Survey of cancer genetics: Genetic testing implications

The identification of an increasing variety of 'cancer genes,' thereby signifying the cancer destiny of patients from hereditary cancer families, offer numerous opportunities for cancer surveillance and management, including prophylactic surgery in selected circumstances. This new science and technology has emerged at a rapid pace, making it difficult for many physicians to grasp its full impact. This article reviews the genetics and molecular genetics of cancer and updates its genetic counseling implications. Several hereditary cancer syndromes are reviewed as cancer genetic models, including multiple endocrine neoplasia types 2A and 2B, neurofibromatosis, familial pancreatic carcinoma, familial atypical multiple mole melanoma syndrome, and von Hippel-Lindau disease. Special attention is given to the distinctive pathology features that may appear in certain hereditary cancer syndromes, with hereditary nonpolyposis colorectal carcinoma discussed as a prototypic model. Genetic testing issues including variable positions relevant to whether and/or when to test and whom to test, as well as the position of the American Society of Clinical Oncology, are also discussed.