Adding Hormone Suppression to Radiotherapy for Recurrent Prostate Cancer: For Whom and for How Long?
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Is adding hormone therapy to postoperative radiotherapy always necessary? Science is pursuing a single molecule circulating in the blood: the PSA threshold.
For patients with recurrence or a high risk after prostate cancer surgery (radical prostatectomy), postoperative radiotherapy (PORT) is a critical stop on the journey toward recovery. Yet a major dilemma has persisted for years: should we add hormone therapy (ADT), and if so, how long should it continue? Given the effects of hormone therapy on quality of life—hot flashes, fatigue, and metabolic changes—the era of a “standard approach for everyone” is coming to an end. The POSEIDON study offers precise guidance shaped by each patient’s own biological data.
The Power of Individual Data: The POSEIDON and MARCAP Collaboration
POSEIDON is a large meta-analysis of individual data from more than 5000 patients in 6 different Phase 3 randomized clinical trials. Study lead Dr. Amar U. Kishan (UCLA) emphasizes that the strength of this analysis lies not only in aggregate numbers, but in the depth of patients’ biological details—its granularity.
The research sifted through data from patients receiving postoperative radiotherapy who were followed for a median of 9 years, seeking answers to two fundamental questions: who needs hormone therapy after surgery, and how long should it last?
The PSA 0.5 Threshold: New Navigation in Hormone Therapy
The most striking finding of POSEIDON is that hormone therapy does not have the same effect on survival in every patient. Although the analyses show that adding hormones does not provide a survival benefit in the overall patient population, the picture changes completely at a particular biological threshold.
Only patients whose PSA is above this threshold obtain a significant benefit from hormone therapy.
In this group, adding hormones to radiotherapy does not improve survival. Continuing with radiotherapy alone is a wise choice that protects the patient from unnecessary side effects.
Hormone therapy improves overall survival in this group. However, a short course of 4-6 months is sufficient for this improvement; prolonged treatment for 24 months provides no additional contribution.
A Biological Reflection: The PSA Threshold and PET Imaging
Commenting on the study, Dr. Bridget F. Koontz notes that the PSA threshold of 0.5 is not coincidental, but aligns perfectly with modern imaging methods. Interestingly, a PSA level above 0.5 is the point at which a positive finding on PSMA PET—lymph node or distant involvement—is most likely.
In conclusion, the earlier prostate cancer recurrence is detected, at a low PSA level, the more successful radiotherapy alone is and the less hormone therapy is needed. This is one of the clearest examples of the “less but better” philosophy in oncology.
An Era of Precise Healing in Oncology
Our greatest aim on the journey with cancer is to offer patients healing while compromising their quality of life as little as possible. POSEIDON whispers this message: we no longer draw our swords at every possibility of recurrence; instead, we look to a single number circulating in the blood, the PSA compass.
The PSA 0.5 threshold is becoming the strongest discriminator in physicians’ hands. In light of this information, we can protect patients with early-detected recurrences from the exhausting effects of hormone therapy. Even when treatment is necessary, knowing that a short course of just 4-6 months is sufficient demonstrates that oncology is entering a more compassionate and precise phase. Healing means identifying the problem correctly and intervening only as much as needed.
Scientific References
- 1. Kishan AU, et al. Adding Hormone Therapy to Postoperative Radiotherapy in Prostate Cancer: POSEIDON Meta-analysis. ASCO GU 2026 Symposium (Abstract 305).
- 2. Kishan AU, Sun Y, Tree AC, et al. Hypofractionated radiotherapy for prostate cancer (HYDRA): an individual patient data meta-analysis. Lancet Oncol. 2025;26(4):459-469.
- 3. MARCAP Consortium: Meta-Analysis of Randomized trials in Cancer of the Prostate Data Insights.
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