title: The insulin-like growth factor system is modulated by exercise in breast cancer survivors: a systematic review and meta-analysis.
abstract: Insulin-like growth factors (IGF´s) play a crucial role in controlling cancer cell proliferation, differentiation and apoptosis. Exercise has been postulated as an effective intervention in improving cancer-related outcomes and survival, although its effects on IGF´s are not well understood. This meta-analysis aimed to determine the effects of exercise in modulating IGF´s system in breast cancer survivors.
  
  
  
  Databases of PuMed, EMBASE, Cochrane Central Register of Controlled Trials, EMBASE, ClinicalTrials.gov, SPORTDiscus, LILACS and Scopus were systematically searched up to November 2014. Effect estimates were calculated through a random-effects model of meta-analysis according to the DerSimonian and Laird method. Heterogeneity was evaluated with the I (2) test. Risk of bias and methodological quality were evaluated using the PEDro score.
  
  
  
  Five randomized controlled trials (n = 235) were included. Most women were post-menopausal. High-quality and low risk of bias were found (mean PEDro score = 6.2 ± 1). Exercise resulted in significant improvements on IGF-I, IGF-II, IGFBP-I, IGFBP-3, Insulin and Insulin resistance (P < 0.05). Non-significant differences were found for Glucose. Aerobic exercise improved IGF-I, IGFBP-3 and Insulin. No evidence of publication bias was detected by Egger´s test (p = 0.12).
  
  
  
  Exercise improved IGF´s in breast cancer survivors. These findings provide novel insight regarding the molecular effects of exercise on tumoral microenvironment, apoptosis and survival in breast cancer survivors.
authors: Centro de Estudios en Medición de la Actividad Física (CEMA), Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, DC, Colombia.
authors: José Francisco
authors: JF
authors: Meneses-Echávez
authors: Departamento de Enfermería. Facultad de Ciencias de la Salud, Universidad de Granada, Granada, Spain.
authors: Emilio González
authors: EG
authors: Jiménez
authors: Departamento de Enfermería. Facultad de Ciencias de la Salud, Universidad de Granada, Granada, Spain.
authors: Jacqueline Schmidt
authors: JS
authors: Río-Valle
authors: Centro de Estudios en Medición de la Actividad Física (CEMA), Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, DC, Colombia.
authors: Jorge Enrique
authors: JE
authors: Correa-Bautista
authors: Department of Health Sciences Public, University of Navarra, Pamplona, Spain.
authors: Mikel
authors: M
authors: Izquierdo
authors: Centro de Estudios en Medición de la Actividad Física (CEMA), Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, DC, Colombia. robin640@hotmail.com.
authors: Robinson
authors: R
authors: Ramírez-Vélez
mesh_terms: D015415:Biomarkers; D001943:Breast Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism* / Q000628:therapy; D003131:Combined Modality Therapy; D015444:Exercise; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D009367:Neoplasm Staging; D017594:Publication Bias; D013002:Somatomedins / Q000378:metabolism*; D017741:Survivors
chemical_list: D015415:Biomarkers; D018972:Insulin-Like Growth Factor Binding Protein 3; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II
keywords: Breast cancer; Exercise; Insulin-Like Growth Factor Binding Proteins; Tumor Microenvironment