[Quantitative analysis of IGF-1 and its application in the diagnosis of prostate cancer].

Objective: To quantify the level of insulin-like growth factor (IGF-1) in serum and investigate its role in the diagnosis of prostate cancer.

Methods: IGF-1 immunoradiometric assay (IRMA) was set up and used to determine serum IGF-1 level in patients with prostate cancer (n = 81), benign prostate hyperplasia (BPH, n = 55), uroepithelial tumor (n = 32) and healthy male controls (n = 84). Furthermore, the levels of IGF-1 and prostate-specific antigen (PSA) in 38 patients with BPH were determined every three months for one year.

Results: Linearity was well demonstrated for IGF-1 in the range of 8-1000 ng (r = 0.98), the lowest limit for detecting IGF-1 being 2 mg/L and the mean recovery for detecting IGF-1 being 94.5%. The within-replicate coefficient of variance (CV) of IGF-1 detection was 7.2% for a higher level (382.4 mg/L) and 4.2% for a low level (32.5 mg/L) of IGF-1. Insulin, growth factor or IGF-2 did not interfere with the detection of IGF-1 (< 3 ml/L). There was high level of IGF-1 in patients with prostate cancer than in healthy controls, patients with BPH and uroepithelial tumor (P < 0.05); the odds ratio and its 95% confidence intervals were 2.86 and 1.38-5.34, respectively; the specificity and sensitivity of IGF-1 determination were 0.68 and 0.58, respectively; furthermore, the level of IGF-1 was increased during the development of prostate cancer.

Conclusions: These findings demonstrate that IGF-1 may serve prospectively as an important tumor marker in the diagnosis and prediction of prostate cancer.