Does Oral Antiandrogen Use Before Leuteinizing Hormone-releasing Hormone Therapy in Patients With Metastatic Prostate Cancer Prevent Clinical Consequences of a Testosterone Flare?

Objectives: To investigate whether oral antiandrogen therapy before initiation of leuteinizing hormone-releasing hormone (LHRH) agonists was associated with fewer clinical flares. LHRH agonists are associated with initial testosterone rises that may cause clinical disease flares in men with metastatic prostate cancer. Methods: We identified newly diagnosed metastatic prostate cancer patients treated in Veterans Affairs Hospitals from 2001-2004 with LHRH agonists with or without prior antiandrogen therapy. We assessed spinal cord compression, radiation therapy, fractures, bladder outlet obstruction, and narcotic prescriptions for pain within 30 days of starting LHRH therapy. Results: Of 1566 metastatic prostate cancer patients treated with LHRH agonists, 1245 (79.5%) patients received oral antiandrogens before initiating LHRH agonist treatment. Hispanic men, married patients, and those without prior cancer were treated less often with oral antiandrogens (all P ≤ .05). Complication rates did not differ by receipt of oral antiandrogens (all P ≥ .17). Spinal cord compression and pathologic fractures were extremely rare whether antiandrogens were used or not. In adjusted analysis, there was no decrease in odds of any event for treatment with an antiandrogen within 6 days (OR, 1.04, 95% CI, 0.78-1.40) or ≥ 7 days (OR, 0.95, 95% CI, 0.72-1.25) before LHRH agonist treatment. Conclusions: Antiandrogen therapy before LHRH agonists in metastatic prostate cancer was not associated with differences in fractures, spinal cord compression, bladder outlet obstruction, or narcotic prescriptions. Rates of spinal cord compression or fracture were < 1% in the first 30 days after beginning LHRH agonist therapy regardless of antiandrogen use.