Colorectal cancer is one of the most common cancers and causes of cancer death. Fortunately, there are screening tests that can be done to detect colorectal cancer early.

Do take note that screening test are recommended for those who do not have any symptoms:

• Blood in stools
• Change in bowel habits (e.g. chronic constipation, chronic diarrhoea or alternating constipation and diarrhoea)
• Abnormal stools (change in stool size/consistency)
• Chronic abdominal pain
• Rectal or abdominal mass

If you have any of the above symptoms, please see a doctor for further evaluation.

Types of Screening Test:

In general, there are 2 types of screening test that are recommended, as detailed in the table below.

	Colonoscopy	Stool Test
What is it?	Allows the doctor to see directly inside the entire colon by inserting a thin tube with a camera attached into the anus and advancing it into the colon. Before you have a colonoscopy, you must clean out your colon by drinking a special liquid that causes watery diarrhea for several hours. On the day of the test, you get medicine to help you relax, if you want.	Most commonly check for blood in samples of stool. Cancers and abnormal growths in the colon can bleed, and if they bleed around the time that you do the stool test, blood will show up on the test. Can find even small amounts of blood that you cannot see in your stool.
Advantages	Most accurate test to directly look for abnormalities in the colon. Any abnormal growth (polyps) that is small can be directly removed during the scope to send for testing.	Does not involve cleaning out the colon or having any procedures.
Disadvantages	Colonoscopy has some risks. It can cause bleeding or tear the inside of the colon, but this only happens in 1 out of 1000 people. Cleaning out the bowel beforehand can be unpleasant. Will likely not be able to work or drive for the rest of the day after the test, because of the relaxation medicine taken during the test.	Less likely to find abnormal growths (polyps) in the colon than a colonoscopy. May turn out abnormal even in people who do not have cancer. If a stool test shows something abnormal, a follow up with a colonoscopy will be necessary.
Recommended age*	50-75 years old**	50-75 years old**
Recommended frequency of test*(assuming previous test is normal)	Every 10 years	Every year

Frequency of Test & When To Start Screening For Higher-Risk Individuals:

A colonoscopy rather than a stool test will be recommended for higher-risk individuals as detailed below.

Risk Group	Age To Start Screening	Frequency
Colorectal cancer or documented advanced polyp in the first degree relative* age 60 years or younger or two or more first-degree relatives	10 years prior to the youngest case in the family or 40 years old, whichever is earlier	Every 5 Years
Colorectal cancer or or documented advanced polyp in the first degree relative over the age of 60 years	50 years old	Every 10 Years
A family history of familial adenomatous polyposis	10 to 12 years old	Annually
A family history of hereditary non-polyposis colorectal cancer	20 to 25 years old	Every 1 to 2 years

It is therefore very important to check with your family for any history of the above as you may require a colonoscopy earlier.

Note: If you have other conditions such as previous polyps found on colonoscopy, inflammatory bowel disease or other cancers, please check with your specialist about the specific colorectal cancer screening recommendations.

Colorectal Cancer Marker Usefulness:

Some health screening packages contain this cancer marker called carcinoembryonic antigen (CEA). Neither CEA nor other cancer markers have been shown to be a good screening test for colorectal cancer.

A negative CEA does not necessarily mean there is no colorectal cancer, whereas a positive CEA does not necessarily mean there is colorectal cancer. Moreover, many other factors not related to colorectal cancer can cause CEA to be raised, such as smoking, diabetes and gastritis.

CEA is only used for patients that are already diagnosed with colorectal cancer to provide information on prognosis as well as for follow-up on the cancer treatment.

Hence, it is not recommended to use CEA for colorectal cancer screening as it may incur unnecessary costs as well as worry.

Take Home Points:

• Find out from your family if there is any family history of colorectal cancer or colorectal conditions.
• Go for colorectal cancer screening at the recommended age and intervals as detailed above.
• Do not use rely on CEA for colorectal cancer screening.

Useful Material: Singapore Cancer Society Stool Test User Guide

Related Health Screening Articles:

• Tips For Health Screening
• High Blood Pressure Screening
• ABPI Made Easy: A Simple Guide to Assessing Ankle-Brachial Pressure Index
• Are You At Risk for Obstructive Sleep Apnea (OSA)?
• Preventing the Plunge: Essential Screening for Fall Risk
• Are Your Bones Strong? The Essential Guide to Osteoporosis Screening & Prevention
• Colorectal Cancer Screening
• Cervical Cancer Screening

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