Serum PSA evaluations during salvage radiotherapy for post-prostatectomy biochemical failures as prognosticators for treatment outcomes.
BACKGROUND
Serum prostate specific antigen (PSA) levels have proved to be sensitive markers for the diagnosis of prostate cancer. In addition, PSA levels are useful for detecting and monitoring prostate cancer progression after radiotherapy. Serum PSA evaluations during radiotherapy, however, have not been well documented. In this study, we investigate the prognostic value of PSA evaluations during salvage radiotherapy for prostatectomy failures.


METHODS
Forty-one patients with biochemical failures after prostatectomy treated with salvage radiotherapy consented to have their serum PSA levels evaluated at 30 Gy and 45 Gy of irradiation. All 41 patients had negative metastatic workup and pathologically uninvolved pelvic lymph nodes at the time of referral for salvage radiotherapy. Radiation therapy was delivered with 10--25 MV photons, with doses of 59.4--66.6 Gy. No patients received hormonal ablation therapy before irradiation.


RESULTS
The mean follow-up for all patients was 30.9 months. At last follow-up, 28/41 patients (68.3%) were free from biochemical failure, with 20 of 41 patients (48.8%) expressing undetectable PSA levels. Serum PSA evaluations at 30 Gy did not significantly predict for either biochemical (p = 0.0917) or clinical (p = 0.106) disease-free outcome. However, serum PSA evaluations at 45 Gy significantly predicted for both biochemical (p = 0.0043) and clinical (p = 0.0244) disease-free outcomes, with PSA elevations at 45 Gy significantly associated with poor outcomes. On univariate analysis of prognosticators for biochemical failures, the following were significant: an elevation in serum PSA levels at 45 Gy, detectable serum PSA immediately after prostatectomy, Gleason score 7--10, and serum PSA level >1 ng/ml before salvage radiotherapy.


CONCLUSIONS
Evaluation of serum PSA level at 45 Gy of salvage radiotherapy for biochemical relapses after prostatectomy may serve as a significant prognosticator for both biochemical and clinical disease-free outcomes.
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Department of Radiation Oncology, UCLA Medical Center, Los Angeles, CA, USA.
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Parker
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Kagan
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D000230:Adenocarcinoma / Q000097:blood / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D014408:Biomarkers, Tumor / Q000097:blood*; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005500:Follow-Up Studies; D006801:Humans; D015993:Life Tables; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D009363:Neoplasm Proteins / Q000097:blood*; D011237:Predictive Value of Tests; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011882:Radiotherapy, High-Energy; D012189:Retrospective Studies; D016879:Salvage Therapy; D016019:Survival Analysis; D017211:Treatment Failure; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D017430:Prostate-Specific Antigen