Prostatic fluid-free insulin-like growth factor-1 in relation to prostate cancer

Objectives To establish the feasibility of measuring free insulin-like growth factor-1 (IGF-1) in prostatic fluid and to determine if there is a difference in free IGF-1 levels in the prostatic fluid of patients with prostatic adenocarcinoma and in normal men. Patients and methods Prostatic fluid samples were collected from men with histologically confirmed prostate cancer and from control subjects with no malignancy. Prostatic fluid and serum free IGF-1 levels were measured in duplicate by radioimmunoassay, and the differences analysed using the Mann-Whitney U-test and Pearson correlation. Results Prostatic fluid free IGF-1 concentrations did not differ significantly (P=0.23) and there was no difference in serum free IGF-1 levels between the groups. While serum PSA level was significantly correlated with age (P<0.001) the free IGF-1 level of prostatic fluid was not. There was also no correlation between prostatic fluid free IGF-1 and serum PSA levels. Conclusions Free IGF-1 can be detected in prostatic fluid with acceptable sensitivity. However, the free IGF-1 level in prostatic fluid does not help to detect patients with prostate cancer and is not a tumour marker.