Colorectal cancer is one of the more preventable cancers, largely because it tends to develop slowly—often beginning as small, non-cancerous polyps that can be identified and removed before they become something more serious. Regular screening plays a meaningful role in catching these changes early, when they are most manageable.
In Singapore, there are several screening options available through both public health programmes and private clinics, each with different detection capabilities and preparation requirements. Understanding what is available can help you make an informed decision about the approach that best suits your needs.
How Colorectal Cancer Develops
The colon and rectum’s inner lining continuously regenerates cells. Occasionally, genetic mutations cause cells to grow abnormally, forming small growths called polyps. Most polyps remain benign. However, certain types—particularly adenomatous polyps—carry the potential to develop cancerous changes over time.
This transformation from normal tissue to polyp to cancer typically spans a considerable period. During this window, screening can detect and remove polyps before any malignant changes occur. It can also identify cancers at early stages when treatment outcomes are more favourable.
Location matters in colorectal cancer. Tumours in the right (ascending) colon often grow larger before causing symptoms because the colon is wider in this region and the contents are more liquid. Left-sided and rectal cancers may cause earlier symptoms like blood in stool or changes in bowel habits. This occurs due to the narrower passage and more formed stool. Because bleeding can also stem from benign conditions such as female haemorrhoids, any rectal bleeding warrants proper assessment rather than assumption, as the symptoms can overlap.
Screening Methods Available in Singapore
Faecal Immunochemical Test (FIT)
FIT is a screening tool that detects hidden blood in stool samples. It uses antibodies that specifically identify human haemoglobin (a protein in red blood cells). Unlike older guaiac-based tests, FIT doesn’t react to dietary factors like red meat or certain vegetables. This reduces false positives.
The test requires collecting a small stool sample at home using a provided kit. No dietary restrictions or bowel preparation are needed. Results typically return within a week. A positive result indicates blood was detected and requires follow-up colonoscopy to identify the source—which may be polyps, cancer, haemorrhoids, or other conditions.
FIT is available through Singapore’s Healthier SG Screening for eligible residents.
Colonoscopy
Colonoscopy is both a screening and diagnostic tool. It provides direct visualisation of the entire colon and rectum using a flexible camera-equipped tube. During the procedure, the doctor (gastroenterologist or surgeon) can identify polyps, abnormal tissue, and other lesions. They can simultaneously remove or sample suspicious findings.
The procedure requires thorough bowel preparation the day before. This typically involves a liquid diet and a laxative solution to clear the colon completely. The doctor administers sedation medication to keep you comfortable during the procedure, which typically takes between 30 and 60 minutes, though this may vary depending on individual circumstances. Most people return to normal activities the following day.
Colonoscopy serves dual purposes: it screens for potential issues and allows for therapeutic intervention during the same procedure. The doctor removes the polyps discovered during the examination immediately through the scope. This prevents the need for a separate procedure. The doctor sends tissue samples for analysis by a pathologist (a doctor who examines tissue samples to diagnose disease) to determine if any concerning changes are present.
CT Colonography (Virtual Colonoscopy)
CT colonography is a screening method that uses computed tomography (a specialised X-ray technique) to create detailed images of the colon without inserting a scope. The procedure still requires bowel preparation. The doctor inserts a small tube to gently inflate the colon with air for better visualisation.
If the test detects polyps or abnormalities on CT colonography, a traditional colonoscopy is needed to remove or biopsy the findings. This method may suit individuals who cannot undergo a standard colonoscopy due to certain medical conditions. It may also suit those who prefer a less invasive initial screening approach.
When to Start Screening
Singapore’s Ministry of Health recommends that individuals at average risk begin colorectal cancer screening at age 50. Your healthcare provider can advise on the most appropriate screening method and interval based on your personal risk profile, including age, family history, and existing medical conditions.
? Did You Know?
Polyps removed during colonoscopy cannot become cancerous. This is why colonoscopy is considered both a screening test and a preventive procedure—it may interrupt the cancer development process before malignant changes occur.
Earlier Screening for Higher-Risk Individuals
Certain factors indicate the need for screening before standard age thresholds or more frequent surveillance:
Family history considerations:
- A first-degree relative (parent, sibling, or child) diagnosed with colorectal cancer or advanced polyps at a younger age
- Multiple first-degree relatives with colorectal cancer at any age
- Known hereditary syndromes like Lynch syndrome or familial adenomatous polyposis
Personal medical history:
- Previous colorectal polyps, particularly adenomatous types
- Inflammatory bowel disease (chronic conditions causing inflammation in the digestive tract, such as ulcerative colitis or Crohn’s disease) affecting the colon for an extended period
- Previous abdominal or pelvic radiation therapy
Individuals with these risk factors typically begin colonoscopy screening earlier—often at a younger age or before the youngest affected family member’s diagnosis, whichever comes first. They also undergo repeat examinations at shorter intervals. Your doctor can recommend a personalised screening schedule based on your specific circumstances.
Understanding Your Colonoscopy Results
Colonoscopy findings determine your surveillance schedule. Your surgeon or gastroenterologist will explain your specific findings. They can recommend an appropriate follow-up timeline based on pathology results:
- No polyps found: Repeat colonoscopy in a standard interval for average-risk individuals. FIT may be offered every year or two as an alternative.
