Trends and oncological outcome of testosterone recovery after androgen deprivation therapy in prostate cancer patients who received external beam radiotherapy.

Abstract

345 Background: Although androgen deprivation therapy (ADT) combined with external beam radiation therapy (EBRT) is standard treatment for high risk prostate cancer (PC) patients, the shift of testosterone (TST) levels after ADT and the optimal duration of ADT is unclear. TST recovery and outcome were studied in PC patients who received EBRT with ADT. Methods: Eighty-two patients who underwent EBRT with ADT for PC were retrospectively analyzed. Serum TST levels after ADT terminations were studied. Cox proportional hazard models and the Kaplan-Meier method were used for statistical analysis. Results: Median age, baseline TST, nadir TST, and duration of ADT were 73 years, 456 ng/dL, 16 ng/dL, and 26 months, respectively. ADT duration of 33 months (HR 0.13; p=0.0018), nadir TST of 20 ng/dL (HR 0.35; p=0.0112), and TST >50 ng/dL at 6 months after ADT termination (HR 0.21; p=0.0075) were significantly associated with TST recovery to normal levels (200 ng/dL) on multivariate analysis. ADT duration of 33 months (HR 0.31; p=0.0023) and nadir TST of 20 ng/dL (HR 0.38; p=0.0012) were significantly associated with TST recovery to supracastrate level (50 ng/dL) on multivariate analysis. In high risk PC patients, ADT≤ 2 year group showed shorter time to TST recovery to supracastrate levels compare to those of ADT>2 year group (HR 4.21; p=0.0022) without affecting biochemical recurrence (p=0.49) and overall survival (p=0.674). Conclusions: ADT duration of 33 months and nadir TST of 20 ng/dL predicted the TST recovery to suparacastrate levels. Less than 2 year of ADT provided better TST recovery without affecting the oncological outcome in high risk patients.[Table: see text]