Hereditary cancer: a complete guide to inherited cancer risk
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Hereditary cancer is cancer that develops in someone who has inherited a gene variant linked to a higher chance of certain cancers, such as a variant in BRCA1, BRCA2 or one of the Lynch syndrome genes. Inherited variants play a part in about 5–10% of all cancers.1 They do not cause cancer on their own and they do not make it inevitable; they increase the likelihood that cancer may develop over a lifetime. Hereditary cancer testing can find these variants before cancer appears, which gives people the chance to prevent many of these cancers or find them early, when treatment works best.
Key takeaways
- About 5–10% of cancers involve an inherited gene variant, which can be passed down from either parent.
- Inherited variants increase the chance of certain cancers but do not cause cancer on their own, and many people who carry one never develop cancer.
- Someone can carry a variant with no symptoms and no obvious family history of cancer.
- In an Australian study of more than 10,000 young adults, about 1 in 50 carried a variant linked to a higher, but reducible, risk of cancer or heart disease.
- Many hereditary cancers can be prevented or found early, and prevention measures are even more valuable for people who carry a variant.
What is hereditary cancer, and how common is it?
Most cancers develop by chance. As cells divide over a lifetime, they gradually pick up small genetic changes, and factors such as smoking, alcohol, diet, excess weight, sun exposure and ageing all add to that everyday wear and tear. Cancers that arise this way are called sporadic, and they make up the large majority of cases. A smaller share, about 5–10%, are described as hereditary, because the person was born with a gene variant that makes some of the body’s natural protection against cancer less robust. Finding these inherited variants before cancer has a chance to develop is the purpose of hereditary cancer testing.
Genes work like instruction manuals for the body’s cells, and everyone’s instructions differ slightly from everyone else’s. Most of these differences, called variants, make no difference to health at all. A small number, however, sit in genes whose job is to repair damaged DNA or keep cell growth in check. Because each person has two copies of these genes, someone who inherits a variant in one copy usually still has a second working copy, which is one reason cancer is not inevitable. What changes is the margin for error, since fewer additional changes are needed over a lifetime for a cell to become cancerous. On a genetic report, these are described as “pathogenic” or “likely pathogenic” variants, the clinical terms for variants with strong evidence linking them to increased risk. Our guide to understanding your genetic test report explains these terms.
How is hereditary cancer passed on in families?
Most inherited cancer variants are passed on in a dominant pattern, so each child of someone who carries a variant has a 50% chance of inheriting it.2 The variant can come from either the mother or the father, so a father’s family history of breast or ovarian cancer matters just as much as a mother’s.
[Insert inheritance diagram. Caption: “How most inherited cancer variants are passed on: from either parent, with a 50% chance for each child.”]
The best-known examples are variants in the BRCA1 and BRCA2 genes, which are associated with hereditary breast and ovarian cancer, and variants in the Lynch syndrome genes (MLH1, MSH2, MSH6, PMS2 and EPCAM), which are associated mainly with bowel and uterine cancer. According to eviQ, the Cancer Institute NSW’s clinical guidelines for cancer genetics, about 11% of Australian women will develop breast cancer by age 80. For women with a BRCA1 variant, that figure is about 72%, and for women with a BRCA2 variant it is about 69%. Ovarian cancer risk also rises, from less than 1% in the general population to about 44% with a BRCA1 variant and 17% with a BRCA2 variant.2 These figures reflect a real increase in risk, yet they also show that many people with these variants never develop cancer, and that the right screening and prevention can shift the odds further in favour of health and longevity. Prevonco, Genotype Health’s cancer genetic screen, looks for variants in BRCA1, BRCA2 and all five Lynch syndrome genes, along with many other genes linked to inherited cancer risk, so people can find out where they stand and plan ahead.
What are the signs of hereditary cancer in a family?
Certain family patterns can suggest that an inherited variant may be present. These include several relatives on the same side of the family with the same or related cancers, cancer diagnosed at a younger age than usual (for example, breast or bowel cancer before 50), one person who has had more than one separate cancer, cancer in both of a paired organ such as both breasts, or a less common cancer such as ovarian, pancreatic or male breast cancer.
However, the absence of these patterns does not rule out an inherited variant. Families may be small, medical histories are often incomplete or not shared, and variants can travel quietly through a family for generations without any signs being picked up. As a result, many people who carry a variant have no warning at all, which is exactly why proactive screening is so valuable.
Australian research shows how common this is. In DNA Screen, a national study led by Monash University that offered free genetic screening to more than 10,000 Australians aged 18 to 40, about half of the people found to carry a variant linked to hereditary breast and ovarian cancer or Lynch syndrome had no history of cancer in a close blood relative such as a parent, brother or sister.3
How is hereditary cancer tested for, and who should be tested?
