How would you approach breast cancer screening in an adolescent patient with a CDH1 mutation?

The timing of initiation of breast cancer screening in an adolescent female with a germline CDH1 pathogenic variant will depend on family history. Initially, I follow the NCCN guidelines which recommend starting screening mammograms +/- breast MRIs annually at age 30. If there is a family history of early-age breast cancer diagnosis for the patient, I'd consider starting screening ~5 years before the age when the relative was diagnosed, if that's below 30. I'd note that in adolescents, breast MRIs are typically easier to interpret compared to mammograms, depending on breast size and density. There aren't any specific screening recommendations in the adolescent years unless there's a family member diagnosed with breast cancer at a particular...