Modulation of insulin-like growth factors (IGF I-II) and IGF binding-protein 3 (IGFBP-3) through exercise training in women with breast cancer: A systematic review and meta-analysis.

Abstract

120 Background: Epidemiological data suggest that Insulin-like growth factor 1 (IGF-1) and IGF binding protein 3 (IGFBP-3) are associated with breast cancer risk, apoptosis and other carcinogenic mechanisms. This metaanalysis evaluates the effects of exercise interventions in controlling serum concentrations of Insulin-like growth factors (IGF1-IGF2) and IGFBP-3 in women with breast cancer. Methods: We incorporated the PRISMA statement. Databases of MEDLINE, Ovid, EMBASE and Cochrane Central Registers were searched to identify randomized controlled trials until March 2014, reporting effect estimates for IGF-1, IGF-2, IGFBP-3 and other secondary outcomes such as insulin, glucose and waist circumference as a body composition measure. An Inverse of variance (IV) with Mantel–Haenszel method was selected for analysis, and a random-effects models were used to assess the pooled estimates in addition to sensitivity analyses, whilst heterogeneity was evaluated using the Chi2 test (P<0.10) and I2 statistics (I2>50%).STATA 12.0 was used for metaanalysis procedures. Results: Six studies were included in the pooled analysis involving 321 patients. Effect estimates showed that exercise training improved IGF-1 (MD= -12.9, 95CI% -16.73 to -9.14, P<0.001), IGF-2 (MD= -43.4, 95CI% -58.5 to -28.3, P<0.001), IGFBP-3 (MD= -0.61, 95CI% -0.69 to -0.53, P<0.001) and waist circumference (MD= -1.133, 95CI% -2.20 to -0.05, P=0.03) in women with breast cancer. Conversely, non-significant differences were observed for Insulin (MD= 0.046, 95CI% -0.24 to 0.34, P=0.7), Glucose (MD=0.22, 95CI% -0.32 to 0.78, P=0.419) and Insulin Resistance (MD= 0.64, 95CI% -0.006 to 1.29, P= 0.06). There was no evidence of publication bias. Conclusions: Exercise is an effective and safe intervention in improving the serum concentrations of insulin like growth factors (IGF1-IGF2) and IGFBP-3 in women with breast cancer, strengthening the physiological effects of exercise in regulating cellular proliferation and apoptosis in breast cancer. Further evidences are encouraged.