"Antisurvival" factor treatment for hormone refractory prostate cancer: Secondary hormonal ablation using somatostatin analogs

About 40 - 60% of the patients with prostate cancer in the hormone independent stage respond to a secondary hormonal manipulation with a temporary decrease of the serum prostate-specific antigen (PSA). PSA progression can be delayed for 4 - 8 months and the onset of a taxane-based chemotherapy with its potentially toxic side effects can be postponed. Traditionally second line antiandrogens, inhibitors of adrenal testosterone production, estrogens or progestin have been applied in secondary hormonal manipulation. Recently somatostatin analogs have been suggested for the treatment of hormone independent prostate cancer. By modulating intracellular pro-proliferative and anti-apoptotic signaling cascades somatostatin analogs influence the tumor cell micro-environment and inhibit tumor progression. In this review we focus on the mode of action and the clinical application of somatostatin analogs in the treatment of hormone- independent prostate cancer. The concept of an "anti-survival factor therapy" is discussed.