Genetic Services for Breast Cancer

Genetic counselling is a service that provides individuals and/or families with information about their personal or familial risks of developing a genetic condition and helps them better understand and manage these implications. 

Our cancer genetic counsellors evaluate medical history and family history of cancer in order to determine the role of genetic factors in an individual’s risk to develop breast or other cancers. Information about genetic testing, cancer screening and management, and familial risks is provided.  

An in-person or by-phone session with one of our genetic counsellors usually consists of:

  • A review of personal medical history and family history
  • An assessment of lifetime risk of breast cancer
  • An assessment of hereditary cancer risks
  • A discussion on hereditary breast and ovarian cancer syndromes
  • A discussion on genetic testing and eligibility
  • A discussion on screening and management options for cancer risk reduction 

Following a genetic counselling session, a patient may be eligible for genetic testing, the High Risk Ontario Breast Screening Program, or both. Family members may be required to have genetic testing too.

Who should consider breast cancer genetic counselling?

Individuals can be referred to our clinic if they have a personal and/or family history of one or more of the following:

  • A first-degree relative who is a carrier of a breast cancer gene mutation
  • Two or more cases of breast cancer and/or ovarian cancer in first or second-degree relatives on the same side of the family
  • Breast cancer at 35 years of age or younger
  • Bilateral breast cancers
  • Both breast and ovarian cancer in the same woman
  • Serous ovarian cancer at any age
  • Male breast cancer at any age
  • Breast and/or ovarian cancer in Ashkenazi Jewish families 

Making an appointment

Your doctor can fax a referral to the Familial Breast Cancer Clinic (Fax: 416-586-1581). If you or your doctor have more questions, please contact us at 416-586-4800 x3244.

Our office will send an appointment date and time to your referring doctor who will then notify you of your appointment. Please contact our office at 416-586-4800 x3244 to confirm the appointment or is you have to reschedule.

Preparing for your appointment

In advance of your appointment, you may want to collect information about your family history. Specifically, our genetic counsellors will be asking about the types and ages at diagnosis of cancer for your relatives. There may be some information you do not know, but any information you provide can be helpful. 

If your appointment is a telephone consultation, you will be called at the number provided on your referral at the date and time of your appointment. Please note, all hospital phone numbers display as private numbers. 

If this appointment is scheduled in person, please arrive 10 minutes prior to your scheduled appointment with your valid OHIP card. The Familial Breast Cancer Clinic is in the main Mount Sinai Hospital building at 600 University Avenue. Take the Murray street elevators to the 12th floor, and check-in at the Marvelle Koffler Breast Centre reception desk. 

Appointments typically take approximately 30-60 minutes.

Genes are the blueprints for the structure and function of our bodies. They are made up of DNA, our genetic material. There are more than 20,000 genes in every cell of our body. We all have two copies of each gene, one of each copy which we inherit from our parents. Sometimes, there can be a disease causing change or “mutation” in a gene that prevents the gene from functioning properly. This may lead to a negative effect on our body and health. Some genes in our body work to prevent cancer from occurring. If there is a mutation in one of these genes, there may be an increased risk for cancer to develop. These mutations can also be inherited or passed down from parent to child. It is important to know that BOTH men and women can carry gene mutations, and both men and women can pass them on to their children

Cancer genetic testing is a laboratory test that “reads” our DNA to search for mutations in genes that can cause a higher risk to develop cancer. . It is important to know that not all breast cancers are hereditary. In fact, most cancers happen sporadically - due to environmental exposures, lifestyle factors, or by chance. It is possible that genetic testing will not show a mutation in the genes tested.

The two most common genes linked to hereditary breast cancer predisposition are the BRCA1 and BRCA2 genes. An inherited mutation in one of these genes increases the risk of breast and ovarian cancer in a woman’s lifetime, and increases the risks of prostate and male breast cancers in men. Other genes have been found that are less common in the population but can also increase the lifetime risk of breast or other cancers. Genetic testing may encompass few or many of these genes, depending on your personal and family history.

A pre-test counselling session to determine eligibility for testing usually occurs on the same day as your consultation in the Familial Breast Cancer Clinic. In Ontario, the Ministry of Health and Long Term Care has specific criteria that outline eligibility for provincially-funded (OHIP funded) genetic testing. Not all people will qualify for genetic testing. If you are interested in genetic testing but do not qualify, you can ask your genetic counsellor for resources such as research studies, or clinically valid/reputable private-pay options for genetic testing. Please note that 23andMe, other ancestry-based genetic testing companies, and third party DNA analysis websites are not clinically trustworthy genetic tests and should not be used for health care management.

Genetic testing involves a simple blood test that is done at Mount Sinai Hospital. There is no special preparation for this blood test (i.e. no fasting). Results can take up to three months, and can be delivered by phone or in-person with your genetic counsellor. Based on your results, our genetic counsellors will provide you with the appropriate next steps or referrals to other health professionals.

There are many factors to consider when deciding if genetic testing is the right step for you. The following are some testing-related considerations to discuss with your genetic counsellor:

  • Understanding the possible causes of your personal or family history of cancer
  • Your personal risks to develop breast, ovarian, or other cancers
  • Determining screening, management, or prevention options
  • Cancer risks for family members
  • Psychosocial impact of knowing mutation carrier status
  • Uninformative or uncertain results of testing

In Ontario, all women between the ages of 50 and 74 are eligible for breast cancer screening (mammogram) every one to two years through the Ontario Breast Screening Program (OBSP) if they have never had a prior breast cancer diagnosis. This is known as Average Risk OBSP

If a woman between the ages of 30-69 is deemed at a higher than general population risk to develop breast cancer after an assessment by a genetic counsellor in our clinic, she may be eligible to be enrolled in the High Risk OBSP. This program provides women with annual mammogram and breast MRIs or ultrasounds. 

Individuals who are eligible for entry into this program are:

  • Known carriers of a gene mutation that puts them at an increased risk for breast cancer
  • First degree relative of a carrier of a gene mutation who has declined genetic testing
  • Assessed as having a greater than 25 percent lifetime risk of breast cancer based on family history (assessment is done by a genetics clinic using IBIS or BOADICEA risk assessment tools)
  • Women who had chest radiation therapy (i.e. as a treatment for Hodgkin’s lymphoma) before the age of 30 and at least 8 years ago

The goal of this program is to detect breast cancers at a stage when they can be effectively treated (i.e. when they are small and have not spread).

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