Colon cancer, also known as colorectal cancer, starts from small benign growths or polyps that form in the lining of the colon. While larger polyps can potentially cause symptoms like blood or mucus in the stool, often, these growths do not display any symptoms at all. Screening for colon cancer allows for the detection of asymptomatic polyps that have the potential to become malignant. Your specialist doctor will remove them by performing a simple removal during the endoscopy.
Screening tests provide a great opportunity to prevent colon cancer, as well as to detect it at an early stage when treatment is most effective. There are various screening options available today. Amongst the various options, a colonoscopy provides the highest accuracy, providing both diagnosis of colorectal cancer and prevention of cancer by removal of polyps.
If you have a family history of colon cancer or polyps, especially among first-degree relatives, you are at a higher risk of getting it as well. Inherited genetic disorders such as familial adenomatous polyposis (FAP) and hereditary non-polyposis colon cancer (HNPCC) puts one at a higher risk of getting colorectal cancer.
If you have been experiencing long-term (chronic) inflammatory bowel disease (Ulcerative colitis or Crohn’s disease affecting the colorectum), you are also at increased risk of developing colorectal cancer.
Individuals aged 50 and above who have an increased risk of colorectal cancer are recommended to go for regular screening, to prevent and detect cancer early.
Dr. Sim Hsien Lin’s main sub-specialty is in colorectal surgery. In addition, her sub interests include laparoscopic colorectal surgery, transanal endoscopic microsurgery, management of piles, inflammatory bowel diseases, complex anal fistulas as well as diagnostic and therapeutic endoscopic procedures.
Dr. Sim Hsien Lin is a specialist colorectal surgeon in Singapore with over 10 years of experience in colorectal surgery. Her sub interests include laparoscopic colorectal surgery, transanal endoscopic microsurgery (TEMS), surgical management of piles, inflammatory bowel diseases and complex anal fistulas.
FIT or iFOBT is a preliminary test that uses antibodies to detect small amounts of blood (usually invisible to the naked eye) in your stool. For this testing method, you collect a sample of your stool, using a simple test kit obtained from your doctor and send it back to them. This test should be done every year, especially if you are over 50 years old.
gFOBT uses the chemical guaiac to look for hidden blood in your stool which may be caused by colon cancer. The test is taken at home using a special kit available from your specialist doctor. This test should be repeated every year.
This test combines the FIT with the test that searches for abnormal DNA changes in cells that can be triggered by colorectal polyps or cancer. This test is done using a special take-home kit which is then sent to the laboratory. This test should be performed every 1-3 years. However, this is not widely available in Singapore.
DCBE involves pouring a barium solution in the colon through the back passage, entirely covering the inside of the bowel. This provides an outline of the colon on the x-ray images, highlighting any abnormal areas. A DCBE is done every 5 years.
Sigmoidoscopy is a minimally invasive examination of the large intestine from the rectum through left-sided colon. The test allows your rectum and left-sided colon to be screened for any abnormal growths. It is performed using a sigmoidoscope – a thin, flexible tube with a lens and a tool for removing tissue for biopsy. With this screening method, your specialist doctor will not be able to examine the proximal part of the colon. A flexible sigmoidoscopy should be done every 5 years.
Computed tomography (CT) colonography, also known as virtual colonoscopy, is a non-invasive procedure that utilises x-ray equipment to produce a set of pictures of the colon from various angles. These pictures are then displayed on a monitor screen for the radiologist to analyse. A CT colonography should be repeated every 5 years. This examination requires some form of bowel preparation and small lesions may not be picked up.
This screening method involves using a tiny flexible tube with a lens and a small camera on the end that is carefully inserted through your back passage advancing into the colon to check the entire area. For individuals with an average risk of colon cancer, undergoing a colonoscopy once every 10 years is sufficient.
Colonoscopy screening is the most comprehensive and accurate method of detecting and preventing colon cancer available today.
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A successful colonoscopy first requires your bowels to be clear of solid waste. You will need to take laxatives to stimulate bowel movement and ensure a clean colon. If your colon is not completely empty, remaining stool debris may make it difficult to detect problems present in your bowels.
Depending on each individual case, Dr. Sim and her clinical team will walk you through a thorough plan for your bowel prep.
A colonoscopy typically takes 20-30 minutes.
If necessary, you may choose to take a sedative to ensure you are relaxed and comfortable during the whole process. A colonoscope with a built-in camera on the end will be carefully inserted through your back passage until it reaches the end of your colon. To ensure a clear view, air will be pumped in through the tube into your bowel which may be associated with slight discomfort.
Your specialist doctor may ask you to change your position during colonoscopy. This is normal and it helps them to investigate different parts of your colon more thoroughly.
Any polyps found during the procedure will be painlessly removed and biopsies will be taken for further tests, if necessary.
A colonoscopy is usually done on an outpatient basis, meaning you will not have to stay in a hospital overnight.
If you have received a sedative, you will need to wait until the sedative effects wear off which takes about a few hours. When you are ready, your specialist doctor will discuss the results of your colonoscopy with you. Ideally, someone should accompany you on your way home. Since sedatives affect coordination and judgement, you should avoid drinking alcohol, driving for 24 hours and operating machinery.
You may experience some wind and mild stomach cramps along with bloatedness for a few hours after the procedure. This is due to the air blown into your colon for visualisation. You should be able to get back to your daily activities the next day.
We recommend that all individuals aged 50 years and above, regardless of gender and ethnicity undergo a colonoscopy.
A colonoscopy is strongly advised if you experience symptoms of colon cancer, such as rectal bleeding, a change in bowel habits or blood in your stools. You should also get a colonoscopy if your immediate family member was diagnosed with colon cancer since that puts you at an increased risk.
If you are at average risk for colon cancer, you should start undergoing colonoscopy screening at the age of 50. If the first testing is negative, you can get tested once every 10 years. However, you should discuss the suitable frequency of your colonoscopy tests with your specialist doctor.
People are considered to be at average risk for colon cancer if they do NOT have:
If you have any of the above conditions, you are considered to be at increased or high risk of getting colon cancer. In this case, you should start colonoscopy screening before the age of 50. There are no universal guidelines since they vary depending on your particular situation. You should consult your specialist doctor to define an optimal schedule.
Colonoscopy involves a slight discomfort from time to time during the procedure but we aim to make it minimal. You can choose to receive sedation to ensure you are relaxed and comfortable during your colonoscopy.
Yes, you can choose to perform a colonoscopy without sedation. In this case, you will be able to watch the procedure on the screen and drive yourself back home once it is complete. Undergoing a colonoscopy without sedation is safe but do expect some discomfort.
If you were given a sedative, you may feel drowsy after the procedure.
You may also feel bloated and have stomach cramps because of the air pumped into your colon during the examination. This is normal and settles within a few hours after your colonoscopy.
A colonoscopy is a safe procedure with a very low risk of complications occurring less than once in every 1000 procedures. Possible complications include perforation (tear) in the wall of the bowel and severe bleeding at the site of biopsy.