Adding Radium to a Standard Prostate Cancer Pill Extended Men’s Survival

CATEGORY: MEN’S HEALTH

Six injections of a bone-seeking radioactive drug, added to a standard daily pill, helped men with advanced prostate cancer live longer. In the final count from a 446-man international trial, half the men on the combination were still alive beyond 38.2 months, compared with 32.6 months on the pill alone. That works out to a 24% lower risk of death over the study period.¹ The pill was enzalutamide, a hormone-blocking drug that starves prostate cancer of the testosterone signal it feeds on. The injections were radium-223, and the pairing isn’t approved yet.

A Radioactive Element That Behaves Like Calcium

Radium-223 has been an approved prostate cancer treatment on its own since 2013. Its trick is chemistry. The body handles radium much as it handles calcium, so the drug travels straight to spots where bone is being built and torn down. Those spots are exactly where prostate cancer tends to settle. Once there, it releases radiation that reaches only a few cell-widths, hitting tumor deposits in bone while mostly sparing everything else. The PEACE-3 trial asked whether sending it in early, alongside enzalutamide, beats the pill alone.²

Men Whose Cancer Had Reached Bone but Caused Little Pain

The trial enrolled 446 men whose cancer no longer responded to standard hormone-lowering treatment and had spread to at least two places in their bones. None had received chemotherapy for this stage, and none had more than mild pain. A computer draw, not their doctors, decided who got the add-on. Half took enzalutamide alone. The other half added six monthly radium injections. On the trial’s main measure, the time until scans showed the cancer growing, the combination held the disease in check for a median of 19.4 months versus 16.4 months.² The survival difference emerged over far longer watching: the final analysis arrived after a median follow-up of nearly five years.¹

Fractures Nearly Tripled Until Bone Protection Became Mandatory

The combination carried a cost, and the trial’s history shows how it was tamed. Early on, when bone-protecting medicines were optional, 54% of men on the combination broke a bone, against 20% on the pill alone. In 2018 the trial made continuous treatment with zoledronic acid or denosumab, drugs that slow bone breakdown, mandatory for everyone. After that, fracture rates fell to 14% with the combination and 11% without it.² The caution wasn’t theoretical. An earlier trial that paired radium-223 with a different hormone pill, abiraterone, was stopped after men on the combination suffered more fractures without living longer.³ Severe side effects overall were more common with the combination, 66% versus 56%, with high blood pressure the most frequent in both groups.

A Result the Trial Was Built to Find, and a Wait for Regulators

The investigators designed PEACE-3 to detect roughly a 32% slowing of disease progression, and that’s close to what they got. What they could not have scheduled was patience: the study took more than eight years to deliver its answer. The combination is not yet approved anywhere, though the manufacturer says it will take these results to regulators. The finding applies to a specific situation: cancer resistant to hormone therapy, spread to bone but not causing much pain, before chemotherapy. For men in that window, an old drug used earlier, with bone protection alongside, added months of life.

Key Takeaways

• Adding six monthly radium-223 injections to enzalutamide extended median survival from 32.6 to 38.2 months in men with hormone-resistant prostate cancer that had spread to bone, a 24% lower risk of death.
• Fractures were the main hazard. Mandatory bone-protecting medicine cut the combination’s fracture rate from 54% to 14%.
• Both drugs are individually approved, but the combination isn’t yet. The results come from men with bone-only spread, little pain, and no prior chemotherapy for this stage.
• An earlier trial pairing radium with a different hormone pill showed harm without benefit, so the gain appears specific to this pairing and to diligent bone protection.

References

1. Gillessen S, Gallardo E, Choudhury A, et al. Final overall survival results from EORTC 1333/PEACE-3 trial of enzalutamide plus radium-223 in metastatic castration-resistant prostate cancer. Annals of Oncology. 2026;37(5):736–742. link
2. Tombal B, Rodriguez-Vida A, Gillessen S, et al. Enzalutamide plus radium-223 in metastatic castration-resistant prostate cancer: results of the EORTC 1333/PEACE-3 trial. Annals of Oncology. 2025;36(9):1058–1067. link
3. Smith M, Parker C, Saad F, et al. Addition of radium-223 to abiraterone acetate and prednisone or prednisolone in patients with castration-resistant prostate cancer and bone metastases (ERA 223): a randomised, double-blind, placebo-controlled, phase 3 trial. The Lancet Oncology. 2019;20(3):408–419. link