- Hyperplastic polyps only: These polyps in the rectum or sigmoid colon carry minimal risk. Standard interval typically applies.
- One or two small adenomatous polyps: Repeat colonoscopy is generally recommended within a few years, depending on polyp characteristics and whether complete removal was confirmed. Your doctor will advise on the appropriate interval.
- Three or more adenomas, or adenomas with certain features: Follow-up colonoscopy in a shorter interval. Features prompting closer surveillance include larger size, villous architecture (a growth pattern with finger-like projections), or high-grade dysplasia (abnormal cell changes that may be precancerous).
- Sessile serrated polyps: These flat polyps require careful monitoring due to their potential to develop into cancer. Surveillance intervals vary depending on size and number.
Preparing for Colonoscopy
The Week Before
Review your current medications with your doctor. Blood thinners may need to be adjusted before the procedure. Specific instructions depend on the medication type and your medical conditions. Diabetic medications also require modification on preparation and procedure days.
Arrange transportation home. Sedation effects persist for several hours after the procedure, making driving unsafe. Plan for someone to accompany you or book appropriate transport.
The Day Before
Switch to a clear liquid diet by morning. Permitted fluids include:
- Water
- Clear broths
- Plain tea or coffee without milk
- Clear juices without pulp
- Sports drinks
Avoid red or purple liquids that can be mistaken for blood during the examination.
Begin the bowel preparation solution as directed—usually in the afternoon or evening. The solution causes frequent loose stools over several hours. Stay near a toilet and keep yourself hydrated with additional clear fluids.
Procedure Day
Complete any remaining preparation solution if instructed. Take only medications your doctor has approved with small sips of water.
At the clinic or hospital, nursing staff will place an intravenous line for sedation. Most colonoscopies use moderate sedation, which keeps you drowsy and comfortable but not fully unconscious. You may have little memory of the procedure afterwards.
⚠️ Important Note
Inform your doctor if you have a pacemaker, artificial heart valve, or history of endocarditis. Antibiotic prophylaxis may be needed before certain procedures.
Reducing Your Colorectal Cancer Risk
Beyond screening, lifestyle factors influence colorectal cancer risk:
- Dietary patterns: Diets emphasising vegetables, fruits, whole grains, and legumes while limiting processed and red meats are associated with lower colorectal cancer incidence. Fibre intake supports healthy bowel function and may reduce prolonged contact between potential carcinogens and the colon lining.
- Physical activity: Regular exercise—aiming for moderate activity on most days—appears protective against colorectal cancer. The mechanisms likely involve improved insulin sensitivity, reduced inflammation, and faster intestinal transit time.
- Body weight: Excess body fat, particularly abdominal obesity, is linked to increased colorectal cancer risk. Maintaining a healthy weight through balanced nutrition and activity contributes to overall cancer prevention.
- Alcohol and tobacco: Both increase colorectal cancer risk. Limiting alcohol consumption and avoiding tobacco products benefits colorectal health alongside numerous other health outcomes.
When to Seek Professional Help
- Blood in your stool (bright red or dark/tarry)
- Persistent change in bowel habits lasting more than a few weeks
- Unexplained abdominal pain or cramping that doesn’t resolve
- Unintended weight loss
- Feeling that your bowel doesn’t empty completely
- New onset of fatigue or weakness without a clear cause
- Narrowing of stool calibre persists over time
- Family member recently diagnosed with colorectal cancer
Commonly Asked Questions
Is a colonoscopy painful?
Sedation is used to help keep you comfortable during the procedure. Most people report feeling nothing or only mild pressure. After the procedure, you may experience bloating from air introduced during the examination. This passes within a few hours.
How accurate is the FIT test?
FIT reliably detects blood in stool. However, not all polyps or early cancers bleed. A negative FIT doesn’t always definitively rule out polyps—it indicates no blood was detected in that sample. This is why regular testing is recommended. Colonoscopy remains the definitive examination for direct visualisation.
Can I request a colonoscopy directly without FIT first?
Yes. Colonoscopy is appropriate as a primary screening method, particularly for those with family history or personal risk factors. Discuss your preferences and risk profile with your doctor to determine an appropriate approach.
What happens if cancer is found during screening?
If the test detects cancer, additional tests determine the extent of disease—typically CT scans of the chest, abdomen, and pelvis. A multidisciplinary team, including surgeons, oncologists, and other doctors, will review your case and recommend a treatment plan tailored to your specific situation. Early-stage colorectal cancers detected through screening have more favourable treatment outcomes.
Are there alternatives for people who can’t complete bowel preparation?
Some individuals have difficulty with standard preparations. Alternative preparation regimens, split-dose protocols, or different preparation solutions may improve tolerability. CT colonography requires preparation but avoids sedation. Discuss challenges with your doctor—solutions often exist.
Conclusion
Start screening at age-appropriate intervals—or earlier if you have family history or risk factors. Colonoscopy may allow for the removal of polyps before cancerous changes develop. FIT testing annually or biannually provides a non-invasive screening option that requires a follow-up colonoscopy if positive.
If you are experiencing any of the above symptoms or are due for colorectal cancer screening, speaking with a Senior Consultant Colorectal Surgeon can help you understand your options.
