Unrecognized Kinetics of Serum Testosterone: Impact on Short-Term Androgen Deprivation Therapy for Prostate Cancer

Purpose

To evaluate the kinetics of serum testosterone (T) recovery following short-term androgen deprivation therapy (ADT), as the understanding thereof is essential for the proper management of prostate cancer (PCa), especially intermittent ADT.

Materials and Methods

This prospective analysis included male sex offenders who voluntarily received leuprolide acetate in order to alleviate sexual aberrance. Thirty-three and 25 patients who received 3 and 6 months of ADT were assigned to Group A and Group B, respectively. Serum T levels were obtained every week during the on-cycle period, then monthly during the off-cycle period for at least 12 months.

Results

The kinetics of serum T during the on-cycle period were similar in both groups. After flare reaction at week 2, a nadir of 0.45±0.29 ng/mL was achieved. In Group A, an abrupt rebound-upsurge was observed during the first 2 month off-cycle period, which surpassed the baseline level and reached a plateau level of 8.74±2.11 ng/mL during the flare (p<0.001). This upsurge was followed by a gradual decline back to baseline over the following 10 months. In Group B, a gradual increase was observed, and a baseline level of 7.26±1.73 ng/mL was reached at 5 months. Thereafter, an ongoing upsurge that surpassed baseline levels was observed until 12 months (8.81±1.92 ng/mL; p=0.002).

Conclusion

The kinetics of serum T recovery during the off-cycle period varied according to the duration of ADT. Serum T should be monitored beyond normalization, as an excessive rebound may improve quality-of-life, but hamper the treatment efficacy of PCa.