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 administration of a single 3-month luteinizing hormone-releasing hormone (LH-RH) agonist in the neoadjuvant setting was developed.
MATERIALS AND METHODS: A total of 13 men with clinically localized prostate cancer were prospectively assessed for baseline libido, erectile function and mid morning serum testosterone. A single 3-month formulation LH-RH agonist was administered in the neoadjuvant setting before definitive treatment with radical perineal prostatectomy in 7 men or external beam radiotherapy in 6. Baseline and serial testosterone levels were measured 3, 4, 6, 7, 9, 12, 15 and 18 months after injection. Symptoms related 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 the gradual return of serum testosterone to baseline values.
CONCLUSIONS: The 3-month formulation of LH-RH agonist administered in the neoadjuvant setting provides castrate level testosterone for a longer duration than the product labeling suggests. If confirmed, these preliminary observations have important implications for dosing schedule and neoadjuvant study consideration.