Circulating free insulin-like growth factor-I and prostate cancer: a case-control study nested in the European prospective investigation into cancer and nutrition
Tuck Seng Cheng,
Urwah Noor,
Eleanor Watts,
Michael Pollak,
Ye Wang,
James McKay,
Joshua Atkins,
Giovanna Masala,
Maria-Jose Sánchez,
Antonio Agudo,
Jesús Castilla,
Dagfinn Aune,
Sandra M. Colorado-Yohar,
Luca Manfredi,
Marc J. Gunter,
Valeria Pala,
Andreas Josefsson,
Timothy J. Key,
Karl Smith-Byrne,
Ruth C. Travis
Affiliations
Tuck Seng Cheng
Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford
Urwah Noor
Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford
Eleanor Watts
Division of Cancer Epidemiology and Genetics, National Cancer Institute
Michael Pollak
Oncology Department, McGill University and Segal Cancer Centre, Jewish General Hospital
Ye Wang
Oncology Department, McGill University and Segal Cancer Centre, Jewish General Hospital
James McKay
Genomic Epidemiology Branch, International Agency for Research on Cancer
Joshua Atkins
Genomic Epidemiology Branch, International Agency for Research on Cancer
Giovanna Masala
Cancer Risk Factors and Life-Style Epidemiology Unit, Institute for Cancer Research, Prevention and Clinical Network (ISPRO)
Maria-Jose Sánchez
Escuela Andaluza de Salud Pública (EASP)
Antonio Agudo
Unit of Nutrition and Cancer, Catalan Institute of Oncology - ICO, L’Hospitalet de Llobregat
Jesús Castilla
Instituto de Salud Pública de Navarra – IdiSNA
Dagfinn Aune
Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London
Sandra M. Colorado-Yohar
Department of Epidemiology, Murcia Regional Health Council-IMIB
Luca Manfredi
Centre for Biostatistics, Epidemiology, and Public Health (C-BEPH), Department of Clinical and Biological Sciences, University of Turin
Marc J. Gunter
Nutrition and Metabolism Branch, International Agency for Research on Cancer (IARC- WHO)
Valeria Pala
Epidemiology and Prevention Unit, Department of Research, Fondazione IRCCS Istituto Nazionale dei Tumori
Andreas Josefsson
Department of Urology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg
Timothy J. Key
Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford
Karl Smith-Byrne
Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford
Ruth C. Travis
Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford
Abstract Background Circulating total insulin-like growth factor-I (IGF-I) is an established risk factor for prostate cancer. However, only a small proportion of circulating IGF-I is free or readily dissociable from IGF-binding proteins (its bioavailable form), and few studies have investigated the association of circulating free IGF-I with prostate cancer risk. Methods We analyzed data from 767 prostate cancer cases and 767 matched controls nested within the European Prospective Investigation into Cancer and Nutrition cohort, with an average of 14-years (interquartile range = 2.9) follow-up. Matching variables were study center, length of follow-up, age, and time of day and fasting duration at blood collection. Circulating free IGF-I concentration was measured in serum samples collected at recruitment visit (mean age 55 years old; standard deviation = 7.1) using an enzyme-linked immunosorbent assay (ELISA). Conditional logistic regressions were performed to examine the associations of free IGF-I with risk of prostate cancer overall and subdivided by time to diagnosis (≤ 14 and > 14 years), and tumor characteristics. Results Circulating free IGF-I concentrations (in fourths and as a continuous variable) were not associated with prostate cancer risk overall (odds ratio [OR] = 1.00 per 0.1 nmol/L increment, 95% CI: 0.99, 1.02) or by time to diagnosis, or with prostate cancer subtypes, including tumor stage and histological grade. Conclusions Estimated circulating free IGF-I was not associated with prostate cancer risk. Further research may consider other assay methods that estimate bioavailable IGF-I to provide more insight into the well-substantiated association between circulating total IGF-I and subsequent prostate cancer risk.
