Who is at increased risk?
A family history of bowel cancer might indicate that there is a faulty gene passed down from generation to generation that increases the risk of developing cancer. Bowel cancer is common, so by chance alone many people will have a relative with such a cancer, and most of the time this will have little implication for others in the family. If, however, the relative is first degree (FDR: brother, sister, mother, father, children), and particularly if he or she was young when affected (< 55 years), then a faulty gene is more likely and this may have important implications for other family members, more so if multiple individuals on the same side of the family are also affected.
Currently, New Zealanders are eligible for a screening colonoscopy on the basis of family history in most public hospitals if:
- One FDR is affected < 55 years of age
- More than one FDR, or a FDR and multiple second degree relatives (SDR: aunt, uncle, grandparents), on the same side of the family are affected at any age.
If you are concerned about your risk of bowel cancer due to it occurring in family members then you should ask your GP for advice. If your family history is complicated then your GP may refer you to the NZ Familial GI Cancer Registry or you may contact them yourself.
Other people that may have an increased risk of bowel cancer include those with longstanding colitis, such as ulcerative colitis or Crohn's disease, and those who have had certain types of polyps found in prior colonoscopies.