CRC screening recommendations based on family history

Enter affected first-degree and second-degree relatives to classify Risk Categories 1, 2, or 3 using the NHMRC-approved 2023 family-history recommendations.

Notes on use

Important scope notes before applying the calculated category.

  • This tool is a guide only. Please refer to the most up-to-date guideline or guideline summary.
  • This tool is for asymptomatic patients and does not apply to those with a polyposis or genetic syndrome. It may not apply to those needing screening in families with known syndromes.
  • A first-degree relative is a person’s biological parent, full sibling, or child.
  • A second-degree relative is someone who shares 25% of a person’s genes. It includes grandparents, uncles, aunts, nephews, nieces, grandchildren, half-siblings, and double cousins.

Patient context

Affected relatives

Include colorectal cancer in first-degree relatives and second-degree relatives. Record the age at diagnosis where known.

Relationship Degree Age at CRC diagnosis

Practice points

Guideline practice points to apply when assessing family history.

  • Include both sides of the family when assessing an individual’s risk category for colorectal cancer. Criteria for category 2 and category 3 can be met by inclusion of relatives from both sides of the family.
  • Collecting family history of cancer is often a challenging process and family history is not always reported or recorded accurately.
  • When there is uncertainty about an individual’s family history, they should be encouraged to seek clarification within their family including details on which relatives have had colorectal cancer and their ages at diagnoses.
  • As with all forms of screening for asymptomatic people, those at risk of colorectal cancer should be carefully checked for the presence of symptoms, and appropriate diagnostic investigation completed before entry into a screening program.
Based on Cancer Council Australia, Clinical practice guidelines for the prevention, early detection, and management of colorectal cancer, chapter: Risk and screening based on family history. The guideline recommendations were approved by NHMRC on 28 September 2023. This tool is a decision aid and does not replace clinical judgement.