Cascade Testing: Why Your Results Matter for Your Family

If you have undergone genetic testing and a pathogenic variant was identified, one of the most important things you can do is share that information with your biological relatives. The process of testing family members for a known variant is called cascade testing, and it is one of the most effective strategies in all of preventive medicine.

When a hereditary cancer variant is identified in an individual, each first-degree relative (parent, sibling, or child) has a 50 percent chance of carrying the same variant. Cascade testing is the process of offering targeted genetic testing for the specific family variant to these at-risk relatives. Unlike the initial broad panel test, cascade testing is focused on a single known variant, making it faster, less expensive, and more definitive. The most common genes that trigger cascade testing include BRCA1, BRCA2, the Lynch syndrome genes MLH1 and MSH2, and moderate-risk genes such as CHEK2 and PALB2.

For relatives who test positive: they can begin enhanced screening appropriate to their specific gene and cancer risks. Cancers detected through enhanced screening are found at earlier stages, when treatment is less aggressive and outcomes are significantly better.

For relatives who test negative: a negative cascade test in the context of a known family variant is a “true negative.” Their cancer risk for that syndrome returns to approximately that of the general population. For more on the distinction between true negative and uninformative negative results, see our guide to understanding genetic test results.

A single positive genetic test result can extend across an entire family tree. Within two generations, a single initial finding can lead to the identification of multiple carriers — each of whom can benefit from personalized screening and prevention. For an overview of who should consider testing, see our hereditary cancer screening guide.

Telling family members about a hereditary variant is not always easy. Lead with care, be clear about what it means, respect autonomy, and expect a range of reactions. A genetic counselor can help you prepare for these conversations. Learn more in our guide for recently diagnosed patients or for family members of someone diagnosed.

Despite its proven value, cascade testing rates remain low — fewer than 30 percent of at-risk relatives are tested. Common barriers include lack of awareness, family communication challenges, cost concerns (cascade testing is typically less expensive and often covered by insurance), and fear. Our BRCA testing guide covers what the testing process involves and how to prepare. Read about overcoming the fear of testing.

By initiating cascade testing today, you are not just protecting your siblings and cousins. You are potentially protecting nieces, nephews, and future generations. The NCCN recommends that genetic testing for hereditary cancer variants generally be considered beginning at age 18 to 25. Learn about insurance coverage for genetic testing.

LifeShield offers tools to help families navigate cascade testing with minimal friction. If you receive a positive result through LifeShield, your genetic counselor can help you share information with at-risk relatives in two ways:

• Named outreach: With your permission, LifeShield can send a personalized letter or message to specific family members, including your name and the relevant variant information. This approach is direct and often the most effective way to encourage relatives to pursue testing.
• Anonymous outreach: If you prefer not to be identified, LifeShield can send a general notification to family members informing them that a hereditary cancer variant has been identified in their family, without disclosing your identity. This option respects your privacy while still alerting relatives to a potentially actionable finding.

In both cases, the communication includes clear information about what cascade testing involves, why it matters, and how relatives can access testing. The goal is to lower the barriers that prevent families from acting on potentially life-saving information.