Predictors of biochemical outcome with salvage conformal radiotherapy after radical prostatectomy for prostate cancer.

Abstract

To identify predictors of biochemical outcome following radiotherapy in patients with a rising prostate-specific antigen (PSA) after radical prostatectomy for prostate cancer. One hundred fifteen patients with a rising PSA after radical prostatectomy received salvage three-dimensional conformal radiotherapy (3D-CRT) alone or with neoadjuvant androgen deprivation. Tumor-related and treatment-related factors were evaluated to identify predictors of subsequent PSA failure. The median follow-up time after 3D-CRT was 42 months. The 4-year actuarial PSA relapse-free survival, distant metastasis-free survival, and overall survival rates were 46%, 83%, and 95%, respectively. Multivariate analysis, which was limited to 70 patients receiving radiation without androgen deprivation therapy, showed that negative/close margins (P =.03), absence of extracapsular extension (P <.01), and presence of seminal vesicle invasion (P <.01) were independent predictors of PSA relapse after radiotherapy. Neoadjuvant androgen deprivation did not improve the 4-year PSA relapse-free survival in patients with positive margins, extracapsular extension, and no seminal vesicle invasion (P =.24). However, neoadjuvant androgen deprivation did improve PSA relapse-free survival when one or more of these variables were absent (P =.03). Salvage 3D-CRT can provide biochemical control in selected patients with a rising PSA after radical prostatectomy. Among patients with positive margins and no poor prognostic features, 77% achieved PSA control after salvage 3D-CRT. Salvage neoadjuvant androgen deprivation therapy may improve short-term biochemical control, but it requires further study.