Limited benefit of adding long-term ADT to post-operative radiotherapy in prostate cancer

Adding long-term androgen deprivation therapy (ADT) to post-operative radiotherapy improves metastases-free survival (MFS) compared with short-term ADT in patients with non-metastatic prostate cancer, results from the RADICALS-HD trial showed. However, most patients with short-term ADT also did well.

Current key questions for treating patients with non-metastatic prostate cancer treated with radiotherapy (with or without radical prostatectomy) are: ‘Who should receive ADT added to radiotherapy?’ and ‘What is the optimum duration of ADT?’ stated Prof. Chris Parker (The Royal Marsden Hospital, UK) presented the results. The RADICALS-HD trial (ISRCTN40814031) assessed the use and duration of ADT with post-operative radiotherapy [1,2].

The trial enrolled nearly 3,000 patients who had undergone postoperative radiotherapy (adjuvant or early salvage). 1,480 of these participants were randomised 1:1 to receive short-term (6 months) versus no ADT and 1,523 participants were randomised 1:1 to receive short-term versus long-term ADT (24 months). The participants’ characteristics within the two parts of the trial were well balanced, however, participants in the ‘none versus short-term’ ADT part had less aggressive disease than those selected for the “short- versus long-term’ ADT part. The median follow-up was 9 years in both parts. The primary outcome was metastasis-free survival (MFS). Secondary outcomes included time to salvage ADT and overall survival (OS).

In the ‘none versus short-term’ ADT part, 6 months of ADT did not improve MFS (80% vs 79% at 10 years; HR 0.86; P=0.35;) but delayed time to salvage ADT (HR 0.54; 95% CI 0.42–0.70). In the ‘short- versus long-term’ ADT part, 24 months of ADT improved MFS compared to 6 months of ADT (78% vs 72% at 10-years; HR 0.77; P=0.03;) and delayed time to salvage ADT (HR 0.73; 95% CI 0.59–0.91). There was no interaction between the treatment effect and either the baseline prostate-specific antigen (PSA) or comorbidity score. OS data were not yet mature in either part of the trial.

“When added to post-operative radiotherapy for prostate cancer, long-term ADT improved MFS and improved time to salvage ADT, compared with short-term ADT. Short-term ADT did not improve MFS, but delayed time to salvage ADT, compared with no ADT. The effect size appeared consistent across all pre-specified subgroups,” summarised Dr Parker. Of note, the RADICALS-HD trial started 15 years ago and the management of patients has changed since then.

1. Parker CC, et al. Clin Oncol (R Coll Radiol). 2022;34(9):593–597.
2. Parker CC, et al. Duration of androgen deprivation therapy (ADT) with post-operative radiotherapy (RT) for prostate cancer: First results of the RADICALS-HD trial (ISRCTN40814031). Abstract LBA9, ESMO Congress 2022, 09–13 September, Paris, France.

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Posted on 17 November, 20228 February, 2024