Testosterone Recovery Following Androgen Suppression and Prostate Radiotherapy (TRANSPORT): Individual patient data meta-analysis from the MARCAP Consortium.

366 Background: The kinetics of testosterone recovery (TR) vary following cessation of androgen deprivation therapy (ADT) of various durations when given in combination with radiotherapy for prostate cancer. Time to TR will impact on quality of life. We aim to identify factors affecting the time to TR following ADT use. Methods: We included trials of prostate radiotherapy and ADT in the Meta-Analysis of Randomized trials in Cancer of the Prostate (MARCAP) consortium for which prospectively collected serial testosterone data is available. Time to non-hypogonadal TR (NHTR) (>8.0nmol/L) and time to full TR (FTR) (>10.5nmol/L) were estimated from the date of first available testosterone at trial enrolment to the date of TR using the Kaplan-Meier method. The effect of interactions between duration of ADT and patients’ age on TR was evaluated. Results: There were 1439 men with non-castrate testosterone at baseline (>1.7nmol/L) who met the inclusion criteria for analysis, of which 220, 765 and 454 men had 3-, 6-, and 18-months of ADT. There were 959 (67%) men who had FTR at last follow-up. For men who had 3-, 6-, and 18-months of ADT, the median time (range) to NHTR were 5.5 (1.6-76.3), 12.2 (0.8-53.6), and 30.1 (2.8-90.4) months respectively, while the median time (range) to FTR were 6.2 (1.8-75.7), 15.2 (0.8-86.0), and 36.0 (18.1-85.5) months respectively. In the subset of 1160 men who had normal testosterone at baseline (>10.5nmol/L), 851 (69%) men had FTR, with a median time (range) to FTR of 5.5 (1.8-75.7), 12.7 (1.8-86.0), and 30.8 (18.1-84.1) months for men who had 3-, 6- and 18-months ADT, respectively. For any given duration of ADT, men aged above 65 years were less likely to have FTR compared to those aged under 65 years – HR=0.67 (95%CI=0.46-0.99), HR=0.80 (95%CI=0.67-0.96), HR=0.64 (95%CI=0.51-0.81) for men who had 3-, 6-, and 18-months ADT respectively. There was no evidence of interaction between the effect of ADT duration on time to FTR and age (interaction P=0.3 for entire cohort). Conclusions: This is the largest pooled analysis of prospectively collected serial testosterone data from randomized trials, indicating substantial delay in FTR in men receiving longer durations of ADT. Approximately one-third of the men did not achieve FTR, which may have life-long impact on quality of life.