Hereditary Breast and Ovarian Cancer Syndrome

Q: Who is the best person in the family to undergo genetic testing?

Genetic testing is recommended foremostly for the family member whose cancer diagnosis is most suggestive of a hereditary cause (e.g. young or unusual cancer). Those with a history of cancer are more likely to have inherited a faulty gene(s) over those who do not. If a hereditary cause is identified, testing can be subsequently offered to at-risk relatives who do not have cancer or are asymptomatic.

Q: Do males need to be tested?

Genetic testing is recommended for both males and females, as both males and females can inherit faulty gene(s) that increase their risk of cancer. Faulty gene(s) can be inherited from either one’s mother or father. Furthermore, males can pass down the faulty gene(s) to any of their children (sons and daughters).

Q: Is testing recommended for children?

Genetic testing for adult-onset conditions is not recommended for children under the age of 21.Genetic testing in children is only offered when they have a personal history of certain cancers, or if the faulty gene(s) identified in the family is known to increase the risk of cancer during childhood.

Symptoms | Treatments

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What is

Risk Factors

Diagnosis

FAQs

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What is Hereditary Breast and Ovarian Cancer Syndrome?

Hereditary Breast and Ovarian Cancer (HBOC) syndrome is an adult-onset, cancer predisposition syndrome that can be passed down through the family. HBOC syndrome increases the risk of developing breast and ovarian cancers in women, prostate cancer in men, and other cancers such as pancreatic and melanoma.

Common risk factors for cancer

HBOC is primarily associated with a faulty BRCA1 or BRCA2 gene, which increases the lifetime risk of certain cancers.

Lifetime cancer risks for individuals with a faulty BRCA1 or BRCA2 gene
Cancer type	BRCA1	BRCA2	General Population
Breast	47-66%	40-57%	13%
Ovarian	35-36%	13-23%	1-2%
Male Breast	1.2%	~7%	0.1%
Prostate	8.6%	15%	6%
Pancreatic	May be increased	May be increased	<1%
Melanoma	Not increased	May be increased	Up to 2.6%

How Common is HBOC Syndrome?

In Singapore, breast cancer is the most frequent cancer occurring among women: the lifetime risk for breast cancer is around 6%, thus 1 out of 15 women will develop breast cancer. Whereas ovarian cancer is less frequent. However, most breast and ovarian cancer are not hereditary, only about 5-15% of breast cancers and 10-25% of ovarian cancers are attributed to HBOC.

Risk Factors

How is HBOC Syndrome Inherited?

Everyone has two copies of each gene in their body’s cells: one copy from our mother and the other from our father.

HBOC follows a dominant inheritance pattern. This means that having one faulty copy would result in an increased risk of cancer.

How HBOC is genetically inherited

Who Should Undergo Testing for HBOC Syndrome?

The history of cancer in your close relatives is a clue to the chance of HBOC syndrome in your family. Close relatives include: children, brothers and sisters, parents, aunts, uncles, grandchildren and grandparents on one side of the family. A history of cancer in cousins and more distant relatives may also be important.

Individuals who meet, or have family members who meet, one or more of the following criteria can consider genetic testing.

Breast cancer diagnosed at or under 45 years of age
Breast cancer diagnosed at any age in an individual of Ashkenazi Jewish ancestry
Male breast cancer
Multiple primary breast cancers either in one or both breasts
Ovarian cancer
Triple-negative breast cancer before age 60 years
Combination of breast and ovarian cancer
Pancreatic cancer
Metastatic or high-grade prostate cancer (Gleason score ≥ 7)
Two or more relatives on the same side of a family with breast cancer, one under age 50
Three or more relatives on the same side of a family with breast cancer at any age
A previously identified faulty BRCA1 or BRCA2 gene in the family

How Can Your HBOC Genetic Test Result Help You?

Your genetic result may help to personalise your management options based on your cancer risk.

If you have a cancer diagnosis	If you are currently cancer-free
Can help guide important treatment and surgery decisions	Can help guide relevant screening options for you to detect cancer at its earliest, most treatable stage
Indicates what other cancers you are at risk of and how to manage these risks	Can help guide relevant cancer risk-reducing procedures (e.g. surgery)
	Can help you to consider dedicated reproductive options for individuals with HBOC, if you are planning to have children

Diagnosis

Genetic Testing for Hereditary Breast & Ovarian Cancer Syndrome

Genetic testing for HBOC syndrome is a blood test that is available through the Cancer Genetics Service (CGS) at National Cancer Centre Singapore. Genetic testing is complex, thus, individuals interested in testing will undergo genetic counselling to better understand the condition within the family, their personalised cancer risk and the implications of the genetic test.

If your family history of cancer is suggestive of the HBOC syndrome, please talk to your doctor. A referral to the CGS can help you find out more about HBOC syndrome and genetic testing.

How to Manage Your Increased Risk of HBOC if You Are Female

Screening

Breast Cancer
- Annual mammograms and/or breast MRIs
- 6-monthly clinical breast examination
- Practice breast self-awareness
Ovarian cancer
- No effective screening method to detect ovarian
  cancer — risk-reducing surgery is the only recommendation.
Pancreatic cancer
- Endoscopic ultrasonography and/or MRI/magnetic resonance cholangiopancreatography
- Clinical recommendations made on a case-by-case basis
Melanoma (skin cancer)
- Annual skin check by dermatologist
- Clinical recommendations made on a case-by-case basis

Risk-Reducing Surgery

Breast Cancer
- Bilateral mastectomy: surgery to remove breast tissue
- Chemo-prevention drugs (e.g. Tamoxifen) are usually offered on a case-by-case basis to reduce breast cancer risk
Ovarian Cancer
- Bilateral salpingo-oophorectomy: surgery to remove ovaries and fallopian tubes

Lifestyle Adjustments

Pancreatic Cancer: Avoid smoking
Melanoma (skin cancer): Practise sun smart behaviour
All cancers: Keep a healthy diet and an active lifestyle

How to Manage Your Increased Risk of HBOC if You Are Male

Screening

Breast Cancer
- Annual clinical breast examination
- Maintenance of chest awareness and pectoral area palpation on regular basis
Prostate cancer
- Annual digital rectal examination (DRE)
- Annual blood test for prostate-specific antigen (PSA)
Pancreatic cancer
- Endoscopic ultrasonography and/or MRI/magnetic resonance cholangiopancreatography
- Clinical recommendations made on a case-by-case basis
Melanoma (skin cancer)
- Annual skin check by dermatologist
- Clinical recommendations made on a case-by-case basis

Lifestyle Adjustments

Pancreatic Cancer: Avoid smoking
Melanoma (skin cancer): Practise sun smart behaviour
All cancers: Keep a healthy diet and an active lifestyle

Learn more about genetic testing for Hereditary Breast & Ovarian Cancer:

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FAQs

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Genetic testing is recommended foremostly for the family member whose cancer diagnosis is most suggestive of a hereditary cause (e.g. young or unusual cancer). Those with a history of cancer are more likely to have inherited a faulty gene(s) over those who do not.

If a hereditary cause is identified, testing can be subsequently offered to at-risk relatives who do not have cancer or are asymptomatic.

Genetic testing is recommended for both males and females, as both males and females can inherit faulty gene(s) that increase their risk of cancer. Faulty gene(s) can be inherited from either one’s mother or father.

Furthermore, males can pass down the faulty gene(s) to any of their children (sons and daughters).

Genetic testing for adult-onset conditions is not recommended for children under the age of 21.Genetic testing in children is only offered when they have a personal history of certain cancers, or if the faulty gene(s) identified in the family is known to increase the risk of cancer during childhood.

Other Information

Common Myths and Misconceptions

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FALSE. Your genetic test result cannot determine the likelihood of cancer recurrence or the presence of cancer. A positive result only indicates an increased risk of getting cancer or of a new cancer developing.

FALSE. If you have a positive genetic test result, identifying a faulty gene(s), it means each of your children has a 50% (1 in 2) chance of inheriting the faulty gene(s).

FALSE. Genes that govern your appearance are different from cancer protection genes like BRCA1 and BRCA2. All first-degree relatives (siblings, children, parents) have a 50% (1 in 2) chance of inheriting the faulty gene(s) in BRCA1 or BRCA2.

FALSE. Each first-degree relative (parents, siblings, children) has a 50% (1 in 2) chance of inheriting the faulty gene(s). The genetic test result of one brother does not impact the chances for the other brother.

FALSE. The faulty gene(s) can be passed down to and through both males and females. There are increased cancer risks to both males and females. It is therefore important for both females and males to undergo testing to understand if they have inherited the faulty gene(s).

Brothers and sisters who inherit the faulty gene(s) have a 50% (1 in 2) chance of passing it down to their children (daughters and sons).

FALSE. Distant relatives can inherit the faulty gene(s)(e.g. aunties, uncles, cousins). It is important to let them know so they can consider genetic testing to understand their risk of developing cancer.

Download the HBOC guide below: