Screening for cancer in high-risk families.

Abstract

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.