Colorectal Cancer Screening

Colorectal cancer often lacks symptoms till later stages.1 It’s important to go for regular screening to detect colorectal cancer early, when it is potentially curable.2 Colorectal cancer screening saves lives.

Who should get screened for Colorectal Cancer?

It is advisable to undergo annual screening from the age of 50, as per national guidelines, even if you display no symptoms and are not classified as high risk. Individuals at high risk might require more frequent and earlier screenings. It’s important to consult your physician for personalised recommendations.2

National Colorectal Cancer Screening Guidelines of Various Countries





and above4





and above3





and above5





and above6

Local guidelines may vary for other countries. For further information and advice, please consult your doctor.

Various methods are available to analyse the colon and rectum for the detection and diagnosis of Colorectal cancer.2

Choosing a screening method depends on your risk profile. Talk to your doctor about your risk profile, when to begin screening, which method is right for you, and how often to get screened.

Screening Methods

Blood-Based Test:7
Circulating tumour DNA (ctDNA) assessment

  • The test evaluates ctDNA mutations, fragment sizes, and DNA methylation associated with cancer.

    • ctDNA refers to DNA that is shed by cancerous cells and tumours

    • DNA methylation refers to a major epigenetic mechanism involving direct chemical modification to the DNA.8

  • A blood test that can be completed during clinic visit.

  • No preparation required.

  • Recommended to be performed every 3 years.

Different tests employ different metholodology and assess different aspects of tumour materials.


  • Detects polyps, cancer; allows removal and biopsy.

  • Full examination of rectum and colon with bowel preparation required before the test. A long, flexible tube with a video camera at the tip is inserted into the rectum.

  • Recommended to be done once every 5 to 10 years.9

CT Colonography (Virtual colonoscopy):1

  • Imaging examination of the colon and rectum using CT scan.10

  • Interpretation by a skilled radiologist is needed for best results. Bowel preparation is required before the test.

  • Recommended to be done every 5 years.10


  • Examines only the rectum and lower colon; polyp/cancer check, removal.

  • Requires a process called enema, where fluids are injected into the rectum to cleanse the colon. A flexible, lighted tube is inserted into the rectum and lower colon.

  • Recommended to be performed every 5 years.10

Stool-Based Test
Faecal Immunochemical Test (FIT):1,10

  • Detects blood in stool; possible sign of polyps/cancer.

  • Recommended to be done yearly.

  • Two stool samples collected over 2 different days required.


All images are actor portrayals only.

This is an educational website on cancer screening. This information should not be used in place of advice from your doctor or other healthcare professional. For further information and advice, please contact your doctor.


1. Colorectal Cancer: Screening. May 2022. Last accessed August 2023. 2. Colorectal Cancer. National University Cancer Institute. June 2021. Last accesssed on Aug 2023. 3. Luu XQ, et al. Acceptance on colorectal cancer screening upper age limit in South Korea. World J Gastroenterol. 2020 Jul 21. 26(27): 3963–3974. 4. Takahashi N, et al. Social-life factors associated with participation in screening and further assessment of colorectal cancer: A nationwide ecological study in Japanese municipalities. SSM Popul Health. 2021 Jun 8;15:100839. 5. Lam TH, et al. Recommendations on prevention and screening for colorectal cancer in Hong Kong. Hong Kong Med J. 2018 Oct;24(5):521-526. 6. Lohsiriwat V, et al. Current Colorectal Cancer in Thailand. Ann Coloproctol. 2020 April. 36(2): 78–82. 7. Chung, et al. Digestive Diseases Week 2023. Abstract #913e. 8. Moore LD, et al. DNA Methylation and Its Basic Function. Neuropsychopharmacology. Volume 38, pages23–38 (2013) 9. Screening for Colorectal Cancer. Health Hub. May 2021. Last Accessed August 2023. 106/screening_colorectal_cancer_nuhs. 10. Julia Yuen SW, et al. Which Colorectal Cancer Screening test should I choose. April 2020. Last Accessed August 2023.

Copyright © Guardant Health 2023