Genetic factors and their role in detection of cancer

Familial aggregations of cancer have long suggested that genetic factors might be important in a small fraction of cancers. However, recent evidence suggests that probably all cancers develop in at least two distinct populations, one of which is genetically predisposed to that cancer through an autosomal dominantly inherited gene. Characteristics of such hereditary cancers include an earlier average age at diagnosis, frequent multiplicity of cancer of the same or associated organs, occasional association with stigmatizing anomalies or detectable premalignant lesions, and a positive family history of cancer of the same or related site. Identification of individuals at risk for cancer due to a hereditary predisposition may lead to early cancer detection or prevention. Gene carriers for genes that carry a high risk cancer may be identified prior to cancer development by the following characteristics: Presence of hereditary cancer syndromes including stigmatizing anomalies or detectable premalignant lesions. Identification of potential gene carriers through pedigree studies of individuals with genetically determined malignancies. Follow-up of patients with a genetically determined malignancy who may be at risk for developing a subsequent malignancy of the same or other organ site. Screening examinations or surgical intervention in such high-risk individuals may lead to early cancer detection or prevention. Further, study of these high-risk individuals may lead to development of more effective methods of cancer screening and detection applicable to the general population.