About Bowel Cancer

What is Bowel Cancer?

Bowel cancer, also known as colorectal cancer or colon cancer, is a type of cancer that affects the colon (large intestine) and rectum. The colon and rectum are part of the digestive system and are responsible for absorbing water and nutrients from food and eliminating waste from the body.

Bowel cancers start in the lining or the innermost tissue layer of the bowel walls. It usually begins as a small growth or polyp, which can develop into cancer over time. Research suggests that most bowel cancers can take 5 to 10 years or more to develop. If left untreated, it can also spread to other body parts, such as the liver and lungs.

Types of Bowel Cancer

• Adenocarcinoma: The most common type of bowel cancer, accounting for more than 90% of cases. It develops from cells in the lining of the colon or rectum.
• Carcinoid tumours: These are rare types of bowel cancer that develop from cells in the lining of the gut. They are usually slow-growing and may not cause symptoms for many years.
• Gastrointestinal stromal tumours (GISTs): These are rare types of bowel cancer that develop in the muscle or connective tissue of the gut. They may only cause symptoms once they grow very large.
• Lymphoma: This is a rare type of bowel cancer that develops in the lymphatic system, which helps to fight infection. It can occur anywhere in the bowel.

Who is Most at Risk for Bowel Cancer?

Bowel Cancer is more common in developed countries. It affects over 4% of Australians, with over 15,000 sufferers annually and about 5,000 deaths. Known factors that will increase your risk are:

• Age: Most cases occur in people over 50, although there is an increasing incidence of younger patients with bowel cancer
• Family history: If you have a close relative (parent, sibling, or child) who has had bowel cancer.
• Personal history: If you have had bowel cancer before, you are at increased risk of developing it again, or if you have ongoing inflammatory bowel diseases such as ulcerative colitis or Crohn’s Disease.
• Inherited conditions: Genetic conditions, such as Lynch syndrome/Hereditary Non-Polyposis Colorectal Cancer (HNPCC), familial adenomatous polyposis (FAP), MYH-associated polyposis (MAP), and the hamartomatous polyposis syndromes (Peutz–Jeghers, juvenile polyposis, and Cowden disease). 
• Lifestyle factors: A diet high in processed meats and low in fibre, smoking, heavy alcohol use, obesity and lack of exercise

Causes of Bowel Cancer

The exact cause of bowel cancer is not known, but several factors are thought to contribute to its development. These include:

• Genetic mutations: Changes in certain genes can increase the risk of bowel cancer. These changes may be inherited or acquired over time.
• Polyps: Bowel cancer often develops from polyps, which are small growths on the lining of the colon or rectum.
• Inflammation: Long-term inflammation of the colon or rectum, such as in inflammatory bowel disease (IBD), can increase the risk of bowel cancer.
• Lifestyle factors: Certain lifestyle factors can increase the risk of bowel cancer.

Preventing Bowel Cancer

While some risk factors for bowel cancer, such as age and family history, cannot be controlled, there are several steps you can take to reduce your risk of developing this disease. These include:

• Regular screenings: Screening tests can detect bowel cancer early when it is easier to treat. If you are over 50 or have a family history of bowel cancer, speak to your doctor about screening options. There is some evidence that screening should commence at the age of 45. 
• Eating a healthy diet: A diet rich in fruits, vegetables, and whole grains and low in processed meats and alcohol can help to reduce your risk of bowel cancer.
• Maintaining a healthy weight: Being overweight or obese can increase your risk of bowel cancer, so it is important to maintain a healthy weight through regular exercise and a balanced diet.
• Quitting smoking: Smoking is a major risk factor for many types of cancer, including bowel cancer, so quitting smoking can help to reduce your risk.
• Reducing alcohol consumption: Heavy alcohol use can increase your risk of bowel cancer, so it is important to drink alcohol in moderation.

Symptoms of Bowel Cancer

Common symptoms of bowel cancer include:

• A change in bowel habits, such as constipation or diarrhoea
• Blood in the stool
• Abdominal pain or discomfort
• Bloating or a feeling of fullness
• Unexplained weight loss
• Fatigue or weakness
• Low blood count or anaemia

Colon cancer often does not cause symptoms until late stages, while rectal cancer can result in bleeding, rectal pain, and urgency to defecate (tenesmus). All cancers can cause obstruction, leading to abdominal distention, vomiting and pain.

Stages of Bowel Cancer

Bowel cancer is staged based on the size of the tumour and whether it has spread to other parts of the body. The stages of bowel cancer are:

• Stage 0: The cancer is only in the inner lining of the colon or rectum and has not spread to other tissues.
• Stage I: Cancer has grown into the deeper layers of the colon or rectum but has not spread to the lymph nodes or other body parts.
• Stage II: Cancer has grown into or through the wall of the colon or rectum but has not spread to the lymph nodes or other parts of the body.
• Stage III: Cancer has spread to nearby lymph nodes but not to other parts of the body.
• Stage IV: Cancer has spread to other body parts, such as the liver or lungs.

