About bowel cancer

What is bowel cancer?

Bowel cancer (also called colorectal cancer) is cancer in any part of the large bowel (colon or rectum). It may also be called colon cancer or rectal cancer, depending on where in the bowel it is.

The cancer starts in the lining of the inner bowel wall (called the mucosa). It usually develops from small growths called polyps. Most polyps are harmless (benign), but some may turn into cancer. Removing polyps during a colonoscopy reduces the risk of bowel cancer.

If untreated, bowel cancer can grow into the deeper layers of the bowel wall. It can also spread to the lymph nodes. If the cancer advances further, it can spread to other organs, such as the liver or the lungs.

How common is bowel cancer?

Bowel cancer is the 4th most common cancer in Australia. Each year, about 15,500 Australians are diagnosed with bowel cancer. It is more common in people over 50, but it can happen at any age. The number of adults under 50 with bowel cancer is increasing, with research yet to give a clear reason for this.

Less common types of bowel cancer

Most bowel cancers are adenocarcinomas, which start in the tissue lining the large bowel. Rarely, other less common types of cancer can also affect the bowel. These include lymphomas, squamous cell carcinomas, neuroendocrine tumours and gastrointestinal stromal tumours. Cancer can also start in the small bowel (called small bowel cancer or small intestine cancer), or in the appendix, but this is rare. These cancers are not included in this section, and may have different treatment.

For more information about these less common types of bowel cancers, call Cancer Connect on 13 11 20.

The bowel

The bowel is part of the lower gastrointestinal (GI) tract, which is part of the digestive system. The digestive system starts at the mouth and ends at the anus. It helps the body break down food and turn it into energy. It also gets rid of the parts of food the body does not use.

The small bowel (also called small intestine)

This is a long tube (4–6 m) that absorbs nutrients from food. The small bowel is longer and narrower than the large bowel.

It has 3 parts:

• duodenum – top section; receives broken-down food from stomach
• jejunum – middle section
• ileum – lower, longest section; moves waste to large bowel.

The large bowel (also called large intestine or colon)

About 1.5 m long, this tube absorbs water and salts, and turns what is left into solid waste (faeces, stools or poo).

The large bowel has 3 parts:

• caecum – looks like a pouch; it receives waste from the small bowel; the appendix is attached to the caecum 
• colon – main, longest section of the large bowel; has 4 parts: ascending colon, transverse colon, descending colon and sigmoid colon
• rectum – the last 15–20 cm of the large bowel. 

This bowel cancer information is only about cancer of the large bowel.

The anus

This is the opening at the end of the large bowel. During a bowel movement, the anal muscles relax to release faeces (poo).

For more information, see Anal cancer.

The lower digestive system

Which health professionals will I see?

Your general practitioner (GP) will arrange the first tests to assess your symptoms, or further tests if you have had a positive screening test. If these tests do not rule out cancer, you will usually be referred to a specialist, such as a gastroenterologist or colorectal surgeon.

The specialist will arrange further tests. If bowel cancer is diagnosed, the specialist will consider treatment options. Often these will be discussed with other health professionals at what is known as a multidisciplinary team (MDT) meeting. During and after treatment, you may see a range of health professionals who specialise in different aspects of your care.

Health professionals you may see

• GP – assists you with treatment decisions and works in partnership with your specialists in providing ongoing care
• colorectal surgeon – diagnoses bowel cancer; performs bowel surgery; may perform colonoscopy
• gastroenterologist – diagnoses and treats disorders of the digestive system, including removing bowel polyps; performs colonoscopy
• radiation oncologist, radiation therapist – a radiation oncologist treats cancer by prescribing and overseeing a course of radiation therapy; a radiation therapist plans and delivers radiation therapy
• medical oncologist – treats cancer with drug therapies such as chemotherapy, targeted therapy and immunotherapy (systemic treatment)
• cancer care coordinator – coordinates your care, liaises with other members of the MDT, and supports you and your family throughout treatment; care may also be coordinated by a clinical nurse consultant (CNC), cancer nurse specialist or colorectal cancer nurse, or patient navigator
• nurse – administers drugs and provides care, information and support throughout treatment
• stomal therapy nurse – provides information about surgery and can help you to adjust to life with a temporary or permanent stoma
• dietitian – helps with nutrition concerns, weight issues and suggests diet changes during treatment and recovery
• genetic counsellor – provides advice for people with a strong family history of bowel cancer or with a genetic condition linked to bowel cancer
• social worker – links you to support services and helps you with emotional, practical and financial issues
• physiotherapist, exercise physiologist – help restore movement and mobility, and improve fitness and wellbeing
• continence physiotherapist – provides exercises to help your pelvic floor muscles recover and improve bowel and bladder control
• occupational therapist – assists in adapting your living and working environment to help you resume usual activities after treatment
• counsellor, psychologist – help you manage your emotional response to diagnosis and treatment
• palliative care specialist and nurses – work closely with the GP and cancer team to help control symptoms and maintain quality of life