TIME TO NORMALIZATION OF SERUM TESTOSTERONE AFTER 3-MONTH LUTEINIZING-HORMONE-RELEASING HORMONE AGONIST ADMINISTERED IN THE NEOADJUVANT SETTING - IMPLICATIONS FOR DOSING SCHEDULE AND NEOADJUVANT STUDY CONSIDERATION

Purpose: A time course to serum testosterone normalization after admin istration of a single 3-month luteinizing hormone-releasing hormone (L H-RH) agonist in the neoadjuvant setting was developed. Materials and Methods: A total of 13 men with clinically localized prostate cancer w ere prospectively assessed for baseline libido, erectile function and mid morning serum testosterone. A single S-month formulation LH-RH ago nist was administered in the neoadjuvant setting before definitive tre atment with radical perineal prostatectomy in 7 men or external beam r adiotherapy in 6. Baseline and serial testosterone levels were measure d 3, 4, 6, 7, 9, 12, 15 and 18 months after injection. Symptoms relate d to acute testosterone depletion, namely hot flashes and sweats, were recorded on the same schedule. Results: After a single 3-month LH-RH agonist injection median duration of castrate level testosterone (0.2 ng./ml. or less) was 6 months. Median duration of hypogonadal symptoms (hot flashes and sweats) was 13.6 months and resolution paralleled th e gradual return of serum testosterone to baseline values. Conclusions : The 3-month formulation of LH-RH agonist administered in the neoadju vant setting provides castrate level testosterone for a longer duratio n than the product labeling suggests. If confirmed, these preliminary observations have important implications for dosing schedule and neoad juvant study consideration.