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Hereditary breast and ovarian cancer syndrome: what it is and what it means | CION Cancer Clinics
Hereditary breast and ovarian cancer syndrome, or HBOC, is an inherited condition that raises the risk of breast, ovarian and a few other cancers. It is usually caused by a fault in the BRCA1 or BRCA2 gene, and it passes through men as well as women. This page explains what HBOC is, which cancers it affects, how it runs in families and what happens once it is found. At CION Cancer Clinics, our oncologists plan screening and care for families with an inherited cancer syndrome, explained in plain words.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What is hereditary breast and ovarian cancer syndrome?
- Which cancers does HBOC make more likely?
- What happens once a family is found to have HBOC?
- The words you will meet, in plain language
- How do BRCA1 and BRCA2 differ?
- What this page cannot tell you
- Four things families tell us about HBOC, and what is true
- Common questions about HBOC
The short answer
What is hereditary breast and ovarian cancer syndrome?
Hereditary breast and ovarian cancer syndrome, usually shortened to HBOC, is an inherited condition that raises the risk of breast and ovarian cancer, and of a few other cancers. It is caused by a faulty gene passed down a family, most often BRCA1 or BRCA2. Having HBOC means a higher risk. It does not mean cancer is certain.
Mostly two genes, sometimes others
BRCA1 and BRCA2 are repair genes. Their normal job is to fix damage in a cell's DNA before it causes trouble. A fault in one of them weakens that repair, so cells in the breast, ovary and elsewhere are more likely to become cancerous over time. A handful of other genes, such as PALB2, can cause a similar family pattern.
How it passes down a family
Everyone has two copies of each gene, one from each parent. A person with HBOC has one faulty copy in every cell of the body. Each of their children has a one in two chance of inheriting it, whether the child is a son or a daughter. A relative who did not inherit the fault cannot pass it on.
Why a name for it helps
Once a family knows it has HBOC, relatives can be tested for the exact fault. Those who carry it can start checks early and plan ahead. Those who do not carry it can usually return to ordinary screening, and that relief is one of the most common results of testing.
HBOC is about risk. It is not a diagnosis of cancer.Where the risk lies
Which cancers does HBOC make more likely?
Breast and ovary are in the name, but the risk reaches further, and it reaches the men in the family too.
Breast cancer in women
The risk is substantially higher than in the general population, and cancers tend to appear at a younger age. Some women develop a second, separate cancer in the other breast years later.
Ovarian cancer
This includes cancers that start in the fallopian tubes and the lining of the abdomen. It is the risk families often underestimate, because there is no reliable screening test for it.
Ovarian cancer in any relative, at any age, is a reason to ask about HBOC.Cancers in men
Men can carry and pass on HBOC without ever being ill. Carriers have a raised risk themselves.
Mainly
- Prostate cancer, sometimes at a younger age
- Breast cancer, which is rare in men otherwise
Pancreas and skin
Pancreatic cancer is more common in HBOC families, especially with BRCA2. Melanoma, a serious skin cancer, is slightly more common with BRCA2 too. Whether any checks are needed depends on who else in the family has been affected.
Not sure whether this applies to you?
Ask an oncologistAfter HBOC is suspected
What happens once a family is found to have HBOC?
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The relative with cancer is tested first
Wherever possible, testing starts with someone who has had breast or ovarian cancer. Their result tells the family whether there is a fault to look for at all, and exactly which one.
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A genetic counsellor explains the result
The counsellor explains what the fault means, which relatives could carry it and what options exist. They also write a letter the family can share with relatives in other cities.
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Relatives are offered a test for that one fault
Parents, brothers, sisters and adult children are tested for the exact fault already found. This is simpler and cheaper than the first test, and it gives a clear yes or no.
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Carriers get a plan made for them
Women who carry the fault usually start breast checks earlier than usual, often with MRI as well as mammograms. Men are advised on prostate checks. Decisions about medicines and preventive surgery come later, with time to think.
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Treatment may change for anyone who already has cancer
A result can open up certain medicines, such as PARP inhibitors, and can change the choice of surgery. This is one reason testing is often done soon after a diagnosis.
On your report
The words you will meet, in plain language
- HBOC
- Hereditary breast and ovarian cancer syndrome. The name of the condition, whichever gene is causing it.
- Pathogenic variant
- A change in the gene known to stop it working. This is what the report means by a fault or a mutation.
- Carrier
- Someone with the faulty gene who does not have cancer. A carrier is healthy and does not need treatment, only a plan.
- Cascade testing
- Testing relatives, one step outward at a time, for the fault already found in the family.
- Risk-reducing surgery
- An operation to remove healthy tissue that has a high chance of becoming cancerous, such as the ovaries and tubes. It is one option, never a requirement.
- Triple-negative
- A type of breast cancer that lacks three common markers. It is more often linked to BRCA1 than other types are.
