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Fast Facts - Familial Cancer

Familial Cancer
  • It is estimated that 5 to 10 per cent of all cancers can be explained by a mutation in a high risk cancer gene, inherited from one or both parents

  • Cancers that may be familial include: bowel (colorectal), breast, endometrial (uterine), ovarian, prostate, retinal (eye), kidney, stomach, nervous system, thyroid, melanoma and pancreatic

  • Up to 50 per cent of people who inherit a gene mutation do not develop cancer as a result of that mutation (this varies with the mutation and condition)

  • Those with an inherited mutation can take effective steps to reduce their risk. Screening programs and/or preventative surgery are effective in reducing mortality from familial cancer

  • In South Australia, families can access genetic counselling (assessment and advice) and genetic testing through the Familial Cancer Unit at the Women’s and Children’s Hospital. The service was established in 1998.
Gene mutations associated with an increased risk of some common cancers

BRCA 1 or BRCA 2
  • Associated with an increased risk of familial breast and ovarian cancers
  • Found in about 1 in 1,000 people (about 1 in 100 in people of Jewish descent)
  • Carriers have a 40 to 80 per cent risk of developing breast cancer before the age of 75
  • Carriers have a 10 to 60 per cent chance of developing ovarian cancer before the age of 75
  • Other possible cancers this gene may be associated with include prostate cancer, male breast cancer and pancreatic cancer.

Tp53 (Li Fraumeni Syndrome)
  • Associated with an increased risk of familial breast, bone or soft tissue cancers
  • About 1 in 10,000 people carry this gene
  • Carriers have more than a 50 per cent risk of developing breast cancer before the age of 75
  • Carriers have a 10 to 50 per cent risk of developing bone or soft tissue cancers
  • This gene mutation may be also associated with brain, lung and adrenal gland cancers.

Mismatch Repair Gene (Hereditary Non-polyposis Colorectal Cancer or Lynch Syndrome)
  • Associated with an increased risk of familial bowel and uterine cancers
  • About 1 in 1,000 people carry this gene mutation
  • Carriers have a 50 to 80 per cent risk of developing cancer in the large bowel before the age of 75
  • Carriers have a 40 per cent risk of developing uterine cancer before the age of 75
  • It may also be associated with ovarian cancer and other gastrointestinal renal tract cancers.

APC (Familial Adenomatous Polyposis)
  • Associated with an increased risk of cancer in the large bowel
  • Occurs in about 1 in 10,000 people
  • Carriers have a 90 to 100 per cent risk of developing cancer in the large bowel
  • It may be associated with cancer of the duodenum.

Source
Familial aspects of bowel cancer - a guide for health professionals, Australian Cancer Network (2006).
Advice about familial aspects of breast cancer and epithelial ovarian cancer - a guide for health professionals, National Breast Cancer Centre (2006).
Familial aspects of cancer: a guide to clinical practice, NHMRC (1999)
The genetics file – a resource for general practitioners, Victorian Department of Human Services (2003).




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