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Study: Genetic testing among people with cancer can find mutations that may affect treatment and prevention


Despite national guidelines recommending genetic testing, less than 10 percent of eligible patients had genetic testing within two years after their cancer diagnosis. Among those who had testing, 10-30 percent had an inherited mutation that could affect their medical care. (Posted 3/15/2024)

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Genetic testing among people with cancer can find mutations that may affect treatment and prevention
Glossary on


Most relevant for: People diagnosed with cancer who have not yet had genetic testing.
It may also be relevant for:

  • people newly diagnosed with cancer
  • people with a family history of cancer
  • people with metastatic or advanced cancer

Relevance: High

Strength of Science: High

Research Timeline: Post Approval

Relevance Rating Details

What is this study about?

This study looked at whether people diagnosed with cancer who meet the guidelines for genetic testing are actually tested.

Why is this study important?

Genetic testing can help people and their doctors decide the best course of cancer treatment. When a person has an in a gene that increases their risk of cancer, they are said to have . Targeted treatments such as PARP inhibitors and drugs may work particularly well for treating some hereditary cancers. Genetic testing can also help people learn their risk for a new cancer diagnosis. Knowing one’s genetic status may be useful for family members, including siblings, children or parents who may also be at risk.

Study findings

This study looked at information from the Surveillance, Epidemiology and End Results () national registry that tracks cancer cases. The researchers reviewed the data of more than 1.3 million cancer patients who were diagnosed in California and Georgia between 2013 and 2019 and met national guidelines for genetic testing. The patients included people diagnosed with breast, colorectal, endometrial, ovarian (including fallopian and peritoneal), pancreatic, or lung cancer. People with more than one type of cancer were grouped separately.

Researchers asked whether cancer patients who were eligible for genetic testing according to national guidelines were tested within two years after their diagnosis. Of the more than 1.3 million patients represented in this study, only 6.8 percent of eligible cancer patients had genetic testing.

Rates of genetic testing among different cancer patients

Cancer diagnosed

Rate of genetic testing

Male breast




Female breast


Multiple cancers










  • Rates of testing were different by age:
    • 18% among people age 40
    • 2% among people age 80

Non-Hispanic white patients had higher rates of testing compared to all other racial groups:

  • 6% Asian patients
  • 6% Black patients
  • 6% Hispanic patients
  • 8% non-Hispanic white patients

This testing gap did not improve during this study (2013 to 2019). In the later years of this study, genetic testing rates remained the same among Asian and Black patients but declined among Hispanic patients.

  • The largest differences in genetic testing rates among racial and ethnic groups were among people with breast cancer (men or women) or ovarian cancer.

Results of genetic testing among patients diagnosed with cancer

Among patients who completed genetic testing, 11-36 percent tested positive for a mutation associated with an increased risk of cancer, also known as a pathogenic variant. (The data below reflects 2019 data):

  • female breast: 11%
  • male breast: 36%
  • colorectal: 17%
  • endometrial: 12%
  • ovarian: 15%
  • pancreatic: 14%
  • prostate: 11%
  • lung: 13%
  • multiple primary tumor types: 17%

Treatment or prevention options based on national guidelines were available for most harmful mutations (pathogenic variants)—68-95% depending on the type of cancer.

In addition to harmful mutations, genetic testing also finds Variants of Uncertain Significance or . are uncertain results, meaning that it is unclear whether or not the mutation increases a person’s cancer risk. Some are eventually reclassified as harmful mutations when more data is collected, but many turn out to be harmless or remain as because they are rare.

The chance of having a genetic test that found a was higher among non-white racial groups and has increased with time. Data from 2019 shows that:

  • Among white patients, were found nearly twice as often (25%) as harmful mutations linked to cancer (14%).
  • Among Hispanic patients, were found just over twice as often (29%) as harmful mutations (13%).
  • Among Asian and Black patients, were found about four times (39-40%) as often as harmful mutations (10-11%).

Because are inconclusive results, they cannot be used to guide treatment. These racial disparities in results mean that more people of color receive inconclusive test results. This suggests that more research including people from diverse racial and ethnic groups is needed to close this testing gap and improve these disparities.

What does this mean for me?

National guidelines recommend who should receive genetic testing. These recommendations vary by cancer type and other factors (linked here). In some cases, a single diagnosis of cancer at any age may be enough to recommend genetic testing (for example, male breast cancer, pancreatic or ovarian cancer). For breast cancer, colorectal cancer or certain other cancers, genetic testing may be recommended if you have a family history of cancer, cancer before age 50 or other factors suggesting based on tumor testing (for example, or colorectal or endometrial cancer).

If you have been diagnosed with cancer, talk to a genetics expert about whether you should consider genetic testing. Genetic testing may clarify whether you have a mutation that increases your cancer risk or a variant with uncertain impact. Genetic testing can also provide information that helps other family members understand whether they may have an increased risk of cancer.

If you have an , this knowledge may alter available treatment options. Some medications or treatments are only indicated for people with particular inherited mutations. Having an may increase your risk of other cancers. Consider discussing with your doctor whether increased surveillance or risk-reducing approaches are available. For more information on genetic testing guidelines, visit the FORCE website.


Kurian AW, Abrahamse P, Furgal A, et al. Germline genetic testing after cancer diagnosis. JAMA; 2023; 330:43-51. Published online June 5, 2023.

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.


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posted 3/15/24

Questions To Ask Your Doctor
Questions To Ask Your Doctor

  • Should I have genetic testing?
  • What are the risks and benefits of genetic testing?
  • How do I find a genetic counselor?
  • I have been diagnosed with cancer; how might genetic testing change my treatment plan?
  • How do I talk to my family about genetic testing and my genetic testing results?
  • If I have , should I consider increased surveillance or other options to reduce my risk of other cancers?

Open clinical trials
Open clinical trials

The following clinical trials include genetic counseling and testing. 

Other genetic counseling or testing studies may be found here.


Updated: 02/29/2024

Finding experts
Finding experts

The following resources can help you locate a genetics expert near you or via telehealth.

Finding genetics experts

  • The National Society of Genetic Counselors website has a search tool for finding a genetic counselor by specialty and location or via telehealth. 
  • InformedDNA is a network of board-certified genetic counselors providing this service by telephone. They can also help you find a qualified expert in your area for face-to-face genetic counseling if that is your preference. 
  • Gene-Screen is a third-party genetic counseling group that can help educate, support and order testing for patients and their families. 
  • JScreen is a national program from Emory University that provides low-cost at-home genetic counseling and testing with financial assistance available.
  • Grey Genetics provides access to genetic counselors who offer genetic counseling by telephone. 
  • The Genetic Support Foundation offers genetic counseling with board-certified genetic counselors. 

Related experts

Genetics clinics

Other ways to find experts

Updated: 07/21/2023

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