Familiality of cancer in Utah.

The Utah Population Database allows examination of the genetic relationships among the 35.7% of all cancer cases in the state that have genealogical records. Familial clustering of cancer is measured by the Genealogical Index of Familiality and is examined by site, and within site by age of onset, histology, and gender. Most cancer sites examined show excess familiality for all cases considered together. Subsets of individuals with certain characteristics showed unusually high levels of familial clustering, specifically lymphocytic leukemias and especially chronic lymphocytic leukemia, lobular breast cancer, early lip cancer, early melanoma, and female lung cancers of alveolar/adenoma histology. These may represent characteristics of the most penetrant forms of inherited susceptibilities, those which are enhanced by environmental factors, chance aggregations, rare inherited syndromes, or a combination of these factors.