Genetic testing for cancer risk is a blood or saliva test that shows whether you carry an inherited change (mutation) in genes such as BRCA1, BRCA2 or the Lynch syndrome genes that raises the risk of cancer; it is different from testing the genes of a tumour [1]. It is recommended for people with triple-negative breast cancer, ovarian cancer, pancreatic cancer, bowel cancer before age 50, prostate cancer that has spread or breast cancer in a man, and for people with particular patterns of cancer in the family [1]. A mutation can be inherited from either the mother or the father, and a positive result opens ways to prevent cancer, find it early and choose treatment [1, 2].
Key points
- Only about 5 to 10 in every 100 cancers are caused by a mutation inherited from a parent [1].
- A test for inherited genes (on blood or saliva) is different from a test of the tumour's genes; the second is used to choose treatment and does not replace the first [1].
- Testing is best started with a family member who has had cancer [1].
- A BRCA or Lynch mutation means a higher risk, not certain cancer. Some carriers of these mutations never develop cancer [2].
- A positive result can be acted on: earlier and closer screening, risk-reducing surgery and testing of relatives; removing the ovaries and fallopian tubes in women with a BRCA mutation cut the risk of ovarian cancer to about a fifth [2, 10].
What is genetic testing for cancer? How a test for inherited genes differs from tumour testing
Genes are the cell's instructions. Some genes, such as BRCA1 and BRCA2, make proteins that repair damaged DNA [2]. If someone has inherited a faulty copy of one of these genes from a parent, their risk of certain cancers is higher; this is called a "hereditary cancer syndrome" [1, 2].
Two kinds of gene test are often confused [1]:
- Testing for inherited genes (germline testing): done on a blood or saliva sample, it finds mutations present from birth in every cell of the body. This is what "genetic testing for cancer risk" means, and the result matters for the family too.
- Testing the tumour's genes (somatic testing): done on tumour tissue, it finds changes that arose in the tumour during life; it is used to choose treatment. It sometimes reveals an inherited mutation as well, but it does not replace a test for inherited genes.
If a tumour test finds a BRCA mutation, it is worth talking to your doctor about a test for inherited genes to find out whether the mutation was inherited [2]. For how much heredity contributes to cancer, see Is cancer hereditary?
Who should have genetic testing for cancer risk?
People who have cancer. Guidelines recommend a test for inherited genes for everyone with these cancers [1]:
- triple-negative breast cancer, or breast cancer in a man;
- ovarian cancer [7];
- pancreatic cancer [8];
- bowel cancer before age 50;
- prostate cancer that has spread [9].
In breast cancer, BRCA1 and BRCA2 testing is offered to everyone diagnosed at age 65 or younger, and to some patients over 65 depending on their family history or whether they might need PARP inhibitor drugs [6]. In bowel cancer and endometrial cancer (cancer of the lining of the womb), a test is usually done on the tumour itself; if it suggests Lynch syndrome, a test for inherited genes is needed [3].
People who do not have cancer but have a family history. These signs make hereditary cancer more likely, and it is worth asking your doctor about genetic counselling [1, 2]:
- a relative has a known inherited mutation;
- cancer at a young age, for example breast cancer at 50 or younger, or bowel cancer before 50;
- several close relatives (parents, brothers and sisters, children) with the same type of cancer;
- breast or ovarian cancer in several people on one side of the family, or bowel cancer and womb cancer in the same family;
- several types of cancer in one person, or cancer in both breasts or both kidneys;
- a rare cancer, such as breast cancer in a man; or ovarian cancer, pancreatic cancer or prostate cancer that has spread in the family.
Before going to genetic counselling, write down which relatives, on your father's side and your mother's side, had which cancer and at what age they were diagnosed. The types of cancer and the ages at diagnosis are among the most important clues to hereditary cancer [1]. If a relative has already been tested, take a copy of their result; your test can then look for exactly that mutation [1].
