Testosterone recovery as biomarker for overall and cause-specific survival in combined treated patients with high-risk and locally advanced prostate cancer.

Abstract

188 Background: Androgen deprivation therapy (ADT) can cause considerable toxicity and may influence outcome. The study assessed the impact of testosterone recovery (TR) on survival after ADT and definitive radiotherapy in two independent cohorts. Methods: Two hundred and forty-four patients (high risk JHH cohort N=106, T1c-T3N0M0 [A], locally advanced OUH cohort N=138, T1c-T4N0-1M0 [B]) with adenocarcinoma of the prostate were included in this retrospective analysis. Short and long-term ADT was given (median 12 months A, 24 months B, respectively,) and along with conformal external beam radiation 76-80 Gy given to the prostate in cohort A, 74 Gy prescribed in cohort B and 46-50 Gy to the whole pelvis. Testosterone levels were measured at the end of ADT and at biochemical relapse. TR was defined as ≥ 9 nmol/L. Kaplan Meier plots were generated for overall survival (OS) and cause-specific survival (CSS) stratified by TR, in addition to patient characteristics median time to TR and FU were calculated. Results: The median age in the A cohort was 66.7 years and 64.7 years in the B group. FU was 6 years for A and 8 years in B. Patients in group A received median ADT of 12 months and 24 months in group B. The median time to TR was 1.6 yr in A and 2.5 yrs in B, respectively. Patients in group A stratified to TR showed no difference in overall survival (p=0.92)), on contrary, patients in group B showed improved overall survival depending on TR (Fig. 1, KM plot, 10 year OS 75.3% vs 59.9% p=0.034). CSS was seemed to trend towards improvement with TR for cohort A (p=0.19) and was improved in cohort B (p=0.022). The Univariate ADT length, age, and RT dose was associated with time to TR, but on multivariate analysis only longer ADT time (p = 0.03) was significantly associated with time to TR. Conclusions: TR was associated with improved OS in patients with unfavorable locally advanced disease a finding not seen in patients with high-risk disease.