Q:

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Colorectal cancer runs in my family. What tests should I take to detect it early?

Colorectal cancer is the second most common cause of cancer in Singapore (after breast cancer in women and after lung cancer in males). There are four recommended screening tests to choose from, each with different degrees of accuracy, frequency of examination, cost, risk and degree of invasiveness:

1. The cheapest and easiest to perform, but least accurate is the annual faecal occult blood test (FOBT). FOBT can be performed on faecal samples by most primary healthcare providers. It detects tiny or hidden traces of blood in your stool, which may indicate the presence of disease (bleeding from a colon or rectal polyp or tumour). If your test result is positive, your doctor will refer you for a further examination (e.g. a colonoscopy) to determine the cause of the bleeding.

2. A barium enema is an x-ray procedure performed by a radiologist (x-ray specialist) after air and a liquid x-ray contrast is introduced via the anus to the whole colon. The recommended frequency for barium enema for an average risk individual is every five to 10 years.

3. A flexible sigmoidoscopy (FS) allows the direct examination of the inside lining of your rectum and only the left side of the colon. It usually takes five to 10 minutes and is sometimes done under sedation. This test is recommended once every five years for average risk individuals.

4. A colonscopy is like a FS except the whole colon (both right and left colon) is examined. It usually takes 10 to 30 minutes and is commonly done under sedation.

The colonoscopy is by far the most accurate method for colon cancer screening. For the ‘average risk’ individuals, this test is recommended once every 10 years. For ‘high risk’ individuals with a personal or family history of colon polyps or cancer, like yourself, I’d recommend a colonoscopy, starting 10 years prior to the youngest affected family member or when you reach 50 years old, whichever is earlier.