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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Oncology · Hereditary Breast and Ovarian Cancer syndrome

Understanding Hereditary Breast and Ovarian Cancer (HBOC)

At a Glance

Hereditary Breast and Ovarian Cancer (HBOC) syndrome is an inherited genetic predisposition that increases your cancer risk, often due to BRCA mutations. A mutation is not a cancer diagnosis, but it allows you and your care team to use enhanced screening and preventive measures to protect your health.

Learning that you may have a genetic predisposition to cancer can feel like a heavy weight, but it is important to remember that this information is a tool, not a destiny. Knowledge of your genetic makeup allows you and your medical team to take control of your health through proactive monitoring and personalized prevention strategies [1][2].

Understanding HBOC

Hereditary Breast and Ovarian Cancer (HBOC) syndrome is an inherited condition that increases a person’s lifetime risk of developing certain types of cancer [2]. While most cancers happen by chance or due to lifestyle and environmental factors, HBOC is caused by a specific change (mutation) in your DNA that was passed down from a parent [3][1].

Risk is Not a Diagnosis

The most important distinction to make is that carrying a mutation is not the same as having cancer [1].

  • A Genetic Mutation: This is a “predisposition,” meaning your body’s natural defense system against cancer is slightly less effective than average [1][4].
  • A Cancer Diagnosis: This is the presence of actual cancer cells that require active treatment [1][5].

Many people with these mutations live long, healthy lives without ever developing cancer because they use this knowledge to catch issues early or prevent them entirely [2][1].

The Science of DNA Repair

To understand why HBOC increases cancer risk, it helps to look at how your cells work. Every day, the DNA in your cells gets damaged by normal body processes or the environment. Your body has specialized genes, like BRCA1 and BRCA2, that act as “quality control” workers [6][7].

Normally, these genes produce proteins that fix broken DNA using a highly accurate process called homologous recombination (HR) [6][8]. You can think of this as “copy-pasting” from a healthy backup of your DNA to fix a mistake [9][10].

When someone has a mutation in these genes, they may experience Homologous Recombination Deficiency (HRD) [6]. This means the “quality control” workers can’t do their jobs correctly, allowing DNA errors to pile up over time, which can eventually lead to a tumor [8][7].

Who is Affected?

HBOC can affect anyone, regardless of their background, but it is more common in certain populations due to founder mutations—genetic changes that were passed down through generations within a specific community [11][3].

Population Estimated Prevalence
General Population Roughly 1 in 300 to 1 in 500 people [12][1]
Ashkenazi Jewish Descent Roughly 1 in 40 people (2.5%) [13]

Because the risk is significantly higher in the Ashkenazi Jewish community, doctors often suggest specific screening even if there isn’t a strong family history of cancer [14][11].

Knowledge is Your Greatest Tool

It is completely normal to feel overwhelmed or anxious. However, identifying a mutation before cancer develops provides a window of opportunity that most people don’t get [1][2]. Your care team can now create a custom “roadmap” for you, which may include:

  • Enhanced Surveillance: Using more sensitive tools like breast MRIs or more frequent screenings to catch anything at its earliest, most treatable stage [1][15].
  • Risk-Reduction: Options like preventive surgery or medications that can significantly lower the chance of cancer ever forming [16][17].
  • Targeted Therapies: If cancer is already present, knowing your HRD status helps doctors use specialized treatments like PARP inhibitors, which specifically target and kill cells with these DNA repair flaws [18][8].

Common questions in this guide

What is the difference between having an HBOC mutation and having cancer?
Carrying a genetic mutation means you have an increased risk or predisposition to developing cancer, not that you currently have the disease. Many people with these mutations never develop cancer by using this knowledge for early detection and prevention.
How do BRCA gene mutations increase cancer risk?
Normally, BRCA genes act as quality control workers that repair damaged DNA in your cells. When these genes have a mutation, they cannot fix DNA properly, allowing errors to build up over time which may eventually lead to a tumor.
Who is most at risk for Hereditary Breast and Ovarian Cancer syndrome?
While anyone can have an HBOC mutation, it is significantly more common in certain populations due to genetic changes passed down through generations. For example, people of Ashkenazi Jewish descent have a 1 in 40 chance of carrying a mutation, compared to about 1 in 400 in the general population.
What preventive options are available if I have an HBOC mutation?
If you test positive for an HBOC mutation, your doctor can create a personalized risk-reduction plan. This often includes enhanced surveillance like frequent breast MRIs, targeted medications, or preventive surgeries to lower the chance of cancer forming.

Questions for Your Doctor

5 questions

  • •Based on my family history and ancestry, what are my personal risk estimates for breast and ovarian cancer?
  • •Does my test result show a 'pathogenic variant' or a 'variant of uncertain significance' (VUS), and what does that mean for my care?
  • •If I have a mutation, what specific screening or risk-reduction options (like more frequent MRIs or preventive surgery) do you recommend for me?
  • •Should my siblings, children, or other relatives be tested for this specific mutation?
  • •How does my genetic status affect my treatment options if I am already facing a cancer diagnosis?

Questions for You

3 questions

  • •Have any of my close relatives (parents, siblings, aunts, uncles, grandparents) had breast, ovarian, prostate, or pancreatic cancer, and at what age were they diagnosed?
  • •Am I of Ashkenazi Jewish descent, or do I have other ancestry (like Icelandic or French Canadian) known for specific genetic mutations?
  • •How do I feel about the balance between 'watchful waiting' (frequent screening) versus more proactive preventive surgeries?

