Relative(s) with bowel cancer

Non Modifiable Bowel Cancer Australia
 
About 70% of people who develop bowel cancer have no family history of the disease.
 
However, for around 30% of all bowel cancer cases diagnosed there is a family history, hereditary contribution or a combination of both.
 
Generally speaking, the more members of the family affected by bowel cancer, and the younger they were at diagnosis, the greater the chance of a family link.
 
Genetic mutations have been identified as the cause of inherited cancer risk in some bowel cancer–prone families; these mutations are estimated to account for only 5% to 10% of bowel cancer cases overall.

What is my risk of hereditary bowel cancer? 
 
The following may help you and your GP assess your personal risk - 
 
 
High Bowel Cancer Risk
 
Hereditary conditions
 
  • Relatives diagnosed with Familial Adenomatous Polyposis (FAP)
  • Relatives diagnosed with Lynch Syndrome (HNPCC)
  • Siblings of people with MUTYH-associated polyposis (an autosomal recessive condition)

Significant family history of bowel cancer

  • One first-degree and ≥2 first- or second-degree relatives with bowel cancer on the same side of the family, or

  • One first-degree and ≥1 first- or second-degree relatives with bowel cancer on the same side of family in the context of:
    • Multiple bowel cancers in one person
    • Bowel cancer diagnosed under age 50
    • Other HNPCC related cancers 

Moderate Bowel Cancer Risk

Family history of bowel cancer

  • One first-degree relative diagnosed with bowel cancer under age 55, or

  • Two first- or second-degree relatives on the same side of the family diagnosed with bowel cancer at any age
 

Personal health history

  • Bowel cancer
  • Special types of polyps, called adenomas
  • Inflammatory bowel disease such as ulcerative colitis or Crohn's disease

Average or Slightly Above Average Bowel Cancer Risk
 
  • Age 50 or over; and
  • No symptoms to suggest bowel cancer; and
  • No family history, up to those with one affected first-degree relative diagnosed with bowel cancer aged 55 or over 

A first-degree relative can be a parent, brother, sister or child.
A second-degree relative can be an aunt, uncle, grandparent, grandchild, niece, nephew, or half-brother or half-sister. 
 
Modifiable Bowel Cancer Ausralia Screening Surveillance