in the bowel for months or years before spreading.

What are the symptoms?

In its early stages, bowel cancer often has no noticeable symptoms. Symptoms some people experience include:

• a change in bowel habits such as appearance of stools, constipation, or smaller, more frequent bowel movements
• a feeling of fullness in the bowel or rectum
• a feeling that the bowel hasn’t emptied completely after a bowel movement
• blood in the stool or on the toilet paper
• unexplained weight loss
• weakness or fatigue
• rectal or anal pain
• feeling very tired or breathless (anaemia).

Cancer of the bowel may cause a blockage (bowel obstruction). This causes symptoms such as abdominal pain, feeling bloated, constipation and being sick. Many of the symptoms of bowel cancer are common to other large bowel conditions, such as haemorrhoids or tears in anal tissue. Some foods or medications can also change bowel habits or cause stools to turn red or black. If you have any of the above symptoms, talk to your doctor.

What causes bowel cancer?

The exact cause of bowel cancer is not known. However, some factors increase the chance of developing bowel cancer, including:

Getting older – bowel cancer more commonly affects people aged 50 and over.

Bowel diseases – people who have an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, have a significantly increased risk.

Lifestyle factors – being overweight, doing little physical activity, a diet high in fat or animal products, alcohol consumption and smoking can play a part.

Strong family history – bowel cancer can run in the family. Whether you’re at increased risk depends on who was diagnosed and at what age.

Treatment

The main treatment for bowel cancer is surgery. You may also have chemotherapy or radiotherapy. You may only need one type of treatment, but sometimes you may have a combination.

There are different types of surgery for bowel cancer. Which one you have depends on where the cancer is in the bowel, the type and size of the cancer and whether it has begun to spread? The doctor will also consider your age and general health.