title: Risk for cancer in parents of patients with schizophrenia.
abstract: OBJECTIVE
  This study attempted to determine whether a genetic protection against cancer might be manifest in parents of offspring with schizophrenia.
  
  
  METHODS
  Using data from the Danish Central Population Registry, the authors identified 1,999,072 parents of offspring born after 1935. By linking this nationwide population-based parent cohort to the Danish Psychiatric Central Register, they identified 19,856 parents of offspring with schizophrenia. Follow-up for cancer in the Danish Cancer Registry began on the date of birth of the oldest child or April 1, 1969, and ended on the date of cancer diagnosis, death, or Dec. 31, 1997, yielding a total of 48,343,430 person-years at risk and 211,681 cases of cancer. The relative risk for cancer among parents with schizophrenic offspring compared to parents with no schizophrenic offspring was estimated by Poisson regression analysis and adjusted for age, period, and number of children.
  
  
  RESULTS
  The risk for all cancer was 1.01 for fathers and 1.00 for mothers of schizophrenics. Mothers of schizophrenic patients had an increased risk of 1.20 for lung cancer and a nonsignificant risk of 1.14 for tobacco-related cancers combined. Apart from a reduced risk for leukemia in both mothers and fathers of schizophrenics, there was no difference in risk for any other cancer.
  
  
  CONCLUSIONS
  This study does not confirm a previously reported reduced risk for cancer in parents of schizophrenic patients and provides no support for genetic protection against cancer in families with schizophrenia.
authors.affiliation: Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark. sanne@cancer.dk
authors.forename: Susanne Oksbjerg
authors.initials: SO
authors.lastname: Dalton
authors.forename: Thomas Munk
authors.initials: TM
authors.lastname: Laursen
authors.forename: Lene
authors.initials: L
authors.lastname: Mellemkjaer
authors.forename: Christoffer
authors.initials: C
authors.lastname: Johansen
authors.forename: Preben Bo
authors.initials: PB
authors.lastname: Mortensen
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005192:Family Health; D005220:Fathers; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007938:Leukemia / Q000453:epidemiology / Q000235:genetics / Q000517:prevention & control; D008175:Lung Neoplasms / Q000453:epidemiology / Q000235:genetics; D008297:Male; D009035:Mothers; D009369:Neoplasms / Q000453:epidemiology* / Q000235:genetics / Q000517:prevention & control; D010290:Parents; D012306:Risk; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology* / Q000235:genetics