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Hereditary Breast and Ovarian Syndrome

What is Hereditary Breast and Ovarian Syndrome?

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

Is my family at risk for 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 is not hereditary, only about 5-10% of breast cancers and 10-15% of ovarian cancers are attributed to HBOC.

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.

HBOC syndrome is more likely if one or more of the following features can be confirmed in your family:

  • A woman with breast cancer diagnosed at age 50 or younger.
  • A woman with ovarian/fallopian/peritoneal cancer at any age.
  • A woman with triple negative (ER-,PR-,HER2-) breast cancer diagnosed before age 60.
  • A woman with 2 or more separate breast cancers.
  • A woman with both breast and ovarian cancer.
  • A man with breast cancer.
  • A woman with breast cancer and a close relative with ovarian cancer.
  • 2 or more close relatives with breast cancer, at least one diagnosed at age 50 or younger.
  • There is a history of breast cancer or ovarian cancer and pancreatic cancer or pancreatic cancer on the same side of the family.
  • A person with a known cancer predisposition mutation.
  • Ashkenazi Jewish ancestry.

How is HBOC syndrome diagnosed?

Genetic testing for HBOC syndrome is a blood test that available through the service. 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.

Download the English brochure.

Download the Chinese brochure.

A guide to genetic testing for Hereditary Breast and Ovarian Cancer

Download the English guide here.

Download the Chinese guide here.