Re: Insulin-Like Growth Factor-I (IGF-I) and IGF Binding Protein-3 as Predictors of Advanced-Stage Prostate Cancer

A recent study (1) suggested that elevated plasma levels of insulin-like growth factor-I (IGF-I) were a predictor of advanced-stage prostate cancer. We have studied IGF-I in prostate cancer and have found no relationship to dis-ease stage. We studied IGF-I in a group of 126 men with prostate cancer and benign prostatic hypertrophy (BPH). Partici-pants in our study were found through urology and radiation oncology clinics, and all eligible patients were asked to take part. All cancer patients had ini-tially been diagnosed on the basis of lev-els of prostate-specific antigen (PSA) or abnormal physical examination. All men with BPH had had negative pros-tate biopsy examinations. Histologic confirmation of cancer diagnosis was also obtained for all subjects. All par-ticipants gave written informed consent. All staging of cancer cases was clinical, because almost all of the patients were to receive 125I seed implant therapy. Serum IGF-I was measured by use of the Nichols Advantage, an automated che-miluminescent immunoassay analyze