Hereditary cancer is tested for with a genetic test that looks for variants in genes linked to cancer risk. This is arranged either through the public system, for people who have had cancer or have a strong family history, or as a proactive screen for healthy adults.
What a genetic result makes possible
Proactive screening allows healthy people to learn about an inherited predisposition before cancer has a chance to develop. Because a variant signals increased risk rather than disease, hereditary cancer testing opens a window of time in which to act. Working with a doctor and genetic counsellor, someone who carries a variant can build a personalised plan that matches screening and prevention to their actual level of risk, rather than to population averages that may not reflect their profile.
The benefits also reach beyond the individual. Parents, brothers, sisters and children each have a 50% chance of sharing the same variant, so one person’s result can help a whole family understand its risk. Through Family Variant Testing, which Genotype Health offers on referral from our genetic counsellors, relatives can check for the specific variant already identified. Those who share it can start prevention early, while those who don’t can usually continue with standard population screening.
“An inherited variant isn’t a diagnosis, and there’s no need for anyone to feel guilty or ashamed. It’s information that gives people a head start. When we know which gene is involved, we can tailor screening and prevention to a person’s real level of risk, often years before anything would show up. Our aim is to empower people, not to alarm them.”
Dr Mona Saleh, Head Genetic Counsellor, Genotype Health
Preventing hereditary cancer
For many hereditary cancers, the answer is yes, cancer can be prevented, and the evidence is strong. The options depend on the gene involved, which is why knowing the specific variant matters so much.
In people with Lynch syndrome, regular colonoscopy allows small growths called polyps to be found and removed before they ever become cancer. A landmark 15-year Finnish study found that colonoscopy every three years reduced bowel cancer cases by 62% in families with Lynch syndrome, and no one in the screened group died from bowel cancer.4 More recently, the international CAPP2 trial found that taking aspirin daily for about two years lowered bowel cancer risk by around a third over the following decade, although aspirin should only be started on medical advice.5
For women with a BRCA1 or BRCA2 variant, options include breast MRI and mammography from a younger age, medication that lowers breast cancer risk, and risk-reducing surgery. In a large international study of almost 5,800 women, removing the ovaries and fallopian tubes lowered the risk of ovarian cancer by 80% and lowered the overall risk of death by 77%.6 Risk-reducing mastectomy lowers breast cancer risk by about 90%.7 These are personal choices rather than requirements, and the timing often depends on age and family plans, so genetic counselling and consultation with a specialist help each person weigh the options against their own circumstances and values.
Everyday habits matter, and they may matter even more for someone who carries a variant. Cancer Australia estimates that about one third of Australia’s cancer burden is linked to factors such as tobacco, physical inactivity, excess weight, alcohol and low fruit and vegetable intake.8 Research in people with Lynch syndrome shows how this plays out alongside inherited risk: in the CAPP2 study, people living with obesity were more than twice as likely to develop bowel cancer as those in the healthy weight range.9 Because inherited and lifestyle risks add together, reducing the ones within reach can make a bigger real-world difference for someone who starts from a higher baseline.
“A gene variant is only one part of the picture. What people do with that knowledge, from keeping up with screening to not smoking and staying active, has a real influence on whether cancer ever develops. For someone with an inherited variant, prevention isn’t less important. It’s more important.”
Dr Matt Edwards, Clinical Geneticist, Genotype Health
Government-funded testing in Australia
In Australia, people with a strong family history of cancer can be referred, usually by their GP, to a public family cancer clinic (also called a cancer genetics service). These state-funded services assess personal and family history, provide genetic counselling, and arrange genetic testing when the chance of finding a variant is high enough, generally 10% or more.3 Medicare also covers genetic testing in specific situations when it is requested by a specialist. These include people who have already been diagnosed with breast, ovarian, fallopian tube or primary peritoneal cancer and whose personal and family history gives them a greater than 10% chance of carrying a variant; some people with bowel or uterine cancer whose tumour testing or history suggests Lynch syndrome; and relatives of someone already known to carry a variant in genes such as BRCA1 and BRCA2.10 This means that people who have not had cancer themselves, and who have no known variant in their family, usually do not qualify for government-funded testing, even if they carry a variant. The Centre for Genetics Education keeps an up-to-date list of public cancer genetic services in each state and territory for anyone who would like to find out more or discuss a referral with their GP.11 See also Medicare funding for genetic testing in Australia.
