Simplified and more sensitive criteria for identifying individuals with pathogenic CDH1 variants

Hereditary diffuse gastric cancer (HDGC) is an autosomal-dominant syndrome most often caused by pathogenic variants in CDH1. The International Gastric Cancer Linkage Consortium (IGCLC) recently updated its criteria for genetic testing. The purpose of this study was to estimate the sensitivity of IGCLC's 2020 criteria for identifying carriers of CDH1 pathogenic variants and to formulate a new set of criteria that is simpler and more sensitive.

Medical histories of 112 CDH1 mutation carriers, identified predominantly by multigene panel testing, and their 649 family members were reviewed. The percentage of subjects fulfilling the IGCLC 2015 and 2020 criteria was calculated, once without making any assumptions about unavailable pathology, and once assuming gastric cancer to be diffuse when pathology was unavailable. For comparison, we calculated the percentage of subjects who fulfilled our proposed criteria.

When making no assumptions about missing pathology, a small (19%) and equal percentage of CDH1 mutation carriers fulfilled the IGCLC 2015 and 2020 criteria. When assuming unspecified gastric cancer to be diffuse, 45 out of 112 (40%) subjects met the 2015 criteria and 53 out of 112 (47%) met the 2020 criteria. Eighty-seven per cent (97/112) fulfilled our proposed criteria.

In consecutive cases, mostly unselected for clinical criteria of HDGC, the IGCLC 2020 criteria are, at best, marginally more sensitive than previous iterations, but they are also more cumbersome. Unavailable cancer pathology reports are a real-world obstacle to their proper application. Our proposed Yale criteria both address this issue and offer significantly greater sensitivity than the IGCLC 2020 criteria.