ABSTRACT
The identification of patients with a genetic predisposition to cancer is emerging as an important component of medical practice. Essential clues to the presence of an inherited cancer predisposition lie in characteristics of the family history, including the proportion of family members affected with cancer, the type of cancer, and the age of onset in those affected. Genetic cancer traits are distinguished by the dramatic clustering of cancers within an affected family. The greater the number of affected relatives and the more closely related they are, the greater the likelihood that an individual may carry an inherited predisposition to cancer. Familial clustering of cancers such as those of breast, ovary, and colon have been recognized as following Mendelian patterns of inheritance in some families. With molecular genetic analysis, the responsible genes for many of these cancer syndromes have been identified.