Published in Nature Health in 2026, DNA Screen tested young adults for variants in ten genes linked to hereditary breast and ovarian cancer, Lynch syndrome and familial hypercholesterolaemia (an inherited cause of high cholesterol and early heart disease). Of the 10,263 people screened, 202, or about 1 in 50, carried a variant linked to a higher risk of one of these conditions, each of which can be prevented or managed when it is found early. Importantly, 82 of the 113 people found to carry a variant linked to hereditary breast and ovarian cancer or Lynch syndrome (nearly three in four) would not have qualified for government-funded genetic testing under current criteria. Almost everyone referred for follow-up care (98%) chose to take it up.3 Together, these findings suggest that many Australians with an inherited cancer risk are currently going undetected, and that people welcome the chance to act on this information when it is offered to them.
Proactive screening with Genotype Health
Genotype Health offers two proactive screens for hereditary cancer risk. Prevonco is a focused 83-gene cancer screen for people who want a clear picture of their inherited cancer risk. Omnagen is a broader 181-gene health screen that covers inherited cancer risk alongside other medically actionable adult-onset conditions, such as inherited heart, neurological and metabolic diseases. Both include the key cancer-susceptibility genes, including those linked to hereditary breast and ovarian cancer, Lynch syndrome, familial adenomatous polyposis and many other inherited cancer predispositions.
Ancestry matters more than the number of genes on a test. Many hereditary cancer panels were built mainly from European genetic datasets, and because the frequency and range of cancer-related variants differ between populations, these panels can miss variants that are more common in other communities (see genomic equity). For this reason, Genotype Health offers tailored panels for Southeast Asian (SEA), Middle Eastern and North African (MENA) and Ashkenazi Jewish communities. These panels use the same core genes as Prevonco and Omnagen but add variants that are more common in each population, giving a more accurate and complete picture of inherited risk.
Who should consider screening
These screens are designed for healthy adults aged 18 and over who want to understand their inherited cancer risk or who simply want more clarity about their future health. People whose families show some of the patterns described above, or who already know of an inherited variant in the family, should speak with a genetic counsellor first, because targeted diagnostic testing for the specific family variant may be more appropriate than a broad screen.
This is a proactive screen rather than a diagnostic test. It isn’t intended for people who currently have symptoms of cancer or an existing diagnosis, who should see their doctor or oncologist for clinical assessment and diagnostic genetic testing. For everyone else, the screens can be ordered online without a doctor’s referral.
How the testing process works
Getting started with hereditary cancer testing through Genotype Health is simple. The Prevonco and Omnagen product pages explain which screen suits which needs, and the process begins with a pre-test consultation with Tara, Genotype Health’s AI assistant, which explains some general information about genetic testing and how it can help you make informed choices about your health. Tara then collects information about you and your family’s medical history, and will escalate to one of our team to contact you if a more appropriate test is indicated. Once an order is placed, a home collection kit arrives by post, and it needs only a quick, painless cheek (buccal) swab. Results are delivered securely online, usually within about four weeks.
If a variant linked to increased risk is found, Genotype Health’s genetic counsellors explain what it means for that person and their family, discuss medical follow-up and prevention options, and consider whether Family Variant Testing could help relatives. Understanding inherited risk early isn’t about fear. It’s about having the knowledge to make confident, proactive decisions about prevention, early detection and long-term health.
Ready to take the next step?
Understand inherited cancer risk with a proactive screen: Explore Prevonco or Explore Omnagen.
Not sure which test fits, or is there cancer in the family? Speak to a genetic counsellor.
Explore this topic
- Proactive health genetic screening: a complete guide
- DNA Screen: what Australia’s national genetic screening study found
- Family variant testing: what to do when a relative has a confirmed genetic finding
- Genetic testing and your insurance
- Everything you need to know about genetic testing and counselling
What else do people ask about hereditary cancer?
Can hereditary cancer risk be inherited from a father?
Yes. These variants, including those in BRCA1 and BRCA2, can be passed down by either parent to sons and daughters alike.
Does a BRCA or Lynch syndrome variant mean I will definitely get cancer?
No. These variants increase the chance of certain cancers developing, but many people who carry them never develop cancer. Evidence-based screening, risk-reducing options and healthy habits can lower the risk further.
Can I have a hereditary cancer variant with no family history?
Yes. Small families, incomplete medical records and inheritance through either parent all mean someone can carry a variant without any obvious family history of cancer. In Australia’s DNA Screen study, about half of the young adults found to carry a variant linked to hereditary breast and ovarian cancer or Lynch syndrome had no history of cancer in a close relative.
Can hereditary cancer be prevented?
Many hereditary cancers can be prevented or found early. Depending on the gene involved, options include earlier and more frequent screening such as colonoscopy or breast MRI, risk-reducing medication or surgery, and lifestyle measures such as not smoking, limiting alcohol and staying active.
