The exact reason certain people develop cancer isn’t always known. However, some of the most common risk factors for cancer include:

  • tobacco and alcohol use
  • obesity
  • age

There are also some cancer risk factors you can’t control, such as those that run in your family. This is the case with hereditary breast and ovarian cancer syndrome (HBOC).

Learn more about HBOC syndrome and the inherited genes that increase your risk for cancer, as well as how to reduce your risk of developing HBOC.

Language matters

In this article, we talk about hereditary breast and ovarian cancer syndrome in people who are assigned female at birth. It’s important to note that not everyone assigned female at birth identifies with the label “woman.”

While we aim to create content that includes and reflects the diversity of our readers, specificity is key when reporting on research participants and clinical findings. Unfortunately, the studies and statistics referenced in this article did not include data on, or include, participants who were transgender, nonbinary, transgender, gender nonconforming, genderqueer, agender, or genderless.

Was this helpful?

HBOC syndrome is a type of inherited disorder that increases your risk for breast and ovarian cancers compared to someone without the syndrome. Your risk may also be especially higher before age 50.

Like other inherited cancers, HBOC refers to genetic mutations that are passed on from your parents. Having such genetic mutations from hereditary cancer syndromes doesn’t mean you’ll automatically develop cancer, but your risk is much higher.

Cancer itself develops when genes mutate. However, most cases are acquired, while HBOC and other family syndromes are inherited.

While the exact statistics aren’t known, it’s estimated that 1 out of every 400 to 800 people may have HBOC syndrome.

HBOC syndrome is genetic. Most people with HBOC have inherited genetic mutations in either the BRCA1 or BRCA2 genes. Both men and women can inherit HBOC syndrome.

However, it’s also possible to have HBOC syndrome without mutations in these two genes. Researchers are still studying other possible gene mutations that could contribute to HBOC.

You may also be at a greater risk of HBOC if a close relative, such as a parent or sibling, develops these types of cancer. Also, if a close relative has a BRCA mutation, there’s a 50 percent chance you have the same genetic mutation.

Additionally, BRCA gene mutations are more prevalent in people of Ashkenazi Jewish descent.

Overall, inherited family cancer syndromes account for 5 to 10 percent of all cancer cases. That means that most cancers are notlinked to genetic mutations.

However, if you or a family member has HBOC syndrome, this means you may have abnormal gene changes that increase your risk for breast and ovarian cancers.

According to the Centers for Disease Control and Prevention (CDC), having BRCA mutations may mean you’re up to 65 percent likely to develop breast cancer and up to 39 percent likely to develop ovarian cancer by the age of 70.

Additionally, having HBOC syndrome may increase your risk of developing other cancers, such as:

BRCA1 mutations tend to pose greater risks for breast cancers, while BRCA2 mutations may be linked to prostate, pancreatic, and male breast cancers.

The exact percentages also vary by gene, as follows:

BRCA1 mutationBRCA2 mutationGeneral population
breast cancer (in women)46 to 87%38 to 84%12%
breast cancer (in men)1.2%8.9%0.1%
ovarian cancer39 to 63%16.5 to 27%1 to 2%
pancreatic cancer1 to 3%2 to 7%0.5%
prostate cancer8.9% (before age 65)15% (before age 65)6% (before age 69), with 20 to 25% lifetime risk

Anyone who is considered high-risk for HBOC and has a strong family history should consider getting tested for genetic mutations. This process is also called genetic testing or counseling. It’s conducted via blood or saliva sampling.

HBOC syndrome is identified through genetic testing. This is the only way to determine whether you have genetic mutations that increase your risk for certain cancers. Having this information can help you determine your next steps for risk reduction.

If you’re not sure if HBOC syndrome runs in your family, consider asking your doctor for a referral to genetic counseling, particularly if any of the following factors apply to you or your family:

  • cancers that have occurred in multiple generations of your family
  • personal or family history of multiple types of cancer (such as both breast and ovarian cancers in one person)
  • cancer that affects both organs, including breast cancers affecting both breasts
  • history of cancer occurring at a younger age than usual

Also, if you have a history of HBOC, it may be a good idea to get tested to understand whether you carry genetic mutations, and if there’s a risk of passing them on to children.

While having HBOC syndrome doesn’t mean you will definitely develop cancer, it’s important to consider ways you may reduce your individual risk. Options may include:

  • risk-reducing mastectomy (RRM) for breast cancer prevention (also called a prophylactic, or preventive, mastectomy)
  • risk-reducing salpingo-oophorectomy (RSO) which removes ovaries and fallopian tubes for ovarian cancer prevention
  • chemoprevention, which may involve oral contraceptives to reduce the risk of ovarian cancer or taking tamoxifen, an anti-estrogen treatment to reduce breast cancer cell growth

Your doctor will also likely recommend more frequent testing at a younger age compared with someone who doesn’t have HBOC syndrome. This may include imaging tests, such as mammograms for breast cancer or transvaginal ultrasound for ovarian cancer.

Also, while you can’t change your age or the genes that may increase your risk of cancer development, you can take certain steps, called “protective factors,” to change behaviors and exposures that may increase your cancer risks.

Protective factors against cancer risk

  • maintaining a healthy weight
  • reducing your exposure to chemicals
  • quitting smoking, and avoiding secondhand smoke
  • eating a healthy diet
  • reducing chronic inflammation
  • decreased consumption or avoidance of alcohol
  • avoiding long-term exposure to female hormones or immunosuppressants
Was this helpful?

HBOC syndrome can be passed down on either side of your family, and there isn’t a known way to prevent passing on hereditary cancer syndromes.

Still, even if you have HBOC, research shows that you may decrease your risk of developing related cancers by reducing environmental and behavioral exposure.

Talk with your doctor if you’re concerned about any genetic and acquired risk factors you may have.

HBOC syndrome is caused by inherited genetic mutations that run in families. Having this syndrome may increase your risk for breast and ovarian cancers, as well as other types of cancer, such as those of the prostate and pancreas.

If breast and ovarian cancers run in your family, it may be worth considering genetic testing to determine if you carry genetic mutations that increase your risk of developing these cancers.

While you can’t change your genes, knowing this information can help determine how often and when you should be screened for certain cancers. You can also talk with your doctor about cancer risk factors you may control, such as weight management, smoking, and alcohol use.