Genetic testing and family cancer risk

When cancer may run in the family, what testing can show, and what results mean for your relatives.

Rosa: Hi, I'm Rosa. Sometimes cancer runs in families. Let me explain what genetic testing can show, and what the results might mean for you and your relatives.

Most cancers are not inherited. They come from gene changes that happen during life. But some people are born with a gene change that raises their cancer risk. This is called a hereditary or inherited cancer risk. It can be passed from parent to child.

There are two kinds of gene testing in cancer care. Tumor testing (also called biomarker testing) looks at the cancer itself to help choose treatment. Germline testing looks at the genes you were born with, usually using blood or saliva. This page is about germline testing. Sometimes tumor testing finds a change that suggests you should also have germline testing.

Testing is now recommended for everyone with some cancers, such as ovarian, pancreatic, and prostate cancer that has spread. It is also recommended for many people with breast or colon cancer, especially at a younger age. Other signs include cancer at a young age or more than one cancer. Several relatives with related cancers, or Ashkenazi Jewish ancestry, are also signs.

Results can help you. They may open the door to certain treatments. Examples are PARP inhibitors for some BRCA gene changes, and immunotherapy for many cancers linked to Lynch syndrome. They can guide surgery choices, earlier or more frequent screening, and ways to lower risk of a new cancer.

Results can also help your family. If you have an inherited gene change, your parents, brothers, sisters, and children each may have it too. They can get tested for that exact change. If they have it, they can start screening early. If they do not, they may not need extra screening.

A genetic counselor can help before and after testing. They review your family history and explain what the test can and cannot show. They also help you share results with relatives. Many counselors meet by phone or video.

Positive result

A harmful gene change was found. Your team will talk about what it means for your treatment, screening, and ways to lower risk. Relatives can be tested for the same change.

Negative result

No harmful change was found in the genes tested. This is good news, but it does not mean zero risk. Your family history still matters for screening. If you were tested many years ago, ask if newer testing makes sense.

Variant of uncertain significance (VUS)

A change was found, but experts do not yet know if it raises risk. Most turn out to be harmless. Treatment and screening are not changed because of a VUS. Relatives should not be tested for it. Results may be updated later.

Common inherited conditions

The most common are BRCA1 and BRCA2 (breast, ovarian, prostate, and pancreatic cancer). Another is Lynch syndrome (colon, uterine, and other cancers). There are many others.

Insurance and privacy

A US law called GINA protects you from genetic discrimination by health insurers and most employers. It does not cover life, disability, or long-term care insurance. Some people think about this before testing.

Cost

Testing is often covered by insurance when guidelines say you qualify. Many labs offer low-cost options. Relatives can often get testing for a known family change at low cost.

Myth: if no one in my family had cancer, I cannot have an inherited gene change

Fact: many people with inherited gene changes have no strong family history. That is why testing is now offered more widely.

Questions to ask

Should I have germline testing? Can I meet with a genetic counselor? How will results change my treatment? Who in my family should be tested?

• Write down cancers in your family on both sides: who, what type, and age at diagnosis.
• Ask your care team if germline testing is recommended for you.
• Ask for a genetic counseling visit.
• Keep a copy of your genetic test report.
• If a harmful change is found, share the results with blood relatives.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.