Highlights
An individual patient data (IPD) meta-analysis of six randomized phase 3 trials, encompassing 6,057 patients, found that adding hormone therapy to postoperative radiotherapy (PORT) did not significantly improve overall survival (HR 0.87, p=0.06).
Pre-radiotherapy PSA levels were identified as a critical predictive biomarker; patients with a PSA of 0.5 ng/mL or less derived no meaningful survival benefit from either short-term or long-term hormone therapy.
The benefit of long-term hormone therapy (24 months) only reached statistical significance for overall survival when the pre-PORT PSA exceeded 1.6 ng/mL.
These findings challenge the routine use of androgen deprivation therapy in the early salvage setting, highlighting the need for personalized treatment strategies and molecular biomarkers.
Background: The Dilemma of Postoperative Recurrence
Prostate cancer remains one of the most common malignancies in men worldwide. While radical prostatectomy is a definitive and often curative treatment for localized disease, approximately 30% to 40% of patients will experience a biochemical recurrence, defined by a rising prostate-specific antigen (PSA) level. For these patients, postoperative radiotherapy (PORT), often referred to as salvage radiotherapy, is the standard of care to prevent further disease progression and metastasis.
The addition of hormone therapy, specifically androgen deprivation therapy (ADT), to definitive radiotherapy for localized prostate cancer has been shown to improve overall survival in multiple landmark trials. However, the evidence for adding ADT to PORT has been less clear. Previous trials, such as RTOG 9601 and GETUG-AFU 16, provided conflicting signals regarding the magnitude of benefit and the specific patient populations that gain the most from combined modality therapy. Clinicians have long debated whether all patients with recurrent disease require the systemic side effects of ADT—including cardiovascular risks, metabolic changes, and quality-of-life impairments—when undergoing salvage radiation.
Study Design and Methodology
To address this uncertainty, researchers conducted a comprehensive individual patient data (IPD) meta-analysis under the framework of the MARCAP (Meta-analysis of Randomized trials in Cancer of the Prostate) consortium. This approach is considered the gold standard for meta-analyses as it allows for more granular exploration of patient-level interactions than aggregate data meta-analyses.
The study identified randomized, phase 3 trials that compared PORT alone to PORT combined with hormone therapy. A systematic search of MEDLINE, Embase, Scopus, and trial registries was conducted through December 15, 2024. The primary outcome was overall survival (OS), with secondary outcomes including prostate cancer-specific mortality and progression-free survival.
The analysis included six trials: RTOG 9601, GETUG-AFU 16, RTOG 0534 (SPPORT), RADAR, SAKK 09/10, and TROG 08.03. In total, 6,057 patients were included with a median follow-up of 9.0 years. The researchers specifically evaluated the duration of hormone therapy, categorized as short-term (4-6 months) or long-term (24 months), and modeled the non-linear association between pre-PORT PSA levels and survival outcomes.
Key Findings: The Crucial Role of PSA Thresholds
Overall Survival Outcomes
The primary analysis revealed that adding hormone therapy to PORT did not result in a statistically significant improvement in overall survival for the total cohort. The hazard ratio (HR) was 0.87 (95% CI 0.76-1.01, p=0.06). While there was a trend toward benefit, it did not meet the threshold for clinical certainty across the unselected population.
The Impact of Pre-PORT PSA
The most striking finding of the study was the significant interaction between the pre-PORT PSA level and the efficacy of hormone therapy (p-interaction=0.02). For patients with a pre-PORT PSA of 0.5 ng/mL or less, there was no meaningful overall survival benefit regardless of whether hormone therapy was administered. This is a critical observation, as many modern guidelines advocate for early salvage radiotherapy when PSA levels are low (e.g., 0.2 to 0.5 ng/mL) to maximize the chances of local control.
Short-Term vs. Long-Term Hormone Therapy
The study also examined whether the duration of ADT mattered. For patients receiving short-term hormone therapy (n=3,938), the 95% confidence interval for the hazard ratio crossed 1.0 at all PSA levels, suggesting a lack of definitive survival benefit across the board for short courses of ADT in this context. In contrast, for patients receiving long-term hormone therapy (n=1,088), a significant survival benefit emerged, but only at higher PSA levels. Specifically, the upper bound of the 95% CI for the HR fell below 1.0 only when the pre-PORT PSA was greater than 1.6 ng/mL.
Expert Commentary and Clinical Implications
The results of this IPD meta-analysis, published in The Lancet, represent the most robust evidence to date regarding the use of ADT with PORT. The findings suggest a paradigm shift is necessary in how we approach biochemical recurrence. For years, the oncology community has leaned toward intensifying therapy by adding ADT to salvage radiation. However, these data suggest that for a substantial portion of patients—those with low PSA levels—this intensification adds toxicity without a demonstrable survival advantage.
One major consideration is the toxicity profile of ADT. Long-term androgen deprivation is associated with increased risks of bone fractures, diabetes, sarcopenia, and potentially cognitive decline. In an aging population of prostate cancer survivors, avoiding these side effects in patients who are unlikely to benefit is a significant win for patient-centered care and healthcare value.
However, the study also highlights a significant gap in our current diagnostic toolkit. While PSA is a useful marker, it is a surrogate for tumor burden rather than tumor biology. The researchers emphasize an “unmet need” for better biomarkers. Molecular signatures, such as the Decipher genomic classifier, may eventually prove more adept at identifying which low-PSA patients have aggressive biology that requires systemic intensification, and which can be safely treated with radiation alone.
Limitations and Considerations
While the IPD meta-analysis is rigorous, some limitations must be noted. The trials included spanned several decades, during which imaging technology evolved significantly. The advent of PSMA-PET (Prostate-Specific Membrane Antigen Positron Emission Tomography) has revolutionized the detection of recurrence, allowing for the identification of metastatic disease at very low PSA levels. The patients in the analyzed trials were largely staged with conventional imaging (CT and bone scans), which is less sensitive. Therefore, the results must be interpreted carefully in the context of modern PSMA-PET-guided salvage therapy.
Additionally, while overall survival is the hardest and most important endpoint, hormone therapy does improve biochemical control and reduces the risk of distant metastasis. For some patients, delaying the progression of disease is a valid clinical goal, even if a survival benefit is not immediately apparent at 10 years.
Conclusion
The MARCAP consortium’s analysis provides a clear message: the benefit of adding hormone therapy to postoperative radiotherapy is highly dependent on the patient’s PSA level at the time of recurrence. For those with a PSA of 0.5 ng/mL or less, the routine addition of ADT should be questioned, as it does not appear to improve overall survival. Conversely, for patients with higher PSA levels, particularly those above 1.6 ng/mL, long-term ADT remains a vital component of the treatment regimen. This study moves the field closer to a personalized medicine approach, where treatment intensity is titrated to individual risk rather than applied as a one-size-fits-all solution.
Funding and Registration
This study was funded by the National Institutes of Health (NIH). It was conducted under the master protocol of the MARCAP Consortium and is registered with PROSPERO (CRD42019134376).
References
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3. Carrie C, Hasbini A, de Laroche G, et al. Salvage radiotherapy with or without short-term hormone therapy for rising prostate-specific antigen concentration after radical prostatectomy (GETUG-AFU 16): a randomised, multicentre, open-label phase 3 trial. Lancet Oncol. 2016;17(6):747-756. doi:10.1016/S1470-2045(16)00111-X.
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