Which cancers are most linked to family history?
The best-known hereditary cancers fall into two groups [1, 2, 3]:
- BRCA-related cancers: breast cancer (in women and men), ovarian cancer (including cancer of the fallopian tube and peritoneum), pancreatic cancer and prostate cancer [2].
- Lynch syndrome cancers: bowel cancer and endometrial cancer (lining of the womb), and less often cancers of the ovary, stomach, small bowel, urinary tract and kidney, liver and bile ducts, pancreas and brain [3].
Cancer sometimes recurs in a family without any inherited mutation, for example when several people smoke or share the same environment [1].
What are BRCA1 and BRCA2? BRCA1 vs BRCA2
BRCA1 and BRCA2 are two DNA repair genes, and everyone has two copies of each: one from the mother and one from the father [2]. Someone who has inherited one faulty copy still has a healthy copy; but if that healthy copy is damaged in a cell during life, the cell can become cancerous [2]. Carriers of these mutations get cancer more often and at younger ages than other people [2].
Both genes raise the risk of breast cancer by about the same amount [4]. The main difference is that BRCA1 raises the risk of ovarian cancer more, while BRCA2 raises the risk of prostate cancer, breast cancer in men and pancreatic cancer more [2, 4]. Breast cancer in women with a BRCA1 mutation is more often triple-negative [2]; see What do ER, PR and HER2 mean?
| Cancer | BRCA1 | BRCA2 |
|---|---|---|
| Breast cancer in women (by age 80) | About 7 [4] | About 7 [4] |
| Ovarian cancer (lifetime) | 4 to 6 [2] | 1 to 3 [2] |
| Cancer in the other breast, within 20 years of a first breast cancer | About 4 [4] | About 3 [4] |
| Prostate cancer in men (by age 80) | 1 to 3 [2] | 2 to 6 [2] |
| Breast cancer in men (by age 70) | At most about 1 in 100 [2] | 2 to 7 in 100 [2] |
| Pancreatic cancer (lifetime) | Up to 5 in 100 [2] | 5 to 10 in 100 [2] |
For comparison, among all women about 1 in 8 develop breast cancer and about 1 in 100 develop ovarian cancer during their lifetime [2]. Each person's risk also depends on their family history and the location of the mutation [4].
What is Lynch syndrome, and which cancers does it cause?
Lynch syndrome is the most common inherited bowel cancer syndrome, accounting for about 3 in every 100 new bowel cancers [3]. It is caused by a mutation in one of the DNA "mismatch repair" genes, called MLH1, MSH2, MSH6 and PMS2 (and sometimes EPCAM) [3].
- Main cancers: bowel cancer and endometrial cancer; and less often cancers of the ovary, stomach, small bowel, urinary tract, liver and bile ducts, pancreas and brain [3].
- The genes do not carry the same risk: in a study of more than 6,000 carriers, MLH1 and MSH2 carried a high risk of bowel, womb and ovarian cancer; MSH6 mainly raised the risk of womb cancer and raised bowel cancer risk only slightly; and the risk was lowest with PMS2 [5]. Even so, regular colonoscopy is recommended for carriers of all these genes [3].
- The good news: in the same study, more than 8 in every 10 people were alive 10 years after bowel, womb or ovarian cancer [5].
Regular colonoscopy in people with Lynch syndrome has lowered both the number of bowel cancers and deaths from them [3]. For bowel cancer at a young age, see Bowel cancer in young adults.
Is a cancer gene inherited from the mother or the father?
From either. Everyone gets one copy of each gene from their mother and one from their father [2]. With BRCA mutations and Lynch syndrome, one faulty copy is enough to raise the risk [2, 3]. In this type of inheritance, a parent who carries the mutation has a 1 in 2 chance of passing it to each child, and the chance is the same for daughters and sons [3].
Genetic test results: positive, negative or "variant of uncertain significance"
| What the result says | What it means | Next step |
|---|---|---|
| Positive / Pathogenic or Likely pathogenic | A mutation was found that raises the risk of certain cancers; but it does not say whether or when you will get cancer [1, 2] | Genetic counselling, a screening or prevention plan, and testing of relatives [1] |
| Negative, when the family's mutation is already known | You have not inherited the family's mutation; your risk is about the same as everyone else's [1, 2] | Usual screening based on age and family history [1] |
| Negative, when no mutation is known in the family | No mutation was found in the genes tested, but your family history may still raise your risk [1] | Follow-up based on family history; sometimes further testing in the future [1] |
| VUS: Variant of uncertain significance | A change was found, but it is not yet known whether it raises the risk; most turn out to be harmless later [1] | Treatment decisions are not based on it; stay in touch with the laboratory or your doctor so you hear if its meaning becomes clear [1, 6, 7] |
If the result is positive, what lowers the risk?
Women with a BRCA mutation: breast screening
Women with a BRCA mutation: risk-reducing surgery
In a large study, removing the ovaries and fallopian tubes cut the risk of ovarian, tubal and peritoneal cancer to about a fifth and also lowered death from any cause [10]. Removing both breasts before cancer develops cut the risk of breast cancer to about a tenth [11]. These operations cannot be reversed; removing the ovaries before the menopause brings on an early menopause, and no operation brings the risk down to zero [2]. Decide the right timing with your doctor.
Men with a BRCA mutation
Lynch syndrome
Choosing treatment, if you have cancer
For tumours in people with a BRCA mutation, drugs that damage DNA, such as cisplatin, and PARP inhibitor drugs such as olaparib can be effective [2]. See The role of PARP inhibitors in ovarian cancer.
Testing relatives
First- and second-degree relatives (parents, brothers and sisters, children, aunts and uncles, and so on) can be tested for just that mutation [1, 7]. Children under 18 are not usually tested for BRCA, because there is no specific prevention for children and BRCA-related cancer in childhood is very rare [2].
How is genetic testing done?
- 1
Counselling before the test
A doctor or genetic counsellor reviews your own and your family's history, explains which test is suitable and goes through its benefits and limits [1].
- 2
- 3
The result
The result is usually ready in 2 to 3 weeks [1].
- 4
Counselling after the test
Your doctor explains what the result means for you and your family and plans screening or prevention with you [1].
Frequently asked questions
Are home or online genetic tests reliable?
For cancer risk, usually not. Many of these tests do not check all the important changes; for example, one approved home test checks only 3 BRCA mutations and misses about 8 in every 10 cancer-causing BRCA mutations [1]. So a negative result from such a test is not reassuring; have testing arranged by a doctor or genetic counsellor [1, 2].
My result is negative. Does that mean I will never get cancer?
I have a BRCA mutation. Does that mean I will definitely get cancer?
Should men have genetic testing too?
Does genetic testing matter for cancer treatment too?
Might I need to repeat the test?
Inherited genes do not change during life, so a repeat is not usually needed. But if an earlier test checked only a few genes or gave an uncertain result, a more complete test may be suggested in the future [1].
Related pages
- Is cancer hereditary?
- ER, PR, HER2 and Ki-67 on a breast cancer report: what do they mean?
- What is DCIS (stage 0 breast cancer)?
- At what age should you start having mammograms?
