036 Testosterone Recovery Profiles after Cessation of Androgen Deprivation Therapy (ADT)

Abstract

It has been demonstrated that the combination use of ADT improves overall and cancer-specific survival in men with unfavorable prostate cancer (PCa). After cessation of ADT, testosterone (T) levels are expected to recover from castrate to normal levels. However, very little is known about T recovery profiles in this population, and many patients remain on castrate levels indefinitely. The aim of this study was to evaluate T recovery after cessation of ADT in PCa patients. We reviewed our prospectively maintained database for PCa patients who received ADT therapy at our institution. Serum early morning total T (TT) levels were measured at baseline and periodically after ADT cessation. Multivariable time-to-event analysis (Cox proportional hazards) was performed to determine predictors of TT recovery after ADT cessation and included the following variables: patient age, baseline T level, and duration of ADT. 1641 men with a mean age of 66 (43-94) years were included. Primary treatment for PCa was RP in 36%, while the remainder had either RT or primary ADT. The majority received a GnRH agonist as mainstay for ADT. Mean duration of ADT was 28.8±39 months [0.5 to 324]. Distribution of ADT exposure was: <6 months (m) 33%, 6-12m 19%, 12-24m 16%, >24m 33%. Median follow-up was 47.5±45 months. Mean TT values were: baseline 358 ng/dl, 6-12m post ADT cessation 96 ng/dl, 12-18 174 ng/dl, 18-24m 228 ng/dl, >24m 273 ng/dl. At last follow-up: 77% men had TT level above castrate level, 45% had TT >300ng/dl and 39% returned to pre-treatment TT level. On multivariable analysis age over 65 years (HR 2.01, 95%CI 1.48-2.71, P<0.0001), ADT duration of 6 months or greater (HR 1.42, 95%CI 1.07-1.90, P=0.02), and baseline T of 400 ng/dl or more (HR 1.80, 95%CI 1.36-2.40, P<0.0001) were all significantly associated with a slower recovery time.