title: A comprehensive survey of cancer risks in extended families.
abstract: OBJECTIVE
  Cancer is familial; yet known cancer predisposition genes, as well as recognized environmental factors, explain only a small percentage of familial cancer clusters. This population-based description of cancer clustering describes patterns of cancer coaggregation suggestive of a genetic predisposition.
  
  
  METHODS
  Using a computerized genealogy of Utah families linked to a statewide cancer registry, we estimated the relative risks for 36 different cancer sites in first-, second-, and third-degree relatives of cancer cases, for each cancer site individually, and between cancer sites. We estimated the sex- and birth-year-specific rates for cancer using 1 million individuals in the resource. We applied these rates to groups of cases or relatives and compared the observed and expected numbers of cancers to estimate relative risks.
  
  
  RESULTS
  Many cancer sites show significantly elevated relative risks among distant relatives for cancer of the same site, strongly supporting a heritable contribution. Multiple combinations of cancer sites were observed among first-, second-, and third-degree relatives, suggesting the existence of heritable syndromes involving more than one cancer site.
  
  
  CONCLUSIONS
  This complete description of coaggregation of cancer by site in a well-defined population provides a set of observations supporting heritable cancer predispositions and may support the existence of genetic factors for many different cancers.
authors.affiliation: Division of Genetic Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA. craig.teerlink@utah.edu
authors.forename: Craig C
authors.initials: CC
authors.lastname: Teerlink
authors.forename: Frederick S
authors.initials: FS
authors.lastname: Albright
authors.forename: Lauro
authors.initials: L
authors.lastname: Lins
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Cannon-Albright
mesh_terms: D005190:Family; D005789:Genealogy and Heraldry; D020022:Genetic Predisposition to Disease; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology* / Q000235:genetics; D012042:Registries; D012306:Risk; D014589:Utah / Q000453:epidemiology