title: Congenital abnormalities and childhood cancer.
abstract: BACKGROUND
  The examination of specific characteristics of neoplasms diagnosed in children have suggested that a significant proportion can be attributed to a genetic mutation or genetic predisposition. Although the study of a genetic predisposition to cancer in children remains in the early stages, congenital abnormalities could provide essential information for mapping predisposing lesions in children with cancer.
  
  
  METHODS
  In the current study, 2 large cohorts of children with and without congenital abnormalities were followed for the occurrence of cancer and death up to 18 years. Through this study, the risk of developing cancer by age at diagnosis, effects of birth characteristics on cancer risk, and possible associations between specific anomalies and tumor types were examined.
  
  
  RESULTS
  Based on the follow-up of 90,400 children, the risk of developing cancer during the first year of life was found to be nearly 6 times higher in children with anomalies (rate ratio [RR] of 5.8; 95% confidence interval [95% CI], 3.7-9.1). Children with birth defects were found to be at a higher risk for developing leukemia (RR of 2.7; 95% CI, 2.1-3.6), tumors of the central nervous system (RR of 2.5; 95% CI, 1.8-3.4), sympathetic nervous system tumors (RR of 2.2; 95% CI, 1.4-3.4), and soft tissue sarcomas (RR of 1.9; 95% CI, 1.0-3.5). Among children with birth defects, children with Down syndrome, nervous system anomalies, and anomalies of the urinary system had the highest incidence rates of cancer. In the presence of birth defects, other factors such as birth weight, gestational age, age of the mother, and birth order were not found to be associated significantly with the risk of cancer.
  
  
  CONCLUSIONS
  The significant relative risks found in the current study provided evidence of links between the presence of abnormalities and the development of cancer. Some "cancer-prone" abnormalities were identified in the current study. Such anomalies may be markers of other exposures or processes that increase the risk of developing cancer.
authors.affiliation: Pediatric Oncology Group of Ontario, Toronto, Ontario, Canada. mohammad@ices.on.ca
authors.forename: Mohammad M
authors.initials: MM
authors.lastname: Agha
authors.forename: Jack I
authors.initials: JI
authors.lastname: Williams
authors.forename: Loraine
authors.initials: L
authors.lastname: Marrett
authors.forename: Teresa
authors.initials: T
authors.lastname: To
authors.forename: Alvin
authors.initials: A
authors.lastname: Zipursky
authors.forename: Linda
authors.initials: L
authors.lastname: Dodds
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D016543:Central Nervous System Neoplasms / Q000209:etiology*; D002648:Child; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000473:pathology*; D004314:Down Syndrome / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007938:Leukemia / Q000209:etiology*; D008297:Male; D008423:Maternal Age; D008498:Medical Record Linkage; D012307:Risk Factors; D012509:Sarcoma / Q000209:etiology*