Five to 10 per cent of all cancers are due to a genetic predisposition. The features that suggest a genetic predisposition may include:

• early age at onset
• multiple primary cancers
• family history of similar or related cancers.

Up to 15 per cent of invasive ovarian cancers can be explained by an inherited gene fault in BRCA1 or BRCA2 (Cancer Australia 2020b).

In some cases certain pathological subtypes of cancer or tumour tests (immunohistochemistry or tumour genetic tests) may suggest an underlying inherited cancer predisposition.

A familial cancer service assessment can determine if genetic testing is appropriate. Genetic testing is likely to be offered when there is at least a 10 per cent chance of finding a causative ‘gene error’ (pathogenic gene variant; previously called a mutation). Usually testing begins with a variant search in a person who has had cancer (a diagnostic genetic test). If a pathogenic gene variant is identified, variant-specific testing is available to relatives to see if they have or have not inherited the familial gene variant (predictive genetic testing).

It is recommended that all women diagnosed with high-grade serous epithelial ovarian cancer should be offered genetic testing to look for the presence of mutations (e.g. in the BRCA1/2 genes) and should be referred to a familial cancer service (Cancer Australia 2018). The presence of genetic mutations may influence treatment decisions and be relevant to family members.

Medicare funds some genetic tests via a Medicare Benefits Schedule (MBS) item number but most are not. Depending on the personal and family history, the relevant state health system may fund public sector genetic testing.

Pre-test counselling and informed consent is required before any genetic testing. In some states the treating team can offer ‘mainstream’ diagnostic genetic testing, after which referral is made to a familial cancer service if a pathogenic gene variant is identified. The familial cancer service can provide risk management advice, facilitate family risk notification and arrange predictive genetic testing for the family.

Visit the Centre for Genetics Education website for basic information about cancer in a family.

For detailed information and referral guidelines for ovarian cancer risk assessment and consideration of genetic testing, see these resources:

• Cancer Australia’s Genetic testing for women diagnosed with ovarian cancer
• Cancer Australia’s Genetic testing for women diagnosed with ovarian cancer – frequently asked questions (FAQ)