- Ovarian cancer treatment: the role of PARP inhibitors and BRCA testing
- Inherited genetic testing in cancer: who, and which genes? (for doctors)
Criteria, risks and risk reduction (for doctors)
For physicians
Who. Breast (ASCO-SSO 2024): BRCA1/2 for all newly diagnosed patients aged 65 or younger and selected patients over 65 (personal or family history, ancestry, or PARP inhibitor candidacy); all patients with recurrent disease who are PARP inhibitor candidates; a second primary cancer in the ipsilateral or contralateral breast; other high-penetrance genes with a supportive family history, and moderate-penetrance genes when needed; a VUS should not change management [6]. Epithelial ovarian (ASCO 2020): germline testing for BRCA1/2 and other susceptibility genes for all, at diagnosis; somatic BRCA1/2 testing if no germline variant; dMMR testing in clear cell, endometrioid and mucinous types; first- and second-degree relatives should be evaluated and tested [7]. Pancreas (ASCO PCO 2019): hereditary risk assessment for all patients with pancreatic adenocarcinoma; germline testing may be discussed even with an unremarkable family history; FPC means two affected first-degree relatives [8]. Prostate (Philadelphia 2019): germline testing in metastatic disease or a suggestive family history; priority genes BRCA2, BRCA1 and MMR [9]. Lynch: universal tumour testing (IHC for MMR proteins or MSI, with BRAF V600E or MLH1 promoter methylation) for all newly diagnosed colorectal and endometrial cancers [3].
Risks. Prospective cohort of 6,036 BRCA1 and 3,820 BRCA2 carriers: cumulative risk to age 80 of breast cancer 72% and 69%, ovarian cancer 44% and 17%, and contralateral breast cancer 20 years after diagnosis 40% and 26%; breast cancer incidence rises rapidly until ages 30–40 (BRCA1) and 40–50 (BRCA2) and then stays at 20–30 per 1,000 person-years [4]. NCI: lifetime ovarian cancer 39–58% (BRCA1) and 13–29% (BRCA2); male breast cancer to age 70 0.2–1.2% and 1.8–7.1%; prostate cancer to age 80 7–26% and 19–61%; pancreatic cancer up to 5% and 5–10% [2]. Lynch (PLSD; 6,350 carriers, 51,646 follow-up years): MLH1 and MSH2 carry high colorectal, endometrial and ovarian risks; older MSH2 carriers have higher risks of upper urinary tract, upper GI, brain and prostate cancer; MSH6 carries a high endometrial and modestly raised colorectal risk; no significantly increased risk was shown for PMS2; 10-year crude survival after colon, endometrial or ovarian cancer over 80% [5].
Risk reduction. BRCA: in 5,783 carriers, bilateral oophorectomy was associated with an 80% reduction in ovarian, tubal or peritoneal cancer (HR 0.20) and, in women without prior cancer, a 77% reduction in all-cause mortality to age 70 (HR 0.23) [10]; bilateral prophylactic mastectomy reduced breast cancer risk by about 90%, and by about 95% with prior or concurrent oophorectomy (PROSE; 483 carriers; breast cancer in 1.9% vs 48.7% of controls at a mean follow-up of 6.4 years) [11]. Earlier breast screening with MRI plus mammography; TVUS and CA-125 have not improved ovarian cancer survival [2]. Prostate screening in BRCA2 carriers from age 40 or 10 years before the youngest diagnosis in the family [9]. Lynch (PDQ table citing NCCN 2024): colonoscopy from age 20–25 for MLH1, MSH2 and EPCAM and from 30–35 for MSH6 and PMS2 (or 2–5 years before the earliest colorectal cancer in the family if it was diagnosed before age 25 or 30, respectively), repeated every 1–2 years (MSH6 and PMS2 every 1–3 years); risk-reducing hysterectomy and salpingo-oophorectomy: among 315 carriers, no cancers in the surgical group versus 33% endometrial and 5.5% ovarian cancer in the non-surgical group; CAPP2: aspirin 600 mg daily (for up to 4 years) reduced colorectal cancer incidence over more than 10 years of follow-up (ITT HR 0.65) [3].
Scientific evidence
Scientific evidence
2 itemsRisks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers
Adjuvant Olaparib for Patients with BRCA1- or BRCA2-Mutated Breast Cancer
Related cancer types
Related questions
References
11 referencesShow all references, 2 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
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- 8Evaluating Susceptibility to Pancreatic Cancer: ASCO Provisional Clinical Opinion
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