CDH1 Germline Mutations in Lobular Breast Cancer

Invasive lobular breast carcinoma (ILBC) represents 5-15% of all invasive BCs. The CDH1 gene (OMIM no. 192090), located on the chromosome 16q22.1, encodes for the E-cadherin protein, a key regulator of cell adhesion. Loss of E-cadherin expression is frequently detected in LBC CDH1 germline loss-of-function mutations are associated with the autosomal dominant cancer-predisposition syndrome, hereditary diffuse gastric cancer (HDGC; OMIM no. 137215). The cumulative risk of LBC for women with a CDH1 mutation is estimated to be 42% (95% CI 23% to 68%) by 80 years, when it is a component of HDGC syndrome. Recently, some authors described CDH1 germline mutations in women with in situ or ILBC with early onset (\<45 or \<50) and bilateral in situ or ILBC with no family history of HDGC. These results are opening a new scenario, suggesting that CDH1 could be a susceptibility gene for LBC in women without a family history of DGC. The first aim of this study is to investigate prevalence of CDH1 in this specific population of women with early onset (\<45 or \<50) in situ or ILBC, bilateral LBC or LBC with no family history of HDGC.