CDH1 germline mutations in families with hereditary lobular breast cancer

Pathogenic CDH1 germline mutations are associated with lobular breast cancer in the so-called hereditary lobular breast cancer (HLBC) syndrome, without apparent correlation with the classic hereditary diffuse gastric cancer (HDGC). Recent international guidelines recommend CDH1 screening also in absence of diffuse gastric cancer (DGC) history. Genomic characteristics underlying gastric and breast tumorigenesis in this varied population of patients is still unclear. In this review we revised all CDH1 germline mutations described in literature associated with lobular breast cancer (LBC). We distinguish two subgroups of CDH1 mutant carriers: (a) 'mixed' HDGC syndrome, showing both DGC plus LBC and (b) HLBC, in which DGC is absent and the LBC phenotype is predominant. A higher frequency of CDH1 mutations was identified in the HLBC syndrome with an early age at LBC diagnosis; it is possible that LBCs with CDH1 germline mutations are an independent inherited syndrome. This evidence allows us to gain biological insight into the pathophysiological mechanisms responsible for the different phenotypes of the disease and potentially tailor the prophylactic and screening procedures.