Editor’s Note: At the recent oncology conference, Dr. Amar Kishan, Radiation Oncologist at the University of California, Los Angeles (UCLA), presented Abstract 305, a highly anticipated individual patient data (IPD) meta-analysis addressing the optimal patient selection and duration for hormone therapy (HT) combined with post-operative radiotherapy (RT) in recurrent prostate cancer.01 Study Rationale and Robust IPD Methodology
While the addition of HT to definitive RT improves overall survival (OS) in prostate cancer, its absolute benefit in the post-operative setting remains less clear and is complicated by cardiovascular, metabolic, and quality-of-life toxicities. Through the MARCAP consortium, Dr. Kishan’s team conducted the POSIDON meta-analysis, encompassing IPD from 6 randomized trials (N=6,057) with a median follow-up of 9 years. The study evaluated RT with or without HT (short-term or long-term) to precisely define which patients truly benefit.
02 Overall Survival vs. Metastasis-Free Survival
The overall cohort analysis revealed that the addition of HT did not yield a statistically significant OS benefit (HR=0.87), providing a mere 0.7% absolute benefit at 10 years. While metastasis-free survival (MFS) demonstrated a statistically significant improvement (HR=0.79; absolute benefit 3.8%), the data failed to meet the strict statistical threshold required for MFS to act as a definitive surrogate for OS in this context.
03 Pre-RT PSA: The Critical Threshold for Precision Treatment
A pivotal highlight of the presentation was the interaction analysis between pre-RT PSA levels and treatment efficacy. Multivariate spline modeling revealed a significant interaction (p=0.03): the OS benefit of adding HT is strictly restricted to patients with a pre-RT PSA > 0.5. For patients presenting with a pre-RT PSA ≤ 0.5, concurrent HT provided no OS advantage, indicating an opportunity to spare these patients from systemic toxicity.
04 Treatment Duration: Short-Term Therapy is Sufficient
Addressing the optimal duration of treatment, the meta-analysis found no significant interaction between the duration of HT and survival outcomes. Dr. Kishan emphasized that for the vast majority of patients requiring HT, short-term administration (4–6 months) is entirely sufficient. Long-term HT only correlated with potential surrogacy for OS benefit in patients with exceptionally elevated pre-RT PSA levels (>1.6).
Conclusion & Future Perspectives
Dr. Kishan concluded that routine HT for all patients undergoing post-operative RT is not supported by current evidence. Clinicians should reserve HT for patients with a pre-RT PSA > 0.5, utilizing a short-term regimen. Moving forward, the integration of advanced molecular imaging (PSMA PET) and prognostic biomarkers (such as Decipher) from ongoing trials will further refine treatment individualization in recurrent prostate cancer.
