Prolonged response to a single androgen suppression phase in a subpopulation of prostate cancer patients

Abstract

Background: In an intermittent androgen suppression therapy (IAS) trial we observed regular cycles of tumor suppression and regrowth in the majority of patients (17±2.6 month), with a subpopulation of patients (14 of 72) exhibiting a prolonged response of 28±7 month (range 18–64+ month) to the first eight-month androgen suppression cycle.Purpose: To compare clinical data and laboratory tests (testosterone, prostate-specific antigen, and tissue polypeptidespecific antigen) of matched IAS patients showing either regular treatment cycles (n=16) or prolonged response (n=14).Results: Periods of androgen suppression resulted in reversible reduction of serum testosterone (<1 nmol/l), PSA (<1 ng/ml) indicating partial growth arrest and apoptotic regression of the tumors. The long-term response subgroup showed significantly lower mean values of tumor gradings, of pretreatment PSA values (11.36±4.54 vs. 47.5±12.4 ng/ml PSA), of PSA nadirs during androgen suppression (0.5 vs. 1 ng/ml PSA), and of overall testosterone values (3.9±1.14 vs. 6.6±1.18 mmol/l pretreatment) associated with low TPS values.Conclusions: Patients exhibiting prolonged response to a single cycle of androgen suppression during IAS are characterized by a lower tumor burden, slow growing and less agressive tumors, lower testosterone serum concentrations and lower absolute PSA nadirs during androgen suppression compared to a matched control group of short-term responders.