Inherited Cancer Risk: Family History and Genetic Testing

Updated 23 October 2026 · Cancer Point

Cancer involves changes in genes, but that does not mean every cancer is inherited. Understanding this distinction can help a family ask better questions without assuming that a diagnosis determines everyone's future.

Inherited and acquired changes are different

An inherited, or germline, change is passed through a family. Other changes develop in cells during a person's lifetime. Testing a tumour to help choose treatment is a different task from testing for inherited risk. A tumour result may suggest a need for further assessment; it does not automatically establish a hereditary condition.

The NCI explains that a family pattern can also reflect shared exposures or chance. Having an inherited risk variant increases the possibility of certain cancers; it does not mean cancer is inevitable.

When to ask about genetic counselling

Bring up a known harmful variant in the family, cancer at an unusually young age, several relatives with related cancers or more than one cancer in the same person. These are reasons for professional assessment, not a diagnosis of a cancer syndrome. Your own cancer type may also be a reason to discuss testing even without a strong family history.

Prepare a family-history sheet

Include relatives on both sides of the family. For each person, record their relationship to you, the cancer type if known and approximate age at diagnosis. Mark uncertain details honestly. “Abdominal cancer, exact type unknown” is more useful than a confident but incorrect guess.

• Ask relatives for permission before collecting or sharing their reports.
• Keep the original wording when you have a pathology result.
• Note who supplied the information and when it was last checked.
• Bring the sheet to the consultation rather than sending it to an unverified testing seller.

If a relative does not want to discuss their health, respect that decision. A genetics professional can work with incomplete information and explain the limits it creates. Do not delay your own medical assessment while trying to build a perfect family tree.

Results need interpretation

A positive result may support a tailored prevention or screening plan. A negative result does not eliminate all cancer risk and can be uninformative when no familial variant is known. A variant of uncertain significance is an unresolved finding, not proof of increased risk; it generally should not guide major medical decisions by itself.

Arrange a results appointment before the test is sent. Ask who will explain the result, whether relatives need a separate discussion and how the clinic communicates a later reclassification. Keep a copy of the actual report, not only a phone screenshot of a summary.

Questions before buying a test

Ask why these particular genes are being tested, what the result could change and whether an affected relative should be assessed first. Clarify the full price, counselling arrangements, laboratory quality and how the sample and data will be stored. These are useful questions for any provider; this site does not recommend a commercial testing kit.

For treatment-related testing, read what a cancer biomarker result can tell you. The next step after a family-history discussion should be an individualized plan with a qualified professional, not a prediction made from a list of surnames or a single online risk score.

This guide provides general education, not a diagnosis or a personal treatment plan. Discuss medical decisions with a qualified healthcare professional. It has not received an independent clinical review. Read our editorial policy and medical disclaimer.