(UroToday.com) On the first day of the American Society for Clinical Oncology (ASCO) Genitourinary Cancer Symposium 2023 focussing on prostate cancer, Dr. Wee Loon Ong presented in Poster Session A the results of an individual patient data meta-analysis from the MARCAP consortium aimed at assessing testosterone recovering following androgen suppression (androgen deprivation therapy; ADT) and prostate radiotherapy.
ADT of various durations has become standard of care for many patients receiving primary radiation therapy for prostate cancer. The kinetics of testosterone recovery (TR) following this androgen suppression may vary widely between patients and has important implications for patients’ quality of life. In this analysis, the authors sought to identify factors affecting the time to TR following ADT use.
To do so, they 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 was available. They examined the time to non-hypogonadal TR (NHTR) (>8.0nmol/L) and time to full TR (FTR) (>10.5nmol/L) from the date of first available testosterone at trial enrolment to the date of TR using the Kaplan-Meier method. Further, they assessed the effect of interactions between duration of ADT and patients’ age on TR was evaluated.
They identified 1439 men with non-castrate testosterone at baseline (>1.7nmol/L) who met the inclusion criteria for analysis. Among these 1439 men, 220, 765 and 454 men had 3-, 6-, and 18-months of ADT.
As of the last follow-up, 959 (67%) men had FTR. 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.
Among a 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. However, the authors found no evidence of interaction between the effect of ADT duration on time to FTR and age (interaction P=0.3 for entire cohort).
They therefore concluded that, in this the largest pooled analysis of prospectively collected serial testosterone data from randomized trials, a substantial delay in FTR in men receiving longer durations of ADT is common. Approximately one-third of the men did not achieve FTR, which may have life-long impact on quality of life.
Presented by: Wee Loon Ong, MBBS | Odette Cancer Centre, Sunnybrook Health Sciences Centre