Significant improvements have been made in treating bowel cancer over the past decade, and modern combination treatments can achieve excellent results. Despite a poor prognosis with late-stage III cancer, where metastasis has spread to other organs, there could still be a role for surgery or combination treatments. It is recommended that you discuss options with your doctor.

How is Bowel Cancer Diagnosed?

Screening for Bowel Cancer

The incidence of bowel cancer remains high, but the overall mortality rate has decreased due to screening, early intervention, and improved treatments. Australians over 50 are recommended to undergo bowel cancer screening.

• Faecal occult blood test (FOBT): The FOB test is performed on stool samples collected by the patient, detecting small amounts of blood, which can be a sign of bowel cancer. Screening programs using FOB are being developed in Australia, and studies have shown that populations screened with FOB have a lower risk of dying from bowel cancer.
• Colonoscopy: A doctor uses a thin, flexible tube with a camera on the end to look inside the colon and rectum. Polyps found can be removed before they turn into cancer.
• Biopsy: During a colonoscopy, your doctor may take a small sample of tissue (biopsy) from any suspicious areas for testing.
• CT scan: This type of X-ray can create detailed images of the inside of your body, including your colon and rectum. CT scans are not accurate at diagnosing polyps or early stages of cancer.

Tests for Bowel Cancer

If your doctor suspects you may have bowel cancer, internal examinations of the back passage and special tests will be organised. Immediate examinations can include:

• digital rectal examination
• endoscopic examination using colonoscopy (all of the large bowel)
• CT colonography that outlines the colon
• (Internal) endorectal ultrasound examination
• MRI scan of the pelvis and rectum
• Occasionally, a PET CT is also required to rule out distant spread (metastases).

How can Bowel Cancer be Treated?

Bowel cancer treatment depends on the cancer stage and other factors, such as age and overall health. The main treatment options include:

• Endoscopy: Endoscopic resection may be possible for very early stages of bowel cancer.
• Surgery: This is the most common treatment for bowel cancer. Surgery aims to remove the cancerous tumour and any nearby lymph nodes.
• Chemotherapy: This is a type of medication that can kill cancer cells or stop them from growing. It is often used after surgery to kill any remaining cancer cells.
• Radiation therapy involves using high-energy X-rays or other types of radiation to kill cancer cells. It is sometimes used in combination with chemotherapy.

Combination Treatments

Bowel Cancer can be cured with a combination of surgery, chemotherapy, and/or radiotherapy. Patients with localised bowel tumours that have spread to the lymph glands may receive chemotherapy or radiotherapy before or after surgery to reduce the size of the cancer, the chance of spread, and the chance of recurrence. Patients with liver metastases may receive chemotherapy after bowel surgery or liver tumour removal. 

Adjuvant treatment is used to prevent cancer spread. In some cases, chemotherapy is used alone in a palliative setting to relieve symptoms when cancer has spread and cannot be completely removed.

Bowel Cancer Surgery

Preparing for Bowel Cancer Surgery

Before any procedure, your doctor or a staff member will advise you of the details, but in general, you will need to

• Only consume clear liquids the day before your surgery. 
• Take a bowel prep, an oral laxative, to clean out your colon.
• You need to fast (from midnight before your morning surgery or 6 am if you have afternoon surgery.

During Bowel Surgery

When bowel cancer has been diagnosed, the affected parts of the colon and rectal should be removed quickly. If treated aggressively with surgery, colorectal cancers frequently do better than other cancers. The procedures are called:

• Colectomy: removal of a portion of colon or bowel resection
• Procto-colectomy: removal of the rectum and a part of the colon

Postoperative Care Plan

Your care plan may involve the following:

• regular appointments every 1-3 years
• blood tests to test for cancer recurrence
• a colonoscopy one year after your operation
• a CT scan of the abdomen & pelvis every 1-2 years (initially) 

Bowel Cancer Survival

The outcome (prognosis) for Bowel Cancer will depend on several factors, including:

• The growth pattern of primary bowel cancer
• The depth cancer has spread through the bowel wall
• The presence of cancer cells in lymph glands and other organs 
• A patient's general health and well-being

In patients with bowel cancer confined to the bowel and who undergo surgery, the chance of cure is around 55%. About 20% of patients present with liver metastases; another 20% will develop them later. Many patients are suitable for surgery to remove liver tumours, and approximately 50% of those with isolated liver metastases who undergo complete resection will be cured. Survival outcomes have improved dramatically over the past 20 years. Bowel cancer has a good prognosis if detected early.

What if Bowel Cancer is Untreated?

If left untreated, bowel cancer can spread to other body parts, such as the liver, lungs, or brain. This can cause a range of complications, including:

• Intestinal blockage: Cancer can grow large enough to block the intestine, which can cause abdominal pain, constipation, and vomiting.
• Malnutrition: Bowel cancer can affect your ability to absorb nutrients from food, which can cause malnutrition and weight loss.
• Bowel perforation: Cancer growing through the colon or rectum's wall can cause a hole (perforation) in the bowel, leading to infection and other complications.
• Metastasis: If cancer spreads to other body parts, it can be much harder to treat and may become life-threatening.