Intermittent LHRH Therapy in the Management of Castrate-resistant Prostate Cancer (CRPCa)

Abstract

Patients who develop castration-resistant prostate cancer (CRPCa) typically continue on androgen deprivation therapy (ADT). Whether these patients need to remain on ADT has not been well studied. We conducted a multicenter randomized trial to compare an intermittent versus continuous approach to ADT in CRPCa patients. Overall survival, health-related quality of life (QOL), and cost were the main endpoints. CRPCa patients were randomized 2:1 to intermittent or continuous luteinizing hormone-releasing hormone agonists (LHRHa). Patients were followed with clinical assessments, laboratory investigations, and QOL questionnaires (EORTC QLQ-C30 or PROSQOLI) every 2 months. If the serum testosterone rose above castrate levels (1.75 nmol/L), LHRHa were reinitiated. The study was designed to close if >50% of patients needed to restart ADT in the intermittent arm. Thirty-one patients were followed with a median follow-up of 26.8 months-18 in the intermittent arm and 13 in the continuous. Twelve of 18 patients on the intermittent arm were reinitiated on LHRHa at a median time of 17.9 months. There was no difference in overall or cancer-specific survival between the 2 arms. There was no statistically significant difference in QOL between the 2 arms at 0 and 12 months. The total mean costs at 24 months were significantly lower in the intermittent arm ($3135 vs. $8253 Canadian dollars, P=0.0167) compared with the continuous. The main limitation of this study is the small sample size. We have observed that intermittent ADT in patients with CRPCa, using a testosterone of >1.75 ngmol/L as a trigger to reinitiate LHRHa, results in a substantial cost savings with no negative impact on oncologic and QOL outcomes.