Genomics in general practice

Familial breast and ovarian cancer

Last revised: 30 Nov 2018

Practice point

To identify patients who may be at risk of familial breast and ovarian cancer, a comprehensive family history must be taken and regularly updated.1,2

Refer individuals and families who meet high-risk criteria to a family cancer clinic.

Women who are at average or only slightly higher risk of familial breast and ovarian cancer do not require additional surveillance beyond the National Breast Cancer Screening Program and National Cervical Screening Program nor referral to a family cancer clinic.2
 

Highly penetrant gene variants in BRCA1 and BRCA2 genes are associated with increased risk of several cancers, particularly breast and ovarian. These show autosomal dominant inheritance pattern.1,3 Pathogenic variants in BRCA1 and BRCA2 are associated with increased risk of other cancers including prostate (for men specifically) and pancreatic.

The lifetime risk of breast cancer in Australian women is approximately one in eight.4 Inheriting pathogenic variants of the BRCA1 and BRCA2 genes increase the chance of developing breast cancer to about 70% (cumulative risk to 80 years of age). Despite this, BRCA1 and BRCA2 variants account for only about 5% of all breast cancer cases, because these variants are relatively rare.3–6

Several other genes (low-to-moderate penetrant variants) predisposing to breast and/or ovarian cancer can now also be tested.7

Features within a family that are suggestive of increased risk of carrying a pathogenic BRCA1 or BRCA2 variant include:5

  • multiple affected relatives on the same side of the family (maternal or paternal)
  • breast and ovarian cancer in the same woman
  • breast cancer diagnosed <40 years of age
  • Ashkenazi Jewish ancestry (from central and eastern Europe)
  • bilateral breast cancer
  • male breast cancer.

A three-generation family history is key to identifying high-risk families who are most likely to benefit from genetic testing. Such a history should include first-degree and second-degree relatives on both sides of the family, and ethnic background (eg Ashkenazi Jewish). Note that sex-specific cancer can be inherited through maternal or paternal sides of the family (eg BRCA variants can be passed from the paternal side). Type of cancer (including bilateral) and age of onset should be recorded where available.4

Use existing risk criteria to identify families who are at increased risk of carrying a pathogenic BRCA1 or BRCA2 variant (high risk), or women who may require additional screening or chemoprevention (moderately increased risk).2

Alternatively, the ‘Familial risk assessment – Breast and ovarian cancer’ (FRA-BOC) tool can be used to assess risk .8

Family cancer clinics can assess individual risk to determine the utility of genetic testing for BRCA1 and BRCA2 variants. As new genetic variants predisposing to breast cancer are identified, these new variants may be offered as part of a panel of genetic tests through the family cancer clinic. If a pathogenic variant is identified in an individual, testing will be offered to relatives.4

A rebate is available for BRCA1 and BRCA2 gene testing under the Medicare Benefits Schedule (MBS).9

There is currently no role in general practice for ordering a can cer-risk assessment based on a Single nucleotide polymorphism (SNP) profile (genotyping).

The recommended breast cancer screening strategy for women and different high-risk individuals is outlined in the Royal Australian College of General Pracitioners (RACGP’s) 2016 Guidelines for preventive activities in general practice.2

A cancer antigen 125 (CA 125) blood test and transvaginal ultrasound are not recommended as screening tests for ovarian cancer, even in women who are at high risk.2

Women at increased risk for breast and ovarian cancer should be encouraged to:

  • discuss their family history with all first-degree relatives
  • advise family members to discuss their risk with their general practitioner (GP).

Information

Better Health Channel
Better Health Channel, Genetic testing for inherited cancer
Centre for Genetics Education, Fact sheet 32: Breast and ovarian cancer and inherited predisposition

Support

Breast Cancer Network Australia
Cancer Australia
Cancer Council Australia
Ovarian Cancer Australia
Pink Hope Australia

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