Insulin-like growth factor-I and prostate cancer: a meta-analysis

Some, but not all, epidemiological found have shown that high circulating levels of insulin-like growth factor-1 (IGF-1) are associated with an increased risk of prostate cancer. We performed a meta-analysis on all the studies reported so far to evaluate this association. In our Medline search, 14 case-control studies were identified. A standard protocol abstracted information for each study. Hedges' standardized mean difference (HSMD) and odds ratio (OR) were used to estimate the effect of IGF-1 and IGF-binding proteins (IGFBP-3). The combined data showed that circulating levels of IGF-l were significantly higher in prostate cancer patients (HSMD = 0.194). The OR for prostate cancer was 1.47 (95% confidence interval (CI) 1.23-1.77) among men with high IGF-1 compared to those with low IGF-1. The OR was 1.26 (95% Cl 1.03-1.54) for IGFBP-3. Circulating levels of IGF-1 and IGFBP-3 are likely to be higher in prostate cancer patients than in the controls. These findings support the suggestion that high IGF-1 and IGFBP-3 are associated with an increased risk of prostate cancer. (C) 2001 Cancer Research Campaign http://www.bjcancer.com.