Intro
Bowel cancer (also called colorectal cancer) often develops slowly over many years.
Screening aims to detect early cancer — or even pre-cancerous polyps — before symptoms appear. When found early, bowel cancer is far more treatable.
Understanding who should be screened, when to start, and which test is appropriate can significantly reduce risk.
Key Points
- Most bowel cancers develop from polyps over time.
- Screening can detect cancer before symptoms appear.
- The FIT test is commonly used for routine screening.
- Colonoscopy is the most accurate test but is more invasive.
- Family history may require earlier or more frequent screening.
- Symptoms should never be ignored, even if screening is up to date.
Who Should Be Screened?
Average Risk Adults
In many countries, screening begins between ages 45–50 and continues until around 74–75, depending on national guidelines.
People at average risk typically have:
- No personal history of bowel cancer
- No inflammatory bowel disease
- No strong family history of colorectal cancer
Higher Risk Individuals
Earlier or more frequent screening may be recommended if you have:
- A first-degree relative with bowel cancer
- A known genetic syndrome (e.g., Lynch syndrome, FAP)
- Long-standing ulcerative colitis or Crohn’s disease
- A previous history of advanced polyps
Your doctor can assess your personal risk profile.
The FIT Test (Fecal Immunochemical Test)
The FIT test detects small amounts of blood in the stool that are not visible to the eye.
How It Works:
- A small stool sample is collected at home.
- It is analyzed for hidden blood.
- If positive, a colonoscopy is usually recommended.
Advantages:
- Non-invasive
- No bowel preparation
- Convenient
- Suitable for routine screening
Limitations:
- Must be repeated regularly (often every 1–2 years).
- A negative result does not completely rule out cancer.
Colonoscopy
Colonoscopy allows direct visualization of the entire colon using a flexible camera.
How It Works:
- Bowel preparation is required.
- Sedation is typically given.
- Polyps can be removed during the procedure.
Advantages:
- Most accurate screening test
- Allows biopsy and removal of polyps
- Longer screening interval (often 5–10 years if normal)
Risks:
- Small risk of bleeding or perforation
- Requires preparation and sedation
When Should Screening Start?
General guidelines (varies by country):
- Average risk: around age 45–50
- Higher risk: often earlier (sometimes age 40 or younger)
Always follow local health authority guidance or individual medical advice.
Red Flag Symptoms
Screening is for people without symptoms.
If you have symptoms, you should seek medical assessment — even if screening tests are up to date.
Concerning symptoms include:
- Persistent rectal bleeding
- Change in bowel habit lasting more than a few weeks
- Unexplained iron deficiency anemia
- Unintentional weight loss
- Ongoing abdominal pain
These do not always mean cancer — but they require evaluation.
How Screening Prevents Cancer
Most bowel cancers develop from polyps over 7–15 years.
By detecting and removing polyps early, colonoscopy can prevent cancer from developing.
This is why bowel cancer screening is considered one of the most effective cancer prevention strategies.
FAQ
Q: Is the FIT test enough?
A: For average-risk screening, FIT is widely used and effective when repeated regularly. A positive result requires colonoscopy.
Q: If my FIT test is negative, can I ignore symptoms?
A: No. Symptoms should always be assessed by a healthcare professional.
Q: Does screening guarantee I won’t get bowel cancer?
A: No screening test is perfect, but regular screening significantly reduces risk.
Q: Is colonoscopy painful?
A: Most people receive sedation and experience little discomfort.
Further Reading
- National Cancer Institute — Colorectal Cancer Screening
- World Health Organization — Cancer Screening Guidance
- Understanding Bowel Cancer
- Bowel Cancer Survivorship