Relative(s) with bowel cancer

About 75% of people who develop bowel cancer have no family history of the disease.
 
However, for around 25% 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 6% of bowel cancer cases overall.
 
Risk Family History 770new
 

 
What is my risk of hereditary bowel cancer? 
 
The following guidelines from the Gastroenterological Society of Australia (GESA) may help you and your GP assess your personal risk - 
 
  • Potentially High Risk
    Risk of developing bowel cancer increases 15-fold
    • 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 individual
      • bowel cancer <50 years
      • the presence of other HNPCC-related cancers, which includes gastric, small intestinal, endometrial, ovarian, ureter, renal pelvis, biliary tract, pancreas and brain
    • Relatives diagnosed with an autosomal dominant inherited bowel cancer syndrome, such as HNPCC or familial adenomatous polyposis (FAP)
    • Siblings of patients with MUTYH-associated polyposis (an autosomal recessive condition)
 
  • Moderately Increased Risk
    Risk of developing bowel cancer increases 3-6 fold
    • One first-degree relative diagnosed with bowel cancer < 55 years, or

    • Two first- or second-degree relatives (on the same side of the family) diagnosed with bowel cancer at any age.
 
  • Slightly Above Average Age-Specific Risk
    Risk of developing bowel cancer increases up to 2-fold
    • Includes patients with no family history up to those with one affected first-degree relative diagnosed ≥55 years.  

      Whilst patients with one affected first-degree relative (≥55 years) have up to twice the average risk of bowel cancer, this is not sufficient to warrant more intensive screening.
 
* A first-degree relative can be a parent, sibling or child.
 
 
Bowel Cancer Australia Helpline
Banner Bowel Cancer Australia Screening Surveillance 300
Banner Bowel Cancer Australia Non Modifiable Risk Factors 300