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Side by side
How do BRCA1 and BRCA2 differ?
BRCA1
BRCA2
Breast cancers are often triple-negative
Breast cancers are usually hormone-sensitive
The higher ovarian cancer risk of the two
A lower ovarian risk, still well above average
Ovarian cancer tends to appear at a younger age
Ovarian cancer tends to appear somewhat later
A smaller raised risk for men
A clearer risk of prostate and male breast cancer
Some raised pancreatic risk
A more marked pancreatic risk
Being straight with you
What this page cannot tell you
It cannot tell you whether your family has HBOC. That needs a genetic counsellor to draw your family tree and, usually, a test on the relative who had cancer. It also cannot give you a personal risk figure. Published numbers vary by gene, by study and by family history, and they are best explained by someone who knows your whole picture.
It cannot read your report
Two people with a BRCA2 result can face quite different situations, depending on the exact variant and how it is classified. A report that says variant of uncertain significance is not a positive result. What your specific variant means is a question for the counsellor who ordered the test.
Who this does not apply to
Most people with one relative diagnosed with breast cancer at an older age do not have HBOC, and most do not need a genetic test. The features that matter are young age at diagnosis, ovarian cancer, breast cancer in a man, triple-negative breast cancer and several affected relatives on one side.
Commonly believed
Four things families tell us about HBOC, and what is true
"HBOC only comes down the mother's side."
It passes through fathers exactly as often as through mothers. A father can carry the fault without any illness and pass it to his daughter, which is why his side of the family tree matters.
"Breast cancer runs in our family, so we must have HBOC."
Most breast cancer is not inherited, and many families with several cases do not carry a single faulty gene. A counsellor looks at ages, types and which side each case sits on.
"A carrier needs surgery straight away."
Nothing needs deciding in a hurry. Checks, medicines and surgery are all options, and many carriers choose different ones at different stages of life.
"Only women need to be tested."
Men carry and pass on HBOC, and have their own raised risks. Leaving brothers and fathers out of testing leaves half the family without answers.
Questions we are asked
Common questions about HBOC
Is HBOC the same as having a BRCA mutation?
Nearly. HBOC is the name of the condition, and a BRCA1 or BRCA2 fault is its most common cause. A fault in certain other genes, such as PALB2, can produce a similar family pattern and is managed in a similar way.
If I carry the fault, will I definitely get cancer?
No. Your risk is substantially higher than average, but many carriers never develop cancer. Those who do are often found early because they were already being checked. Your counsellor can explain what the risk means for you.
Who with cancer should be tested for HBOC?
Testing is usually offered to anyone with ovarian cancer, a man with breast cancer, a woman with breast cancer at a young age or of the triple-negative type, and anyone with a strong family pattern. Your oncologist or counsellor will confirm whether you qualify.
Can ovarian cancer be caught early with screening?
Not reliably. Blood tests and ultrasound have not been shown to find it early enough to make a real difference. That is why removing the tubes and ovaries, once a family is complete, is discussed with carriers.
When should my children be tested?
HBOC does not cause cancer in childhood, and checks do not start in childhood either. Testing usually waits until your child is an adult and can decide for themselves, with counselling first.
Does HBOC change treatment for someone who has cancer?
It can. A result may make certain medicines, such as PARP inhibitors, an option, and it can shape choices about surgery. Your oncologist will explain whether and how it changes your plan.
Will a result affect marriage or insurance?
These are real worries in Indian families. India has no dedicated law on genetic discrimination, and the position on insurance has been argued in court rather than settled by statute. Raise these questions with your counsellor before testing, not afterwards.
Where do I start if I think my family has HBOC?
Write down who had cancer, what kind and at roughly what age, on both sides of the family. Take it to a genetic counsellor or your oncologist. Call the CION helpline if you are unsure who to approach, and someone will point you to the right clinic.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- National Cancer Institute — BRCA Gene Changes: Cancer Risk and Genetic Testing
- GeneReviews (NCBI) — BRCA1- and BRCA2-Associated Hereditary Breast and Ovarian Cancer
- National Cancer Institute — Genetics of Breast and Gynecologic Cancers (PDQ®)–Health Professional Version
- MedlinePlus Genetics — BRCA1 gene
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Recognising HBOC in a family treeThe patterns that point to HBOC, and how to draw your treeWhich genes cause HBOC besides BRCAWhen the pattern fits but BRCA testing is clearHBOC management across a lifetimeWhat the plan looks like at each stage of lifeMen in HBOC familiesWhy the fathers and brothers need testing too
Talk to us
Wondering whether your family has HBOC?
Tell us who in your family had breast, ovarian or prostate cancer, and at what age. We will tell you honestly whether a genetic referral makes sense, and arrange it if it does. One helpline serves every CION centre.