Two Years Post-operative ADT Plus Radiotherapy Improves MFS, Time to Salvage Therapy in Prostate Cancer

Chris Parker, MD

The addition of 24 months of androgen deprivation therapy (ADT) to postoperative radiotherapy after radical prostatectomy provided a metastasis-free survival (MFS) benefit and improved time to salvage therapy in patients with prostate cancer, according to preliminary results from the RADICALS-HD trial (ISRCTN40814031) presented at the 2022 ESMO Congress.¹

“Up until now, doctors and patients have had to depend on opinion really to choose whether or not to have hormones with their postoperative radiotherapy, and so these results will now help doctors and patients in the future to have an evidence-based choice,” Chris Parker, MD, consultant clinical oncologist, The Royal Marsden NHS Foundation Trust, and professor, Prostate Oncology, The Institute of Cancer Research in London, said in a press briefing at the congress.

When evaluating the duration of the added therapy, 24 months of ADT improved MFS, compared with just 6 months of ADT (HR, 0.77; 95% CI, 0.61-0.97; P = .03), with 10-year MFS rates of 78% and 72%, respectively. Moreover, according to the abstract, the time to salvage therapy was delayed (HR, 0.73; 95% CI, 0.59-0.91); however, overall survival (OS) was not improved (HR 0.88; 95% CI, 0.66-1.17) with long- vs short-course therapy.

When evaluating the efficacy of ADT with radiotherapy, vs no hormone therapy, 6-month ADT failed to improve MFS (HR, 0.89; 95% CI, 0.69-1.14), with 10-year MFS rates of 79% and 80%, respectively. Similar to the long-course therapy comparison, time to salvage ADT was delayed with 6 months of ADT (HR, 0.54; 95% CI, 0.42-0.70); however, OS was not improved (HR, 0.88; 95% CI, 0.65-1.19).

“When men are getting radiotherapy for prostate cancer as their initial treatment, we know that the addition of hormone therapy improves the efficacy and survival. We also know that longer courses of hormone therapy are more effective than shorter courses of therapy,” Parker said. “However, when men are getting radiotherapy after surgery, we don’t know about the role of hormone therapy.”

Therefore, in the randomized, controlled trial, investigators aimed to evaluate the use and duration of ADT with postoperative radiation therapy by randomizing patients to receive either no ADT, 6 months of ADT (short course), or 24 months (long course) of ADT.

“So, the objectives of the trial were to test the efficacy of adding hormone therapy to postoperative radiotherapy and also to compare the efficacy of short-course and long-course hormone therapy,” Parker explained.

In 2 separate comparisons, investigators compared radiation alone vs short-course ADT (n = 1480), and also short-course ADT vs long-course ADT (n = 1523).

The trial was conducted in the UK, Canada, Denmark, and Ireland.

Key eligibility criteria were comprised of indication for radiation therapy after previous radical prostatectomy and no previous postoperative ADT.

MFS served as the primary end point. Secondary end points included time to salvage ADT and OS.

The median age of patients was 66 years. Overall, 23% of patients reported with pT3b/T4, 20% with Gleason scores 8 to 10, and a median pre-radiotherapy PSA of 0.22 ng/ml. Risk factors were more favorable in in the none-vs-short–course therapy arm, compared with the short-vs-long –course therapy arm, according to the abstract.

Median follow-up was 9 years.

“The new information from this important study will ensure clinicians can better tailor treatment for prostate cancer patients following surgery and help facilitate important discussions,” Parker said in a press release. “This will mean some receive a more effective treatment while sparing others unnecessary intervention. We already knew prostate cancer patients initially treated with radiotherapy benefitted from hormone therapy. However, we did not know whether hormone therapy would also benefit those receiving radiotherapy after prostate surgery.”

Reference

Parker CC, Clarke N, Cook A, et al. Duration of androgen deprivation therapy (ADT) with post-operative radiotherapy (RT) for prostate cancer: first results of the RADICALS-HD trial (ISRCTN40814031). Ann Oncol. 2022;33(suppl_7):S808-S869. doi:10.1016/annonc/annonc1089.