Salvage radiotherapy for biochemical failure after radical prostatectomy works best when the preradiotherapy PSA <0.6 ng/mL, long PSADT >10 months, positive margins, no seminal vesicle invasion and Gleason 4-7
Of all the men who develop biochemical recurrence after radical prostatectomy, 65% will develop bony metastases within 10 years if no salvage treatment is given – the key is to identify who this 65% will be. Also salvage radiotherapy will not work for patients who already have occult micro-metastatic disease beyond the pelvis. This landmark study followed 501 men who had a rising and detectable PSA after radical prostatectomy for prostate cancer and were all given salvage radiotherapy, over 45 months median follow up. Prior to receiving salvage radiotherapy, nearly all patients had a PSA >0.2 ng/mL, 21% had biopsy proven local recurrence, 17% received 3 months hormonal therapy and the dose was 65 Gy to the prostatic fossa. A complete response was a PSA ≤0.1 ng/mL, and disease progression was a rise in PSA >0.1 ng/mL above the post radiotherapy nadir. The key results were:
- The median preradiotherapy PSA was 0.72 ng/mL
- 67% achieved an initial complete response
- Over 45 months 50% developed disease progression
- The median time to progression was 12.5 months, with 92% having progressed within 4 years
- The 7 year disease-specific survival was 90%
- The 7 year overall survival was 82%.
The variables that predicted which patients would not have a durable response were:
- Gleason score 8-10
- Preradiotherapy PSA > 2.0 ng/mL
- Negative surgical margins
- PSADT ≤10 months
- Seminal vesicle invasion.
In summary try to treat these patients when the PSA is as low as possible, and well under PSA <0.6 ng/mL. Those who do best have PSA <0.6 ng/mL, positive margins, no seminal vesicle invasion, a long PSADT > 10 months and Gleason 4-7.