Hereditary breast cancer and family cancer syndromes.

Hereditary breast cancer (HBC) shows extant clinical and genetic heterogeneity. Clinically one finds the onset of breast cancer at an early age, an excess of bilaterality, and patterns of multiple primary cancer such as combinations of breast and ovarian carcinoma in the hereditary breast-ovarian cancer (HBOC) syndrome. In addition to HBOC, one sees a variety of putative breast cancer-prone genotypes inclusive of hereditary site-specific breast cancer, and the Li-Fraumeni (SBLA) syndrome that is characterized by cancers involving all three germinal layers including sarcomas, brain tumors, leukemia, lymphoma, and adrenal cortical carcinoma in addition to often markedly early-onset breast cancer. Breast cancer is also associated with autosomal dominantly inherited Cowden's disease and autosomal recessively inherited ataxia-telangiectasia. Examples of pedigrees depicting clinical examples of these several HBC syndromes are presented in order to describe HBC's heterogeneity. The recent identification of the BRCA1 gene in early-onset hereditary site-specific breast cancer and the HBOC syndrome has led to new challenges for the genetic counselor. We review genetic counseling, which embraces surveillance and management recommendations that are responsive to the natural history of HBC and address the concept for future development of centers of expertise for HBC in the interest of improving cancer control.