Original Contribution Insulin-like Growth Factor 1, Insulin-like Growth Factor-Binding Protein 3, and

Studies have consistently shown that taller men are at increased risk of testicular germ-cell tumors. Thus, it is plausible that factors associated with height may also influence risk of these tumors. The authors examined associations between testicular germ-cell tumor risk and circulating concentrations of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor-binding protein 3 (IGFBP-3) among 517 cases and 790 controls from the US Servicemen’s Testicular Tumor Environmental and Endocrine Determinants (STEED) Study (2002–2005). Odds ratios and 95 % confidence intervals were estimated using logistic regression models, adjusting for age, race/ ethnicity, height, and body mass index. All tests of significance were two-sided. Overall, there were no associations between IGF-1 or IGFBP-3 concentrations and risk of testicular germ-cell tumors (p> 0.05). However, when cases were separated by histologic type, there was a suggestion of a reduction in seminoma risk associated with the highest concentrations of IGF-1 as compared with the lowest concentrations (odds ratio 0.66, 95 % confidence interval: 0.40, 1.09). Although there were no overall associations with insulin-like growth factor, contrary to expec-tation, there was a suggestion that IGF-1 concentrations may be inversely associated with risk of seminoma. hormones; insulin-like growth factor binding protein 3; insulin-like growth factor I; testicular neoplasms Abbreviations: IGF, insulin-like growth factor; IGFBP-3, insulin-like growth factor-binding protein 3; STEED, US Servicemen’s Testicular Tumor Environmental and Endocrine Determinants