Increased concentrations of insulin-like growth factor I (IGF-I) and decreased insulin-like growth factor binding protein 3 (IGFBP-3) in serum have been proposed as markers of prostate cancer (CaP). The evidence for this, however, is contradictory. We assayed serum for IGF-I, IGFBP-3 and prostate-specific antigen (PSA) in patients with CaP and benign prostatic hyperplasia (BPH) and in healthy controls (HC). The mean ± SD concentration of IGF-I in CaP (98.3 ± 39.3 ng/mL; n=15) was lower than in BPH (119 ± 31.1 ng/mL; n=24) and HC (119 ± 36.1 ng/mL; n=46), but the differences between the three groups were not statistically significant (p>0.05). The mean IGFBP-3 concentrations in CaP (2691 ± 1105 ng/mL; n=16; p=0.029) and BPH (2618 ± 816 ng/mL; n= 26; p=0.006) patients were significantly lower than that of the HC (3119 ± 618 ng/mL; n=59), but the difference between the two groups of patients was not significant (p>0.05). PSA concentrations in CaP (median=80.8 ng/mL; n=25) were significantly higher than those in BPH (median=8.6 ng/mL; n=39) (p<0.001). Ninety-six percent of CaP and 72% of BPH patients had PSA concentrations >4.0 ng/mL; the proportions of patients with concentrations exceeding 20 ng/mL were 76% and 10%, respectively. We conclude that IGF-I and IGFBP-3 are inferior to PSA for CaP detection.
RESPONSE: Re: Insulin-Like Growth Factor-I (IGF-I) and IGF Binding Protein-3 as Predictors of Advanced-Stage Prostate Cancer