Lag time.

Top Line: Does the sequencing of short-course androgen deprivation therapy (ADT) with radiation influence testosterone recovery and/or biochemical recurrence?

The Study: Those are the questions asked by this secondary analysis of a randomized trial where men received 2 months of ADT (bicalutamide and goserelin) concurrent to radiation with 4 additional months of either neoadjuvant or adjuvant ADT. It took an average of 18 months after initiating ADT (i.e., 12 months after finishing) for complete testosterone recovery, defined as ≥10.5 nmol/L. At 6 months after finishing ADT, 20% of men had supra-castrate testosterone recovery at ≥1.7 nmol/L, with 90% of these being complete testosterone recovery. Most men experienced recovery between 6-12 months after finishing ADT, with a 70% rate of complete recovery by 18 months. Overall, the sequence of ADT and radiation had no effect on full testosterone recovery. Furthermore, the kinetics of testosterone recovery had no effect on the risk of biochemical recurrence. Predictors of longer time to recovery were older age, diabetes, and lower baseline testosterone. Compare all this to the HERO trial, where men on the novel oral GnRH antagonist relugolix had an average testosterone of 288.4 ng/dL (~10.0 nmol/L) just 3 months after stopping ADT.

TBL: It takes, on average, one year to achieve full testosterone recovery after short-course combined ADT with a non-steroidal anti-androgen and an LHRH agonist, a lag that doesn’t appear to influence the risk of prostate cancer recurrence. | Roy, Int J Radiat Oncol Biol Phys 2020