CDH1 and breast cancer: It has been postulated that loss of E‐cad expression is an early gatekeeper event in in situ lobular breast cancer and a precursor of invasive lobular breast cancer.7, 11 Over the last several years, a number of mechanisms have been identified as the cause of E‐cad inactivation in breast cancer.12, 13, 14 Inactivating mutations in the CDH1 gene have been frequently described and can explain a great proportion of invasive lobular breast cancer cases.