Medically Reviewed by Dr. Nigel
For many of us, a cancer diagnosis may seem unlikely, but when it comes to colorectal cancer, a sudden cancer diagnosis may be more common than you think.
Colorectal cancer refers to cancer of the large intestine, developing in either the colon or rectum. In Singapore, it is the most common cancer in males and the second most common cancer in females. From 2013 to 2017 alone, there were almost six new cases diagnosed and more than two deaths per day in Singapore, amounting to a total of 10,634 new cases and 4,082 deaths in just four years.
Risk factors for developing colorectal cancer include advanced age, male gender, family history, Chinese race, smoking and obesity.
In its early stages, colorectal cancer is often asymptomatic and may go unnoticed, until the appearance of classic symptoms like persistent bowel discomfort, bloody stools, changes in bowel habits or unexplained weight loss in the later stages. When diagnosed in its later stages, surgery to remove parts or the entirety of the colon becomes the most common choice of treatment.
As with all cancers, colorectal cancer is a serious and difficult medical condition to manage. As caregivers, we must keep a lookout for signs of colorectal cancer in ourselves and our loved ones. We should encourage our family members to go for regular colorectal screening to ensure early detection and treatment.
Why is colorectal cancer screening important?
Colorectal cancer screening is an essential and easy method for us to detect colorectal cancer. By looking for pre-cancer and early cancer in the large intestine, colorectal cancer screening allows for the prevention or early diagnosis and treatment of colorectal cancer.
Colorectal cancer typically develops from benign or non-cancerous growths, called polyps, that grow in the lining of the large intestine. From the moment they develop, it can take up to five to ten years for these non-cancerous growths to turn cancerous.
During this period, the polyps usually do not cause any noticeable symptoms. Without screening, it is thus impossible for the average person to realise that they are at risk of getting colorectal cancer or that they may have early colorectal cancer.
Using various types of tests, colorectal cancer screening detects polyps growing in an individual’s large intestine. They can then be removed through a colonoscopy before they turn cancerous, preventing colorectal cancer.
Even if these polyps have turned cancerous, early detection allows them to be removed before they spread to other parts of the body. Treatment for early colorectal cancer is less complicated and extensive or overly major surgery can still be avoided.
In fact, when found at an early stage, 90% of people continue to survive after five years from their diagnosis.
Who needs colorectal cancer screening?
As a rule of thumb, colorectal cancer screening should begin at the age of 50 for those without any risk factor. It goes without saying, screening should begin earlier for those with risk factors, depending on what risk factors are present.
If you have no symptoms or only have a family history of colorectal cancer outside of your immediate family, you are classified as having an average risk of getting colorectal cancer. It is recommended that you go for colorectal screening starting from age 50. Screening consists of stool testing annually or going for a colonoscopy every 10 years.
The risk factors and recommended screening frequency for increased-risk individuals can be found in the table below:
The risk factors and recommended screening frequency for high-risk individuals can be found in the table below:
What are the different types of screening tests for colorectal cancer?
Faecal Occult Blood Tests (FOBTs)
FOBTs work by detecting haemoglobin, a protein found in blood, in your stools. They are the simplest and cheapest form of colorectal cancer screening tests, only requiring you to provide a stool sample for testing at a laboratory.
Although they do not require any dietary restrictions, FOBTs have low sensitivity with a 50% detection rate for each screening. Positive FOBT results must also be followed by a colonoscopy for confirmation and further investigation.
Colonoscopy is the most accurate and comprehensive colorectal cancer screening test available. It allows for detection and removal of pre-cancerous polyps, thus preventing the progression to cancer. It also allows for biopsy samples to be taken to detect cancerous changes.
A colonoscopy involves the insertion of a long flexible tube into your rectum with a tiny camera attached that allows the doctor to thoroughly inspect your large intestine. The doctor may also pass other instruments and tools through this tube to study and remove any tissue in your large intestine.
Bowel preparation is required prior to the procedure. This involves drinking either high volume (3-4 litres) of polyethene glycol (PEG) or low-volume (90ml) of oral fleet. Patients will be sedated throughout the procedure.
Before a colonoscopy, you should stop taking iron supplements one week before, and pause anti-blood clotting medication like aspirin or warfarin five days before. You should also go on a low fibre diet for three days before and avoid fruits and vegetables including:
- Fresh fruit and vegetable juices
- Vegetable soup
- Red meat
- Milk products
- Cereals and grains e.g. oats, bran, wheat, muesli, barley nuts and beans
You are allowed to continue eating foods including:
- Simple carbohydrates such as white rice, white bread, mee sua, bee hoon, kway teow, potatoes
- Plain coffee, tea, glucose, honey or clear soup.
