Bowel cancer screening

http://www.umediagnostics.com/health-screening/bowel-cancer-screening/

Colon cancer is one of the most common cancers in the western world. Most colon cancers start as small growths called polyps. The aim of screening the colon is to detect these polyps.

Colon scan or Virtual colonoscopy is a minimally invasive alternative to conventional colonoscopy (endoscopy) that screens the colon and rectum for polyps and early cancer before symptoms occur. Polyps are small masses of cells that grow out of the lining of the colon and rectum and can become cancerous over time. Detecting clinically significant polyps and cancer early with virtual colonoscopy allows for treatment at a stage when disease can be prevented or cured, before it spreads to other parts of the body.

Virtual colonoscopy involves no scopes, sedation or recovery time.  It is performed on a Computed Tomography (CT) scanner which takes two-dimensional (2D) and three-dimensional (3D) images of the colon in just 5 minutes. The combination of 2D and 3D images increases the radiologist’s ability to detect and analyse areas of concern. The 3D images allow the radiologist to reconstruct the colon and do a ‘fly-through’ of its entire length, simulating the views of conventional colonoscopy.

What is the difference between conventional colonoscopy and virtual colonoscopy?

Conventional Colonoscopy	Virtual Colonoscopy
Takes 30 minutes.	Takes 5 minutes.
Preparation includes oral laxative and clear diet 24 hours before procedure.	Preparation includes oral laxative and clear diet 48 hours before procedure.
Sedation delivered intravenously with a needle.	No sedation.
Insertion of a long, flexible scope into the rectum that is guided up the length of the colon.	Minimally invasive insertion of a small, disposable tube two inches inside the rectum to fill the bowel with CO2.
Scope can only view the inner surface of the colon directly ahead and cannot examine narrow areas or both sides of folds in the bowel. Cannot determine exact location of a polyp.	The 3D fly-through allows the radiologist to turn, zoom, and rotate the view in forward and reverse motion, which helps visualize complex folds or narrow areas of the colon. Polyps can be located exactly, marked, and measured electronically. Both the inner and outer surface of the colon plus the surrounding organs can be seen.
Polyps can be removed immediately.	Clinically significant polyps must be removed through conventional colonoscopy.
10% of patients have a failed colonoscopy.	Used with patients who have had a failed colonoscopy.
Risk of perforation (1 in 500-1000).	Minimal risk of perforation (1 in 3000).
Long recovery from sedation with a missed day of work.	No recovery period and no missed day of work.

Why is screening for colorectal cancer important?

In its early stages, colorectal cancer causes no symptoms in the patient. Most colorectal cancers begin as small precancerous (adenomatous) polyps that can take 3 to 10 years to progress to cancer. Approximately 8% to 12% of untreated polyps become cancerous tumours. The risk of a polyp becoming cancerous is related to its size. A polyp smaller than 5 mm has essentially no risk of becoming cancerous, whereas a 10 mm to 20 mm polyp has a 10% risk, and those larger than 20 mm have a 30% or greater risk.

When screening is performed regularly, polyps can be identified so they can be removed before they have the chance to become cancerous. Removal of precancerous polyps is essential and has the potential to reduce the incidence (new cases) of colorectal cancer by 40%. The 5-year survival rate for patients with tumours localised to the bowel is 90%. For tumours that spread to parts of the body outside the colon, the five-year survival rate is 8%.

Who should have a colon scan?

Men and women over 50 years of age should have a colon scan if they have one or more of the following risk factors or symptoms:

• Family history of bowel disease.
• Familial adenomatous polyposis.
• Blood in the stools.
• Constipation.
• Tiredness.
• Abdominal discomfort.
• Previously diagnosed with colonic polyps or cancer and would prefer a less invasive alternative.
• Persistent change in bowel habit.

Can colorectal cancer be prevented?

Screening for colorectal cancer is important because there is no way to completely prevent the disease. According to the American Cancer Society, regular screening and certain lifestyle choices (eg, nutrition, physical activity) can greatly reduce the risk of developing colorectal cancer. Regular screening has been shown to reduce risk by at least 33%. Lifestyle choices thought to decrease the risk of colorectal cancer include:

• Maintaining an ideal body weight.
• Eating a healthy diet that includes:
  • 5 or more servings of vegetables and fruit a day;
  • whole grains;
  • foods high in calcium;
  • a limited consumption of high-fat dairy products, fried food, and red meat.
• Refraining from smoking or excessive alcohol intake (more than 1 drink per day).
• Regular exercise (30 minutes or more of moderate exercise per day, or 1 hour of brisk walking per day).

For information on how to book an appointment please see the booking and payment page, or contact your nearest centre.