This trial will recruit young adult female relatives (YARs) of male or female carriers of BRCA1/2. YARs who consent to participate will be randomized to either a 3-session peer coach-led telephone counseling intervention or usual care navigation to peer support interventions provided by community organizations that support the hereditary cancer community. Study aims are to 1) Assess intervention effects on distress and decision making outcomes, including uptake of counseling for untested YARs, 2) Identify YARs most likely to engage with and benefit from the intervention, 3) Understand intervention mechanisms. Participants will complete interviews at baseline, 1, 6, and 12 months.

Germline (e.g., BRCA) mutation carriers have highly elevated odds of developing hereditary breast-ovarian cancer (HBOC), as could their relatives. Referral to genetic counseling is the standard of care for young, at-risk adult relatives (i.e., ages 18-39; herein "YARs"). However, many female YARs struggle to make decisions about familial HBOC risk management, including whether and when to pursue genetic counseling, how to cope with stress and uncertainty about HBOC, and how to navigate lifecycle events entwined with HBOC threats (e.g., childbearing). Prior work points to YARs' strong desires to seek HBOC risk information and emotional support beyond traditional genetic counseling-especially support from knowledgeable peers who can relate to their experiences and offer neutral grounding and objective guidance about coping strategies. Peer support is a promising psychosocial cancer care approach that could fill this void. However, few evidence-based standards inform its practice as an adjunct to cancer genetic counseling. As genetic testing for HBOC risk expands population-wide, new ways must be tested to reach, educate, and support YARs to further reduce the cancer burden in communities of at-risk women. The 2-arm PeACE trial includes streamlined telephone counseling delivered by well-trained community peer coaches, with session content incorporating coping training for HBOC stress reduction, and decision making and problem solving training about genetic counseling and HBOC risk. Trial participants are female YARs (aged 21-30) randomized to an intervention or equated control condition, and followed for up to 12 months.

Inclusion Criteria:

• There are two targets for recruitment with different eligibility criteria.

Index carriers:

• Men or women aged 18 or older with BRCA mutations with or without 2nd-tier multiplex panel genetic testing. Index carriers will have received testing.

YARs:

• Female 1st-, 2nd- or 3rd-degree biological relatives of index carriers aged 21-30.

Exclusion Criteria:

• Must be able to speak English or Spanish and provide informed consent

Index carriers can be men and women; those taking part in peer coaching will be female.