What are the implications of a positive genetic test result for my patient's family members regarding their cancer risk?

A positive genetic test result indicating a pathogenic variant associated with cancer (such as BRCA1, BRCA2, or mismatch repair genes) implies that the patient's family members may have an increased risk of developing related cancers, including breast and ovarian cancer.

Family members, especially first-degree relatives (parents, siblings, children), have a higher probability of carrying the same pathogenic variant and therefore an elevated cancer risk.

This necessitates offering genetic counselling and potentially predictive genetic testing to at-risk relatives to assess their carrier status and guide appropriate surveillance or risk-reducing interventions.

Genetic counselling should include discussion of the implications of a positive result, the likelihood of inheritance, and the options for risk management, including surveillance and preventive surgery.

Furthermore, cascade testing is recommended to identify other family members who may carry the pathogenic variant, enabling early detection and management of cancer risk.