Episode 17: Prostate irradiation for men with newly-diagnosed, metastatic castration-sensitive prostate cancer: new insights from PEACE-1

In this new episode of ‘What’s New Doc’ in Prostate cancer, Prof Bertrand Tombal from the Cliniques Universitaires Saint-Luc in Brussels, and Prof Steven Joniau from the University Hospitals Leuven discuss the impact of the PEACE-1 trial on the role of prostate irradiation in newly-diagnosed patients with metastatic castration-sensitive prostate cancer (mCSPC).

Following the publication of the STAMPEDE trial, radiotherapy to the prostate bed in combination with ADT has become standard of care for patients with newly-diagnosed mCSPC and a low disease volume.¹ In an attempt to confirm the position of radiotherapy in these patients, the randomized phase III PEACE-1 trial randomized 1,172 patients with de novo mCSPC in a 2×2 design to receive standard of care (SoC) (ADT +/- docetaxel), SoC + abiraterone, SoC + radiotherapy or SoC+ abiraterone and radiotherapy.² With this design, PEACE-1 aimed at answering two questions: the role of abiraterone and the role of radiotherapy on top of standard of care (SoC).

Previous reports of this trial demonstrated that adding abiraterone to SoC was associated with a significantly better radiographic progression-free (rPFS) and overall survival (OS).² Surprisingly, however, updated results of PEACE-1 presented at ASCO 2023, failed to show a benefit in OS when radiotherapy was added, irrespective of the disease volume.³ In contrast, prostate irradiation added to SoC +/- abiraterone did lead to a significant improvement in the time to serious genitourinary events in the low-volume cohort, which was an argument for the authors to still recommend it in this setting.³

Both Prof Joniau and Prof Tombal were surprised by the lack of a survival effect with radiotherapy, forcing them to rethink the role of prostate irradiation in patients with newly-diagnosed mCSPC. However, they also underscored not to underestimate the significant effect on genitourinary complications that was seen with radiotherapy. These complications are common in metastatic prostate cancer patients and can have a serious impact on their quality of life. As such, Prof Joniau concluded that for him, radiotherapy is likely still the way to go in low-volume mCSPC patients, especially when they present with a large local tumor bulk.