Hereditary diffuse gastric cancer and lobular breast carcinoma

Somatic CDH1 mutations are found in sporadic diffuse type gastric and lobular breast carcinomas. Germline mutations of the CDH1 gene are the molecular genetic cause of hereditary diffuse gastric cancer. CDH1 in this context acts as a classical tumor suppressor gene and lobular breast carcinomas are observed in association with CDH1 germline mutations in hereditary diffuse gastric cancer families. Although some families with a preponderance or even single occurrence of breast carcinomas and a CDH1 germline mutation have been described, the incidence of CDH1 germline mutations in breast cancer families without the presentation of diffuse type gastric cancer is low. This chapter summarizes the current knowledge about CDH1 germline mutations and the occurrence of breast carcinomas in hereditary diffuse gastric cancer families with an emphasis on pathology, type of CDH1 mutations as well as on the clinical management and patient's surveillance regarding breast carcinomas of individuals carrying a CDH1 germline mutation.