Screening for cancer in high risk families

To review screening for cancer in high risk families.

Screening for hereditary cancer involves three steps: it is first necessary to identify families at high risk by examining the number and sites of cancer in a family. Special attention is given to cancers appearing at an early age, to unusual sites, and multiple primary cancers. Second, a molecular diagnostic test is performed in order to identify family members who carry a mutant copy of the suspected gene. DNA-based diagnostic testing is now available for hereditary breast-ovarian cancer, for hereditary nonpolyposis colon cancer, for Gardner syndrome (familial polyposis coli), for neurofibromatosis, multiple endocrine neoplasia, and for Von-Hippel Lindau disease. Third, individuals found to carry susceptibility genes are offered screening for the early detection of tumours. Some screening methods are in conventional use (e.g., colonoscopy and mammography); others are reserved for the investigation of familial cancers (e.g., pentagastrin challenge test).

A comprehensive clinic for hereditary cancer must consider all three phases of the screening program and will provide expert genetic counselling to family members involved in the process.