title: A systematic review and meta-analysis of perinatal variables in relation to the risk of testicular cancer--experiences of the son.
abstract: BACKGROUND
  We undertook a systematic review and meta-analysis of perinatal variables in relation to testicular cancer risk, with a specific focus upon characteristics of the son.
  
  
  METHODS
  Literature databases Scopus, EMBASE, PubMed and Web of Science were searched using highly sensitive search strategies. Of 5865 references retrieved, 67 articles met the inclusion criteria, each of which was included in at least one perinatal analysis.
  
  
  RESULTS
  Random effects meta-analysis produced the following results for association with testicular cancer risk: birth weight [per kilogram, odds ratio (OR) = 0.94, 95% confidence interval (CI) 0.88-1.01, I(2)= 12%], low birth weight (OR = 1.34, 95% CI 1.08-1.67, I(2)= 51%), high birth weight (OR = 1.05, 95% CI 0.96-1.14, I(2)= 0%), gestational age (per week, OR = 0.95, 95% CI 0.92-0.98, I(2)= 38%; low vs not, OR = 1.31, 95% CI 1.07-1.59, I(2)= 49%), cryptorchidism (OR = 4.30, 95% CI 3.62-5.11, I(2)= 44%), inguinal hernia (OR = 1.63, 95% CI 1.37-1.94, I(2)= 38%) and twinning (OR = 1.22, 95% CI 1.03-1.44, I(2)= 22%). Meta-analyses of the variables birth length, breastfeeding and neonatal jaundice did not provide evidence for an association with testicular cancer risk. When low birth weight was stratified by data ascertainment (record/registry vs self-report), only the category of self-report was indicative of an association. Meta-regression of data ascertainment (record/registry vs self-report) inferred that record-/registry-based studies were less supportive of an association with gestational age (per week = 0.97, 95% CI 0.94-1.00, I(2)( )= 29%; low vs not = 1.08, 95% CI 0.91-1.28, I(2)= 32%).
  
  
  CONCLUSIONS
  In conclusion, this systematic review and meta-analysis finds evidence that cryptorchidism, inguinal hernia and twinning, and tentative evidence that birth weight and gestational age, are associated with risk of testicular cancer.
authors.affiliation: Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20852-7234, USA. cookmich@mail.nih.gov
authors.forename: Michael B
authors.initials: MB
authors.lastname: Cook
authors.forename: Olof
authors.initials: O
authors.lastname: Akre
authors.forename: David
authors.initials: D
authors.lastname: Forman
authors.forename: M Patricia
authors.initials: MP
authors.lastname: Madigan
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Richiardi
authors.forename: Katherine A
authors.initials: KA
authors.lastname: McGlynn
mesh_terms: D003456:Cryptorchidism / Q000150:complications; D005865:Gestational Age; D006552:Hernia, Inguinal / Q000150:complications; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008297:Male; D009679:Nuclear Family; D012044:Regression Analysis; D012307:Risk Factors; D013736:Testicular Neoplasms / Q000453:epidemiology / Q000209:etiology*; D014427:Twins