Impact of PSA Levels During Salvage Radiotherapy on Metastasis-Free Survival After Radical Prostatectomy

Overview

This study evaluated the effect of PSA levels at the initiation of salvage radiotherapy (sRT) on metastasis-free survival (MFS) in prostate cancer patients post-radical prostatectomy. Early sRT initiation at PSA < 0.5 ng/ml, particularly ≤ 0.25 ng/ml, was associated with improved MFS, especially in high-risk patients with adverse pathological features.

Background

Adjuvant radiotherapy (aRT) is recommended for prostate cancer patients with high-risk pathological features to reduce recurrence risk, but some patients decline due to side effects. Salvage radiotherapy (sRT) is advised upon biochemical recurrence (BCR), defined by rising PSA levels after radical prostatectomy, though no specific PSA threshold for sRT initiation is currently established. Prior studies suggest early sRT may improve oncological outcomes, but optimal timing and PSA cut-offs require further validation.

Data Highlights

Key Findings

• Early sRT initiation at PSA < 0.5 ng/ml was achieved in 69% of patients and associated with younger median age and lower tumor infiltration.
• Median PSA at sRT start was significantly lower in the early sRT group (0.24 ng/ml) compared to standard sRT (0.89 ng/ml).
• High-risk patients (pT3–4, Gleason 8–10, or pN1) comprised 61% of the cohort and were a focus for subgroup analyses.
• Kaplan-Meier analyses demonstrated improved metastasis-free survival in patients starting sRT at PSA < 0.5 ng/ml versus ≥ 0.5 ng/ml.
• A stricter PSA cut-off of ≤ 0.25 ng/ml further validated better MFS outcomes, supporting early intervention.
• Multivariable Cox regression adjusted for confounders confirmed PSA level at sRT initiation as an independent predictor of MFS.

Clinical Implications

Initiating salvage radiotherapy at lower PSA levels, ideally below 0.25 ng/ml, may improve metastasis-free survival in patients with biochemical recurrence after radical prostatectomy. This is particularly relevant for patients with high-risk pathological features, supporting early PSA monitoring and timely sRT initiation. Clinicians should consider PSA thresholds alongside other risk factors to optimize treatment timing.

Conclusion

Early salvage radiotherapy initiated at lower PSA levels is associated with improved metastasis-free survival post-radical prostatectomy, especially in high-risk patients. These findings support the clinical benefit of early intervention guided by PSA monitoring.

References

1. European Urology Association Guidelines 2024 -- Management of Prostate Cancer
2. Tilki et al. 2023 -- Effectiveness of Salvage Radiotherapy at PSA < 0.25 ng/ml
3. University Cancer Center Frankfurt (UCT) Database Study 2014-2024 -- Salvage Radiotherapy Outcomes