ADT Plus Radiotherapy After Radical Prostatectomy in Patients With PCa

In the RADICALS-HD trial, researchers evaluated characteristics and duration of androgen deprivation therapy (ADT) with primary radiotherapy (RT) after radical prostatectomy (RP) in patients with prostate cancer. The lead author, Chris Parker, reported that 24-month ADT increased time to salvage ADT and metastases-free survival (MFS) compared with 6-month ADT, while 6-month ADT increased time to salvage ADT, but not MFS, compared with no ADT.

The late-breaking abstract was presented at the ESMO Congress 2022. This randomized controlled trial was part of a series of trials conducted under the RADICALS protocol, which enrolled patients indicated for RT after RP with no previous postoperative ADT.

RADICALS-HD randomized 2839 patients (median patient age, 66 years) to no ADT (“None”), 6-month ADT (“Short”), and 24-month ADT (“Long”) groups. The primary outcome, MFS, was compared pairwise in None-versus-Short (1480 patients) and Short-versus-Long (1523) analyses. Additional efficacy outcomes included time to salvage ADT and overall survival (OS).

Over a median follow-up of 9 years, 6-month ADT did not improve MFS in None-versus-Short, with 79% versus 80% of patients event-free at 10 years, respectively (268 events; hazard ratio [HR], 0.89; 95% CI, 0.69-1.14). In addition, 6-month ADT did not improve OS (HR, 0.88; 95% CI, 0.65-1.19) but did delay time to salvage ADT (HR, 0.54; 95% CI, 0.42-0.70).

Comparatively, 24-month ADT improved MFS in Short-versus-Long, with 72% versus 78% of patients event-free at 10 years (313 events; HR, 0.77; 95% CI, 0.61-0.97). Likewise, 24-month ADT improved time to salvage ADT (HR, 0.73; 95% CI, 0.59-0.91) but did not improve OS (HR, 0.88; 95% CI, 0.66-1.17). The researchers noted risk comparisons were more favorable in None-versus-Short compared with Short-versus-Long.

Parker and colleagues concluded that ADT with RT after RP induced benefits in time to salvage ADT and MFS—consistent with findings on ADT with RT as an initial treatment—for patients with prostate cancer.