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Genetic Risk Assessment for Hereditary Breast Cancer & Implications

What is Hereditary Breast and Ovarian Cancer (HBOC) syndrome?

About 5 to 10 percent of breast cancers can be attributed to hereditary breast and ovarian cancer (HBOC) syndrome. Genetic change (mutation) in the BRCA1 or BRCA2 gene is the most common cause of HBOC.

Individuals with BRCA1 or BRCA2 mutation tend to develop cancer at an earlier age than the general population and have higher risk for bilateral breast cancer, a second primary tumour in a different tissue, and cancer recurrence.

Mutations in other less common genes have also been found to increase the risk of developing breast and other cancers.

Who might be at risk?

HBOC is an adult-onset, cancer predisposition syndrome which can be passed down through generations.
The history of cancer in your close relatives is a clue about the chance of HBOC syndrome in your family. It is more likely if one or more of the following features can be confirmed in your family:

  • Young age of onset
  • Bilateral breast cancer or personal history of multiple cancers
  • Family history of ovarian, peritoneal, fallopian tube, pancreatic cancers and/or melanoma
  • History of male breast cancer in the family

How is HBOC syndrome diagnosed?

Genetic testing for HBOC syndrome is a blood test that is available at the Cancer Genetics Service at NCCS when specific criteria are met. Genetic testing is complex, thus it does not take place without genetic counselling and the process of informed consent.

What does genetic counselling involve?

Cancer genetic counselling is a process to assess a person's risk of having an inherited susceptibility to cancer. It is usually provided by a genetic counsellor and/or cancer geneticist to help people understand and adapt to the medical, psychological and familial implications of genetic contributions to cancer.

Genetic counselling can help you better understand the outcomes and impacts of genetic testing and the possible implications when finding a genetic mutation of HBOC syndrome.

What can I do to reduce my risk of developing breast or ovarian cancer if I have a BRCA gene mutation?

Increased surveillance (clinical breast exam, mammogram and MRI) and consideration of risk-reducing interventions (such as chemoprevention and preventive mastectomy or oophorectomy) are recommended.

Find out if genetic mutations justify preventive mastectomy.