I Was Just Diagnosed with Cancer. Should My Family Get Tested?

A cancer diagnosis changes everything — your relationship with your body, your daily priorities, your sense of the future. In the middle of processing that, you may find yourself asking a question that many newly diagnosed patients describe as the hardest one: could I have passed this to my children?

If that question is on your mind, you are not alone. And the answer, in many cases, can be found through genetic testing.

Why Genetic Testing Matters After a Cancer Diagnosis

Genetic testing is equally valuable, and in many cases even more clinically important, for people who have already received a cancer diagnosis. If your cancer was caused by an inherited gene variant, that information can affect your treatment options, may influence surgical decisions, and has direct implications for your blood relatives.

Guidelines from the NCCN now recommend germline genetic testing for all patients diagnosed with breast cancer at age 65 or younger, all ovarian cancer at any age, all pancreatic cancer, colorectal cancer before age 50, metastatic prostate cancer, and several other cancer types.

What Testing Can Reveal for You

• Treatment selection. Certain targeted therapies, including PARP inhibitors, are specifically effective in cancers associated with BRCA1, BRCA2, and other DNA repair gene variants.
• Surgical planning. The discovery of a hereditary variant may inform decisions about the extent of surgery.
• Surveillance for second cancers. Hereditary cancer variants often increase risk for more than one type of cancer. Knowing your variant status enables appropriate surveillance.

What It Means for Your Family

If you carry a pathogenic variant in a gene like BRCA1, BRCA2, or one of the Lynch syndrome mismatch repair genes, each of your first-degree relatives — children, siblings, and parents — has a 50 percent chance of carrying the same variant. Learn more about cascade testing for families.

• Targeted testing. Once a specific variant has been identified, testing for that exact variant in relatives is faster, less expensive, and more definitive.
• Earlier screening. Relatives who test positive can begin enhanced screening years or decades before cancer would typically be detected.
• Prevention options. For some high-risk gene variants, evidence-based preventive interventions exist that can significantly reduce cancer risk.
• Peace of mind. Relatives who test negative can be reassured that their risk is likely similar to the general population for that syndrome.

How to Talk to Your Family

You are under no obligation to share your genetic information with anyone. But many patients find that informing close relatives is one of the most meaningful things they can do. You might say: “I had genetic testing as part of my cancer care, and it found a hereditary gene change that may be relevant to our family.”

Remove pressure, offer a resource rather than an assignment, and expect a range of reactions. Some relatives will want to act immediately; others may need time. See our guide for family members of someone just diagnosed.

If You Were Diagnosed Years Ago

If your cancer diagnosis was not recent but you were never offered genetic testing, it is still worthwhile. Testing guidelines have expanded significantly over the past decade. There is no expiration date on the value of understanding your hereditary cancer risk. Read more in our article about genetic testing for cancer survivors.

Taking the Step

If you are in active treatment, your oncology team can often order genetic testing as part of your care. If you are past treatment or prefer to pursue testing independently, a clinical risk assessment can help determine the most appropriate next step. Learn about the genetic testing process.