Bowel cancer

What is bowel cancer?

Bowel cancer is the fourth most common cancer affecting Australians. It is estimated around 15,500 people are diagnosed with bowel cancer every year. It is most common in people over 50, but it can occur at any age.

In its early stages, bowel cancer may have no symptoms, but if detected early, it can be successfully treated.

A lot can happen in a hurry when you’re diagnosed with cancer. The guide to best cancer care for bowel cancer can help you make sense of what should happen. It will help you with what questions to ask your health professionals to make sure you receive the best care at every step.

How bowel cancer develops

The caecum, colon and rectum together are known as the large bowel. Bowel cancer usually affects the large bowel. Cancer of the large bowel is also known as colorectal cancer and might be called colon cancer or rectal cancer, depending on where it starts in the bowel.

Small bowel cancer is a rare type of cancer.

Illustration above adapted from original illustration, courtesy of the Cancer Council Victoria.

The bowel 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 large bowel is a roughly 1.5m long ‘tube’ that absorbs water and salts, and turns what is left into solid waste (faeces, stools or poo).

The development of bowel cancer starts in the inner lining of the bowel wall. 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.

Bowel cancer usually develops from small growths called polyps. Most polyps are harmless (benign), but some may turn into cancer. To prevent this, polyps can be removed during a colonoscopy.

Symptoms of bowel cancer

Some people have no symptoms and the cancer is found through screening. However, many people with bowel cancer experience some of the symptoms listed below. Symptoms may include:

• blood in or on faeces (poo) or on the toilet paper; this might be bright red or make the poo look dark brown or black
• a persistent or unexplained change in bowel habits, such as diarrhoea or loose stools, constipation or smaller, more frequent bowel movements
• a change in the look of faeces (e.g. narrower or with mucus)
• a feeling of fullness or bloating in the abdomen (belly) or a strange sensation in the rectum, often during a bowel movement
• a feeling that the bowel hasn’t emptied completely after you have done a poo
• losing weight without trying to
• rectal or anal pain
• a lump in the rectum or anus
• abdominal pain or swelling
• weakness or fatigue, dizziness or breathlessness
• a low red blood cell count (anaemia or iron deficiency)
• a blockage in the bowel.

Having some of the symptoms on this list does not mean that you definitely have bowel cancer.

Other conditions can also cause the same symptoms, including irritable bowel syndrome (IBS), diverticulitis (inflammation of pouches in the bowel), inflammatory bowel disease, haemorrhoids, or an anal fissure (cracks in the skin lining the anus).

Talk to your doctor if you have any of these symptoms, especially if they are ongoing, get worse, or if there is any bleeding.

Bowel cancer risk factors

The causes of bowel cancer are not known. Regular screening is important because bowel cancer can develop without noticeable symptoms.

Anything that can increase your risk of cancer is called a risk factor. For bowel cancer, these include: older age – bowel cancer is more common in people over 50, but the number of younger people being diagnosed is increasing

• polyps – most polyps can become bowel cancer; having a large number of polyps in the bowel is a strong risk factor
• dietary factors – a diet that is low in fibre, fruit, vegetables and wholegrains, and high in red and processed meats such as salami, ham and bacon
• smoking – increases your risk of bowel cancer and bowel polyps
• drinking alcohol – the less alcohol you drink, the lower your risk.
• body weight – being above a healthy weight
• physical inactivity – not moving your body enough. Be active on most days and minimise long periods of sitting
• strong family history – a small number of bowel cancers and types of polyps run in families
• other bowel diseases – inflammatory bowel diseases, such as Crohn’s disease or ulcerative colitis, significantly increase risk, particularly if you have had the disease for more than 10 years (IBS does not increase your risk)
• other cancers – people who have had bowel cancer are more likely to develop a second bowel cancer; some people who have had ovarian cancer or cancer of the uterus, or who have had radiation treatment to the abdomen/pelvis, may also have an increased risk of bowel cancer
• type 2 diabetes – this may increase your risk of bowel cancer
• rare genetic disorders – some bowel cancers are linked to an inherited gene or condition (e.g. cystic fibrosis).If you are worried about your risk of bowel cancer, speak to your GP (doctor).

Bowel cancer in families

The risk of developing bowel cancer may be higher if one or more of your close family members (such as a parent, brother or sister) has had bowel cancer. The risk is higher if they were diagnosed before the age of 50, or if two or more close relatives have had bowel cancer. A family history of some other cancers, such as cancer of the uterus (endometrial cancer), may also increase the risk.

Some people have an inherited faulty gene that increases their risk of developing bowel cancer. These faulty genes cause a small number (about 5–6%) of bowel cancers. There are two main genetic conditions that occur in some families:

• Familial adenomatous polyposis (FAP) – This condition causes hundreds of polyps to form in the bowel. If these polyps are not removed, they may become cancerous.
• Lynch syndrome – This syndrome causes a fault in the gene that helps the cell’s DNA repair itself. People with Lynch syndrome have an increased risk of developing bowel cancer, cancer of the uterus, and other cancers such as kidney, bladder and ovarian.