References

References (18)
  1. 1

    Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology.

    Daly MB, Pal T, Berry MP, et al.

    Journal of the National Comprehensive Cancer Network : JNCCN 2021; (19(1)):77-102.

    PMID: 33406487
  2. 2

    A dominant RAD51C pathogenic splicing variant predisposes to breast and ovarian cancer in the Newfoundland population due to founder effect.

    Dawson LM, Smith KN, Werdyani S, et al.

    Molecular genetics & genomic medicine 2020; (8(2)):e1070 doi:10.1002/mgg3.1070.

    PMID: 31782267
  3. 3

    Practice Bulletin No. 182 Summary: Hereditary Breast and Ovarian Cancer Syndrome.

    Obstetrics and gynecology 2017; (130(3)):657-659 doi:10.1097/AOG.0000000000002285.

    PMID: 28832475
  4. 4

    Multigene panel analysis identified germline mutations of DNA repair genes in breast and ovarian cancer.

    Hirotsu Y, Nakagomi H, Sakamoto I, et al.

    Molecular genetics & genomic medicine 2015; (3(5)):459-66 doi:10.1002/mgg3.157.

    PMID: 26436112
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    The BRCA Gene in Epithelial Ovarian Cancer.

    Sánchez-Lorenzo L, Salas-Benito D, Villamayor J, et al.

    Cancers 2022; (14(5)) doi:10.3390/cancers14051235.

    PMID: 35267543
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    Women's cancers: how the discovery of BRCA genes is driving current concepts of cancer biology and therapeutics.

    Murthy P, Muggia F

    Ecancermedicalscience 2019; (13()):904 doi:10.3332/ecancer.2019.904.

    PMID: 30915162
  7. 7

    Therapeutic targeting and patient selection for cancers with homologous recombination defects.

    Talens F, Jalving M, Gietema JA, Van Vugt MA

    Expert opinion on drug discovery 2017; (12(6)):565-581 doi:10.1080/17460441.2017.1322061.

    PMID: 28425306
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    Homologous recombination proficiency in ovarian and breast cancer patients.

    Creeden JF, Nanavaty NS, Einloth KR, et al.

    BMC cancer 2021; (21(1)):1154 doi:10.1186/s12885-021-08863-9.

    PMID: 34711195
  9. 9

    The Role of PALB2 in the DNA Damage Response and Cancer Predisposition.

    Nepomuceno TC, De Gregoriis G, de Oliveira FMB, et al.

    International journal of molecular sciences 2017; (18(9)) doi:10.3390/ijms18091886.

    PMID: 28858227
  10. 10

    BRCA1/2 signaling and homologous recombination deficiency in breast and ovarian cancer.

    Royfman R, Whiteley E, Noe O, et al.

    Future oncology (London, England) 2021; (17(21)):2817-2830 doi:10.2217/fon-2021-0072.

    PMID: 34058833
  11. 11

    Evaluation of genetic alterations in hereditary cancer susceptibility genes in the Ashkenazi Jewish women community of Mexico.

    Díaz-Velásquez CE, Gitler R, Antoniano A, et al.

    Frontiers in genetics 2023; (14()):1094260 doi:10.3389/fgene.2023.1094260.

    PMID: 36845387
  12. 12

    Breast and Ovarian Cancer Penetrance Estimates Derived From Germline Multiple-Gene Sequencing Results in Women.

    Kurian AW, Hughes E, Handorf EA, et al.

    JCO precision oncology 2017; (1()):1-12 doi:10.1200/PO.16.00066.

    PMID: 35172496
  13. 13

    Population-Wide Screening for Germline BRCA1 and BRCA2 Mutations: Too Much of a Good Thing?

    Yurgelun MB, Hiller E, Garber JE

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2015; (33(28)):3092-5 doi:10.1200/JCO.2015.60.8596.

    PMID: 26282646
  14. 14

    Exome Sequencing-Based Screening for BRCA1/2 Expected Pathogenic Variants Among Adult Biobank Participants.

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    JAMA network open 2018; (1(5)):e182140 doi:10.1001/jamanetworkopen.2018.2140.

    PMID: 30646163
  15. 15

    The Role of Risk-Reducing Surgery in Hereditary Breast and Ovarian Cancer.

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    The New England journal of medicine 2016; (374(5)):454-68 doi:10.1056/NEJMra1503523.

    PMID: 26840135
  16. 16

    Biological and clinical evidence for somatic mutations in BRCA1 and BRCA2 as predictive markers for olaparib response in high-grade serous ovarian cancers in the maintenance setting.

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  17. 17

    BRCA1/2 mutations and risk-reducing bilateral salpingo-oophorectomy among Latinas: The UPTAKE study.

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    Journal of genetic counseling 2021; (30(2)):383-393 doi:10.1002/jgc4.1322.

    PMID: 33010199
  18. 18

    Targeting the DNA Repair Enzyme Polymerase θ in Cancer Therapy.

    Schrempf A, Slyskova J, Loizou JI

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    PMID: 33109489

This page provides educational information about Hereditary Breast and Ovarian Cancer (HBOC) syndrome and genetic risk. It does not replace professional medical advice from your genetic counselor or oncologist.

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