Table 1 ACN Guidelines

Suggested Definition of "Potentially High Risk":

• Three or more first- or second-degree relatives on the same side of the family are diagnosed with bowel cancer.

• Two or more first- or second-degree relatives on the same side of the family are diagnosed with bowel cancer plus any of the following high risk features:

   - multiple bowel cancers in a family member,

   - bowel cancer before age 50 years,

   - a family member who has/had an HNPCC-related cancer (endometrial, ovarian, stomach, small bowel, renal pelvis or ureter, biliary tract, brain cancer)*

• at least one first- or second-degree relative diagnosed with bowel cancer with a large number of synchronous adenomas (suspected FAP),

• there is a member of the family in which a gene mutation that confers a high risk of bowel cancer has been identified.

*The Australian Cancer Network guidelines extend the range of cancers implicated in HNPCC based on subsequent literature identifying other cancers in the syndrome.

Additional tumours for consideration: Breast in hMLH1 families [1], clear cell kidney [2].

Suggested Definition of "Moderately Increased Risk":

• One first-degree relative with bowel cancer diagnosed before age 55 years (without potentially high-risk features).

• Two first- or second-degree relatives on the same side of the family with bowel cancer diagnosed at any age (without potentially high-risk features).