If you are worried about your family history, talk to your doctor about having regular check-ups or ask for a referral to a family cancer clinic.

Types of bowel cancer

Most bowel cancers are adenocarcinomas. This means they start in the tissue lining the bowel. Rarely, other less common types of cancer can also affect the bowel. These include:

• squamous cell cancers
• neuroendocrine tumours (NETs)
• small bowel cancer
• gastrointestinal stromal tumours
• lymphomas.

Diagnosis of bowel cancer

Several tests can be used to diagnose bowel cancer including:

• Physical and rectal examination
• Blood tests – including a carcinoembryonic antigen (CEA) test and immunochemical faecal occult blood test (iFOBT)
• Colonoscopy polypectomy and biopsy
• PET-CT scan
• CT scan
• MRI scan
• Genomic testing – may be used to look for gene changes (mutations) and other features in the cancer cells that may cause them to multiply and grow. Results can help decide which treatments may or may not work for you
• CT colonography
• Flexible sigmoidoscopy.

Waiting for test results

Test results may take a few days to come back. It is natural to feel anxious waiting to get your results. It can help to talk to a close friend or relative about how you’re feeling. You can also contact Cancer Council on 13 11 20 and speak with a cancer nurse.

Bowel cancer stages

Knowing if and how far the cancer has spread is called ‘staging’ the disease. Staging helps your doctor work out the best treatment for you.

In Australia, the staging system for bowel cancer is the TNM system, which stands for tumour-node-metastasis, which gives numbers to:

• how deep the tumour has gone into the bowel (T1 - 4)
• whether or not lymph nodes are affected (N1 - 2)
• whether the cancer has spread or metastasised outside the bowel (M0 - M1)

The Australian Clinico-Pathological Staging (ACPS) system may also be used in some hospitals.

Based on the TNM numbers, the doctor then works out the cancer’s overall stage:

• stage 1: tumour is found only in the inner layers of the bowel wall
• stage 2: tumour has spread deeper into the layers of the bowel wall
• stage 3: tumour is in any layer of the bowel wall and has spread into nearby lymph nodes
• stage 4: tumour has spread beyond the bowel to other parts of the body, such as the liver or lungs, or to distant lymph nodes.

Around half of all bowel cancers in Australia are diagnosed at stage 1 or 2.

Ask your doctor to explain the stage of your cancer in a way you can understand. This will help you to choose the best treatment for your situation.

Treatment for bowel cancer

Your health care team will recommend treatment based on:

• what will give you the best outcome
• where the cancer is in the bowel
• whether and how the cancer has spread
• your general health
• your preferences.

Surgery

Surgery is the main treatment for bowel cancer. The aim of surgery is to remove as much of the cancer as possible and nearby lymph nodes.

Surgery may be performed as keyhole or open surgery.

The most common type of surgery is a colectomy (removal of part of the colon). Lymph nodes near the cancer are also removed. The surgeon cuts the bowel on either side of the cancer (with a small border of healthy tissue called the margin) and then joins the two ends of the bowel back together. This join is called an anastomosis.

Having a stoma

Sometimes one end of the bowel is brought through an opening made in your abdomen and stitched to the skin. Called a stoma, it allows waste (faeces, stools or poo) to leave the body and be collected in a bag. There are two main types of stoma (colostomy and ileostomy).

The stoma is usually temporary, and the operation is reversed later. In some cases, the stoma is permanent. Improved surgical techniques mean fewer people need a permanent stoma.

Before your surgery, you will be given a lot of education and support about having a stoma.

Chemotherapy and radiotherapy

Chemotherapy or radiotherapy (also known as radiation therapy) may be used in addition to surgery.

Radiation therapy is often used before surgery and may be used with chemotherapy to reduce the size and number of cancer cells.

Radiation therapy may be recommended for rectal cancer but is rarely used to treat colon cancer. It may be given on its own or with chemotherapy (chemoradiation), which makes cancer cells more sensitive to radiation.

You may have radiation therapy before surgery to shrink the tumour, making it easier to be removed and reducing the risk of the cancer coming back. Occasionally, if the cancer is more advanced, radiation therapy may be used after surgery to destroy any remaining cancer cells.

If the cancer has spread outside the bowel to lymph nodes or to other organs, chemotherapy may be recommended:

• Before surgery – to shrink the tumour and make it easier to remove.
• After surgery – to kill any remaining cancer cells and reduce the chance of the cancer coming back.
• On its own – if the cancer has spread to other organs.

Your doctor will discuss your treatment in detail with you.

Drug therapies

Advanced bowel cancer is commonly treated with drugs that reach cancer cells throughout the body. This is called systemic treatment, and includes chemotherapy, immunotherapy and targeted therapy.

Targeted therapy is a type of drug treatment that attacks specific features of cancer cells to stop the cancer growing and spreading. Monoclonal antibodies are the main type of targeted therapy drug used in Australia for advanced bowel cancer.

