title: [Study on family aggregation of esophageal cancer in Linzhou city].
abstract: OBJECTIVE
  To investigate family aggregation of esophageal cancer (EC) in Linzhou city, a high risk area for EC.
  
  
  METHODS
  A hospital based case-control study were conducted, which included relatives of 118 EC cases and 168 controls. EC incidences in relatives of cases and controls were compared by chi 2 test and risk ratio (RR) was calculated. Heritability (h2) was estimated using the Falconer method.
  
  
  RESULTS
  EC incidence of case relatives was significantly higher than that in control relatives. The RR was 3.15 (2.15-4.61) in the first degree relatives and 1.87 (1.26-2.79) in the second degree relatives. The heritability was (53.39 +/- 5.93)% for the first degree relatives and (50.21 +/- 10.75)% for the second degree relatives, while the weighted h2 was (52.26 +/- 3.82)%.
  
  
  CONCLUSIONS
  The genetic factor plays an important role the occurrence of EC in Linzhou city; however, environmental factors should not be ignored.
authors.affiliation: Department of Epidemiology, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Shi
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: C
authors.initials: C
authors.lastname: Sun
mesh_terms: D000328:Adult; D000368:Aged; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D004938:Esophageal Neoplasms / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged