A meta-analysis of the risk of boys with isolated cryptorchidism developing testicular cancer in later life
- Stefanie Zhao Lin Lip1,
- Louise Elizabeth Denheen Murchison1,
- Paul Stephen Cullis2,
- Lindsay Govan3,
- Robert Carachi4
- 1School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- 2Department of Neonatology, Royal Hospital for Sick Children, Glasgow, UK
- 3Health Economics and Health Technology Assessment, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
- 4Department of Surgical Paediatrics, Royal Hospital for Sick Children, Glasgow, UK
- Correspondence to Professor Robert Carachi, Department of Surgical Paediatrics, Royal Hospital for Sick Children, Yorkhill, Glasgow G3 8SJ, UK;
Contributors SZLL, LEDM: performed literature search; applied inclusion and exclusion criteria to articles identified in the literature search; collected data for meta-analysis; performed statistical analysis; designed figures; wrote the manuscript. PSC: applied inclusion and exclusion criteria to articles identified in the literature search; collected data for meta-analysis; wrote the manuscript. LG: conceived the statistical method and supervised interpretation of the statistical analysis. RC: imagined the study concept; applied inclusion and exclusion criteria to articles identified in the literature search; supervised writing of the manuscript and overall project.
- Received 12 April 2012
- Revised 24 September 2012
- Accepted 3 October 2012
- Published Online First 28 November 2012
Background Significant variability exists for the relative risk (RR) of testicular malignancy in isolated cryptorchidism.
Objective To perform a meta-analysis to clarify the true magnitude of this risk, allowing clinicians to better counsel patients and their families.
Setting Secondary research conducted by undergraduate researchers, clinical academics and a clinical statistician.
Design, data sources, and methods A search of the English literature was performed for studies relating to testicular cancer and cryptorchidism, published between 1 January 1980 and 31 December 2010, using Embase and Medline databases. 735 papers were identified and analysed by four authors independently in accordance with our inclusion and exclusion criteria. Studies reporting an association between cryptorchidism and subsequent development of testicular malignancy were included. Genetic syndromes or other conditions which predisposed to the development of cryptorchidism were excluded. Pooled estimates and 95% CIs for the RRs were calculated.
Results Nine case–control studies and three cohort studies were selected. The case–control studies included 2281 cases and 4811 controls. Cohort studies included 2 177 941 boys, with a total of 345 boys developing testicular cancer (total length of follow-up was 58 270 679 person-years). The pooled RR was 2.90 (95% CI 2.21 to 3.82) with significant heterogeneity (p<0.00001; I2=89%).
Conclusion Boys with isolated cryptorchidism are three times more likely to develop testicular cancer. The limitations of this study must be acknowledged, in particular, possible publication bias and the lack of high-quality evidence focusing on the risk of malignancy in boys with isolated cryptorchidism.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.