Immunotherapy uses the body’s own system to fight cancer. Checkpoint inhibitors are the main type of immunotherapy drug used for the small number of advanced bowel cancers that have a fault in the mismatch repair (MMR) gene.

Radiation therapy

Radiation therapy can be used as a palliative treatment for both advanced colon and advanced rectal cancer. It can be used to control the growth of the tumour and relieve symptoms such as bleeding. If the cancer has spread to the bone or formed a mass in the pelvis, radiation therapy can reduce pain.

If the tumour has spread to the liver, you may be offered a specialised type of radiation therapy. Options may include selective internal radiation therapy (SIRT, also called radioembolisation) or stereotactic body radiation therapy (SBRT).

Thermal ablation

If the cancer has spread to only a small number of places in a single area, such as the liver or lungs, your doctor may recommend thermal ablation. This may use heat to destroy the tumour.

The heat may come from radio waves (radio frequency ablation) or microwaves (microwave ablation). It is best performed in a specialised centre. Cryoablation is a similar process that may sometimes be offered, and uses cold or freezing instead of heat.

Side effects of bowel cancer treatment

All treatments have side effects. These will vary depending on the type of treatment you are having. Many side effects are temporary, but some may be permanent. Your doctor will explain all the possible side effects before your treatment begins.

Radiation therapy to the pelvis and rectum can affect your sexual function and ability to have children (fertility). It is important to discuss your options with your doctors before you start treatment.

Some side effects can be upsetting and difficult, but there is help if you need it. Call Cancer Council 13 11 20 or contact cancer support to speak with a caring cancer nurse for support.

Living with a stoma

Most people find it takes time to come to terms with having a stoma. It is a big change in your life.

People often worry about how they will care for their stoma. A stomal nurse will explain how to care for your stoma and tell you about support services.

Sexuality and bowel cancer

Having bowel cancer and treatment can change the way you feel about yourself, other people, relationships and sex. These changes can be very upsetting and hard to talk about. Doctors and nurses are very understanding and can give you support. You can ask for a referral to a counsellor or therapist who specialises in body image, sex and relationships.

Living with advanced cancer

Advanced cancer usually means cancer that is unlikely to be cured. Some people can live for many months or years with advanced cancer. During this time palliative care services can help.

Most people continue to have treatment for advanced cancer as part of palliative care, as it helps manage the cancer and improve their day-to-day lives.

Many people think that palliative care is for people who are dying but palliative care is for any stage of advanced cancer. There are doctors, nurses and other people who specialise in palliative care.

Treatment for advanced bowel cancer may include chemotherapy, radiation therapy, surgery or another type of treatment. It can help in these ways:

• slow down how fast the cancer is growing
• shrink the cancer
• help you to live more comfortably by managing symptoms, like pain.

Treatment depends on:

• where the cancer started
• how far it has spread
• your general health
• your preferences and what you want to do.

Ask your doctor about treatment and palliative care services that may help you.

Caring for someone with bowel cancer

Caring for someone with cancer can be a difficult and emotional time. If you are caring for someone with bowel cancer, these organisations can help:

• Cancer Council Victoria 13 11 20
• Carer Gateway 1800 422 737
• Carers Australia 1800 242 636

Reducing your risk of bowel cancer

For people aged 45 to 74 and at average risk of bowel cancer, having regular screening for bowel cancer is the most effective way to reduce your risk of bowel cancer.

You can also help to reduce your risk of bowel cancer by:

• eating a healthy diet with plenty of fresh vegetables and fruit
• limiting your consumption of red meat and processed meats
• maintaining a healthy body weight
• daily physical activity
• quitting smoking
• reducing your alcohol intake.

Following this advice doesn’t mean that you will never get bowel cancer, but it can reduce your risk and has other health benefits too.

Screening for bowel cancer

Screening is the process of looking for cancer, or abnormalities that could lead to cancer, in people who do not have any symptoms. It is particularly important for bowel cancer, which often has no symptoms in its early stages.

The National Bowel Cancer Screening Program (NBCSP) sends free at-home bowel cancer screening test to all eligible Australians aged 50 to 74, every 2 years. People ages 45 to 49 can request their first kit at the National Cancer Screening Register website or call 1800 627 701. All eligible people aged 45 to 74 can also ask their doctor about getting a free test kit.

A test kit can also be purchased from some pharmacies.

The screening test used is called the faecal occult blood test (iFOBT). This involves taking tiny samples from two separate bowel motions (poo) using a test kit. The samples are then posted to a laboratory for testing.

If blood is detected, the doctor is likely to refer you for a colonoscopy. Most positive tests are not the result of cancer. However, if cancer is detected early, there is a higher chance of it being treated successfully.

You can access more information about bowel cancer screening from the national Department of Health and the Indigenous Bowel Screen websites.

Where to get help

• Your GP (doctor)
• Your cancer specialist (oncologist)
• Your treatment team
• Cancer Council Victoria Tel. 13 11 20 (to speak to someone in a language other than English call 13 14 50 and ask to speak to Cancer Council)
• Cancer Council Victoria, My Cancer Guide - Find support services that are right for you.