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Published on: March 6, 2018
Influence of Adverse Pathologic Features on Potential Benefit of Hormone Therapy Use with Postoperative Radiotherapy
Amar U Kishan1, Yilun Sun2, Christopher C Parker3
1Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA, USA.
Background And Objective:
A recent individual patient data (IPD) meta-analysis of randomized trials found a limited overall survival (OS) and metastasis-free survival (MFS) benefit to the addition of hormonal therapy (HT) to postoperative radiotherapy for prostate cancer in patients with pre-radiotherapy prostate-specific antigen (PSA) ≤0.5 ng/ml. We evaluated whether the OS and MFS benefits of adding HT might be significantly modified by an increasing count of adverse pathological features (adverse feature count [AFC]).
Methods:
We obtained IPD from five randomized phase 3 trials of postoperative radiotherapy ± HT. AFC was prospectively defined as the sum (0-4) of grade group 4-5 disease, seminal vesicle invasion, positive surgical margins, and extracapsular extension. Intention-to-treat one-stage meta-analytical models were used. We also evaluated the interaction of the benefit of HT with a restricted score comprising only GG4-5 and seminal vesicle invasion (range 0-2), as a pre-specified sensitivity analysis.
Key Findings And Limitations:
We included IPD from 4781 patients with a median follow-up of 9.1 yr. AFC was independently prognostic for OS and MFS. However, AFC did not significantly modify the OS benefit of HT (interaction hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.79-1.10; p = 0.4) or MFS benefit (interaction HR, 0.88; 95% CI, 0.77-1.01; p = 0.08). Results were similar when AFC was analyzed categorically and in high-risk subsets, and when the restricted AFC score was used.
Conclusions And Clinical Implications:
Overall, the data suggest that although adverse pathological features are prognostic, they do not appear predictive of HT benefit after postoperative radiotherapy, which is relevant for patients with a PSA ≤0.5 ng/ml before radiation.