Management Considerations in a Patient With a Germline CDH1 Pathogenic Variant and a History of Roux-en-Y Gastric Bypass Surgery

Individuals with a germline pathogenic variant in the CDH1 gene have a lifetime risk of advanced diffuse gastric cancer (DGC) of up to 10.3% and a 37%-52% risk of breast cancer, specifically the lobular subtype. Guidelines recommend prophylactic gastrectomy between ages 18-40 years for those with a family history of DGC. For patients declining surgery or lacking a family history of DGC, annual endoscopic surveillance according to recommended protocols is an alternative. This case reviews the management of a patient with a history of Roux-en-Y gastric bypass followed one year later by a diagnosis of lobular breast cancer due to a germline CDH1 pathogenic variant.