title: Cryptorchidism and testicular germ cell tumors: comprehensive meta-analysis reveals that association between these conditions diminished over time and is modified by clinical characteristics.
abstract: BACKGROUND
  Risk of testicular germ cell tumors (TGCT) is consistently associated with a history of cryptorchidism (CO) in epidemiologic studies. Factors modifying the association may provide insights regarding etiology of TGCT and suggest a basis for individualized care of CO. To identify modifiers of the CO-TGCT association, we conducted a comprehensive, quantitative evaluation of epidemiologic data.
  
  
  METHODS
  Human studies cited in PubMed or ISI Web of Science indices through December 2011 and selected unpublished epidemiologic data were reviewed to identify 35 articles and one unpublished dataset with high-quality data on the CO-TGCT association. Association data were extracted as point and 95% confidence interval estimates of odds ratio (OR) or standardized incidence ratio (SIR), or as tabulated data. Values were recorded for each study population, and for subgroups defined by features of study design, CO and TGCT. Extracted data were used to estimate summary risk ratios (sRR) and evaluate heterogeneity of the CO-TGCT association between subgroups.
  
  
  RESULTS
  The overall meta-analysis showed that history of CO is associated with four-fold increased TGCT risk [RR = 4.1(95% CI = 3.6-4.7)]. Subgroup analyses identified five determinants of stronger association: bilateral CO, unilateral CO ipsilateral to TGCT, delayed CO treatment, TGCT diagnosed before 1970, and seminoma histology.
  
  
  CONCLUSIONS
  Modifying factors may provide insight into TGCT etiology and suggest improved approaches to managing CO. Based on available data, CO patients and their parents or caregivers should be made aware of elevated TGCT risk following orchidopexy, regardless of age at repair, unilateral vs. bilateral non-descent, or position of undescended testes.
authors: Keck School of Medicine, University of Southern California Los Angeles, CA, USA ; City of Hope National Medical Center Duarte, CA, USA ; St. Joseph Hospital Orange, CA, USA.
authors: Kimberly
authors: K
authors: Banks
authors: Ellenie
authors: E
authors: Tuazon
authors: Kiros
authors: K
authors: Berhane
authors: Chester J
authors: CJ
authors: Koh
authors: Roger E
authors: RE
authors: De Filippo
authors: Andy
authors: A
authors: Chang
authors: Steve S
authors: SS
authors: Kim
authors: Siamak
authors: S
authors: Daneshmand
authors: Carol
authors: C
authors: Davis-Dao
authors: Juan P
authors: JP
authors: Lewinger
authors: Leslie
authors: L
authors: Bernstein
authors: Victoria K
authors: VK
authors: Cortessis
keywords: cryptorchidism; meta-analysis; non-seminoma; seminoma; testicular neoplasms