What is the difference between Prevonco and Omnagen?
Prevonco is an 83-gene screen focused on inherited cancer risk. Omnagen is a broader 181-gene screen that covers inherited cancer risk plus other medically actionable adult-onset conditions, such as inherited heart, neurological and metabolic diseases.
Is genetic testing for hereditary cancer covered by Medicare?
Medicare covers genetic testing in specific situations, mainly for people who have already been diagnosed with certain cancers and meet family history criteria, and for relatives of someone known to carry a variant. People with a strong family history can also be referred by their GP to a public family cancer clinic, which may provide some tests for free, depending on local protocols. Healthy people with no known variant in their family usually do not qualify, which is where proactive screening such as Prevonco can help.
Do I need a doctor’s referral for hereditary cancer testing?
No. Prevonco and Omnagen can be ordered online without a referral, starting with a pre-test consultation through Tara, our AI assistant. Any result showing increased risk is supported by expert genetic counselling.
References
- National Cancer Institute. Genetic testing for inherited cancer risk [Internet]. Bethesda (MD): National Cancer Institute; 2024 [reviewed 2024 Apr 18; cited 2026 Sep 27]. Available from: https://www.cancer.gov/about-cancer/causes-prevention/genetics/genetic-testing-fact-sheet
- Cancer Institute NSW. BRCA1 or BRCA2 – risk management (female). eviQ protocol ID 3814, version 5 [Internet]. Sydney: Cancer Institute NSW; 2025 [updated 2026 Feb 23; cited 2026 Sep 27]. Available from: https://www.eviq.org.au/cancer-genetics/adult/risk-management/3814-brca1-or-brca2-risk-management-female
- Lacaze P, Tiller J, Brotchie A, Nguyen-Dumont T, Steen J, Belluoccio D, et al. Feasibility and outcomes of the DNA Screen nationwide adult genomic screening pilot. Nat Health. 2026;1(1):90–8. doi:10.1038/s44360-025-00020-x
- Järvinen HJ, Aarnio M, Mustonen H, Aktan-Collan K, Aaltonen LA, Peltomäki P, et al. Controlled 15-year trial on screening for colorectal cancer in families with hereditary nonpolyposis colorectal cancer. Gastroenterology. 2000;118(5):829–34. doi:10.1016/S0016-5085(00)70168-5
- Burn J, Sheth H, Elliott F, Reed L, Macrae F, Mecklin JP, et al. Cancer prevention with aspirin in hereditary colorectal cancer (Lynch syndrome), 10-year follow-up and registry-based 20-year data in the CAPP2 study: a double-blind, randomised, placebo-controlled trial. Lancet. 2020;395(10240):1855–63. doi:10.1016/S0140-6736(20)30366-4
- Finch AP, Lubinski J, Møller P, Singer CF, Karlan B, Senter L, et al. Impact of oophorectomy on cancer incidence and mortality in women with a BRCA1 or BRCA2 mutation. J Clin Oncol. 2014;32(15):1547–53. doi:10.1200/JCO.2013.53.2820
- Rebbeck TR, Friebel T, Lynch HT, Neuhausen SL, van ’t Veer L, Garber JE, et al. Bilateral prophylactic mastectomy reduces breast cancer risk in BRCA1 and BRCA2 mutation carriers: the PROSE Study Group. J Clin Oncol. 2004;22(6):1055–62. doi:10.1200/JCO.2004.04.188
- Cancer Australia. Lifestyle risk factors and the primary prevention of cancer: impact of cancer [Internet]. Surry Hills (NSW): Cancer Australia; 2025 [cited 2026 Sep 27]. Available from: https://www.canceraustralia.gov.au/resources/position-statements/lifestyle-risk-factors-and-primary-prevention-cancer/impact-cancer
- Movahedi M, Bishop DT, Macrae F, Mecklin JP, Moeslein G, Olschwang S, et al. Obesity, aspirin, and risk of colorectal cancer in carriers of hereditary colorectal cancer: a prospective investigation in the CAPP2 study. J Clin Oncol. 2015;33(31):3591–7. doi:10.1200/JCO.2014.58.9952
- Australian Government Department of Health, Disability and Ageing. Medicare Benefits Schedule: items 73296, 73297 and 73354 [Internet]. Canberra: Department of Health, Disability and Ageing; [cited 2026 Sep 27]. Available from: https://www.mbsonline.gov.au
- Centre for Genetics Education. Public cancer genetic services Australia [Internet]. Sydney: NSW Health Education and Training Institute; 2025 Sep [cited 2026 Sep 27]. Available from: https://www.genetics.edu.au/PDF/Public_cancer_genetic_services_Australia.pdf