A colonoscopy typically poses little to no physical risk, but rare complications may include:
- Bad reaction to the anaesthesia used for the procedure
- Internal bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed
- A tear in the colon or rectum wall (perforation)
A barium enema, or a colon x-ray, involves the injection of a liquid containing a metallic substance called barium into your rectum. An x-ray of your colon is then taken to check for abnormalities. Like the colonoscopy, the procedure requires you to completely empty your bowels and observe dietary restrictions beforehand.
During a barium enema exam, the doctor may pump air into your colon. This is to expand your colon and improve the quality of images.
Some risks of a barium enema include:
- tissue swelling around your colon
- blockage in your digestive tract
- tears in your colon wall
- allergic reaction to barium
After the exam, the barium is removed through an enema tube. You may experience white stools for a few days afterwards as your body removes any remaining barium.
This test is not the gold standard or first-line screening option. It should only be used when all else fails.
CT Colonography uses CT scanning to generate images of the colon and rectal wall. You are still required to completely clear your bowels, but there is no need to be sedated for the procedure. If any abnormalities or polyps are discovered in the images, a colonoscopy may be needed. Due to radiation exposure, this screening method is only conducted if colonoscopy fails.
Where can I get screened for colorectal cancer in Singapore?
Colorectal cancer screening is primarily available across public and private hospitals in Singapore.
Many of us may be worried about the cost of health screenings, but thankfully, the government has come up with a slew of financial grants, subsidies and programmes available to offset some of the cost of healthcare.
The Singapore Government has put in place a national screening programme, Screen for Life (SFL), under which subsidised colorectal cancer screenings are provided for Singaporean citizens. Depending on your age, gender, date of last screening, and pre-existing chronic diseases or select cancers, you can access subsidised screenings for colorectal cancer at a low fixed fee.
Colorectal screening is free for Pioneers. CHAS Blue, CHAS Orange and Merdeka Generation (MG) cardholders will only need to pay a fixed fee of $2, while all other Singaporeans, including CHAS Green cardholders, will have to pay $5.
For those of us who would like to have immediate access to colorectal cancer screening, Singapore Cancer Society is also providing Faecal Immunochemical Test (FIT) Kits for FOBT to eligible Singaporean Citizens and Permanent Residents free of charge. Call 1800-727-3333 for further enquiries.
With this knowledge about colorectal cancer screening in Singapore, you are now better equipped to protect yourself and your loved ones against colorectal cancer.
Speak to your doctor or a qualified medical professional today to discuss and decide on which colorectal screening test is most suitable for you and your loved ones and how often you should be going for one. If you want to have personalised health screenings in the comfort of your own home, reach out to our Care Advisors at 6100 0055 to find out how we can help.
- Sung J. J., Ng S.C., Chan F.K., et al. Asia Pacific Working Group (2015). An updated Asia Pacific Consensus Recommendations on colorectal cancer screening. Gut, 64(1), 121–132. https://doi.org/10.1136/gutjnl-2013-306503
- The Singapore Cancer Registry (2019), Singapore Cancer Registry 50th Anniversary Monograph (1968 – 2017) [Ebook]. Retrieved 10 February 2021, from https://www.nrdo.gov.sg/docs/librariesprovider3/default-document-library/thespore-cancerregistry_commerativebook_-1.pdf?sfvrsn=231fce6e_0
- National University Hospital (2020), Screening for Colorectal Cancer [Webpage]. Retrieved 10 February 2021, from https://www.healthhub.sg/live-healthy/106/screening_colorectal_cancer_nuhs
- Mayo Clinic, Colonoscopy [Webpage]. Retrieved 10 February 2021, from https://www.mayoclinic.org/tests-procedures/colonoscopy/about/pac-20393569#:~:text=A%20colonoscopy%20(koe%2Dlun%2D,inside%20of%20the%20entire%20colon.
- American Cancer Society, Can Colorectal Polyps and Cancer Be Found Early? [Webpage]. Retrieved 10 February 2021, from https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/detection.html
- Singapore Cancer Society, FIT Kit [Webpage]. Retrieved 10 February 2021, from https://www.singaporecancersociety.org.sg/get-screened/colorectal-cancer/fit-kit.html
- Mayo Clinic, Barium enema [Webpage]., Retrieved 10 February 2021 from https://www.mayoclinic.org/tests-procedures/barium-enema/about/pac-20393008#:~:text=A%20barium%20enema%20is%20an,rectum%20through%20a%20small%20tube.