Background
Phase III RCT (SWOG 8794). 431 men with pT3N0M0 prostate cancer randomized after radical prostatectomy. Eligible patients had pathologic evidence of extraprostatic extension, seminal vesicle invasion, or positive surgical margins. Median follow-up ~12.5 years.
Interventions and follow up
Arm A: Adjuvant radiotherapy 60–64 Gy to the prostatic fossa, beginning within 18 weeks of prostatectomy
Arm B: Observation (no immediate radiotherapy)
Primary endpoint: Metastasis-free survival
mFollow up: 12.6 year
Arm B: Observation (no immediate radiotherapy)
Primary endpoint: Metastasis-free survival
mFollow up: 12.6 year
Results
Metastasis-free survival: Significantly improved with adjuvant RT (HR 0.71, 95% CI 0.54–0.94, P=.016)
OS: Significantly improved with adjuvant RT (HR 0.72, 95% CI 0.55–0.96, P=.023)
PSA relapse-free survival: HR 0.43, P<.001
OS: Significantly improved with adjuvant RT (HR 0.72, 95% CI 0.55–0.96, P=.023)
PSA relapse-free survival: HR 0.43, P<.001
Adverse events
Main adverse events: Grade 3 GI toxicity ~5% adjuvant RT arm. Grade 3 GU toxicity ~4% adjuvant RT arm. Urethral stricture higher in RT group. No grade 4 events reported.
Conclusions
Adjuvant radiotherapy after radical prostatectomy for pT3N0M0 prostate cancer significantly reduced the risk of metastasis and improved overall survival at long-term follow-up, supporting immediate postoperative irradiation in high-risk pT3 disease.
Key Limitations
Key Limitations: Enrolled from 1988–1997; PSA thresholds and surgical technique differ from modern practice. Observation arm allowed salvage RT at progression, complicating interpretation of OS benefit as attributable to adjuvant vs. early salvage RT. The OS benefit emerged only at long follow-up and was not pre-specified as primary. Adjuvant RT may overtreat patients cured by surgery alone.
Clinical Context
SWOG 8794, along with EORTC 22911 and ARO 96-02, established the biochemical and metastatic benefits of adjuvant RT for pT3 prostate cancer. The RAVES and RADICALS-RT trials subsequently demonstrated that early salvage RT (at PSA rise) achieves equivalent outcomes, shifting practice toward observation-then-salvage in most patients. SWOG 8794 is one of the few adjuvant RT trials showing OS benefit.
References