Background: Hereditary diffuse gastric cancer (HDGC) represents a minority of gastric cancer (GC) cases. The goal of this study is to use a RAND/University of California Los Angeles (UCLA) appropriateness methodology to examine indications for genetic referral, CDH1 testing, and consideration of prophylactic total gastrectomy (PTG). Methods: A multidisciplinary expert panel of 16 physicians from six countries scored 47 scenarios. Appropriateness of scenarios was scored from 1 (highly inappropriate) to 9 (highly appropriate). Median appropriateness scores (AS) of 1-3 were considered inappropriate, 4-6 uncertain, and 7-9 appropriate. Agreement was reached when 12 of 16 panelists scored the statement similarly. Appropriate scenarios agreed upon were subsequently scored for necessity. Results: The panel felt that patients with family history of diffuse gastric cancer (DGC), lobular breast cancer, or multiple family members with GC should be referred for genetic assessment and multidisciplinary decision-making. The panel felt that it is appropriate for patients with DGC to have CDH1 mutation testing in a family with (1) ≥2 cases of GC, with at least one case of DGC diagnosed before age of 50 years; (2) ≥3 cases of GC diagnosed at any age, one or more of which is DGC; (3) a patient diagnosed with DGC and lobular breast carcinoma; or (4) patients diagnosed with DGC under age of 35 years. The panel felt that PTG should be offered to CDH1 mutation carriers 20 years or older. Conclusions: Identification of genetic mutations in patients at risk for hereditary GC is important, and criteria for testing are suggested.
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