Early versus Late Salvage Radiotherapy for Recurrent Prostate Cancer Following Radical Prostatectomy

Abstract:Purpose/Objective: An elevated PSA level after prostatectomy is the earliest indication of recurrent disease but the management strategy for these patients is controversial. Some physicians tend to observe these patients, while others recommend immediate salvage therapy. We retrospectively reviewed patients who underwent salvage external beam radiotherapy (RT) to the prostate bed for isolated PSA elevation or clinically apparent locally recurrent prostate cancer following radical prostatectomy (RP) to evaluate the outcome following salvage RT and identify prognostic factors. Materials/Methods: Between 1993 and 1999, 102 men with rising PSA levels presented for salvage RT following RP. Forty-two patients had a documented local recurrence (DLR), by digital rectal exam, and the remaining 60 had isolated PSA elevation (IPE) without clinically apparent local recurrence. All patients underwent RP between 1984 and 1996 and were pN0 at resection. The median time from RP to referral for RT was 2 years (range: 0.18 to 10 years). No one received androgen deprivation therapy prior to RT. All patients had a negative bone scan and CT of the abdomen and pelvis prior to RT. Patients were treated with 10 MV photons using a 4-field technique and custom blocks to a total dose of 41 to 70 Gy (median 66 Gy) in 1.8 to 2.0 Gy fractions. Median follow-up after RT was 4.3 years (range: 0.13 to 8.7 years). Biochemical disease-free survival (bDFS), was defined as maintaining a PSA of 64 Gy had significantly improved bDFS at 5 years compared to the other patients (69% vs. 28%, p = 0.02). Among the entire cohort, a significant difference in the rate of bDFS at 5 years was present-62%, 36%, and 15%-for pre-RT PSA levels 1.2 ng/mL, respectively (p = 0.008). A pre-RT PSA level > 0.69 ng/ml (p = 0.03, RR 1.95, CI 1.05 to 3.82), RT simulation without bowel and bladder contrast (p = 0.01, RR 3.58, CI 1.32 to 8.27), and Gleason score > 8 (p = 0.01, RR 1.39, CI 1.08 to 1.81) were independent predictors of biochemical failure following RT on multivariate analysis. Seven patients (7%) experienced chronic grade 3 or 4 RT-related toxicity. Conclusions: Early treatment with a sufficiently high dose of RT maximizes durable salvage in patients with recurrent disease following RP, conferring a significant improvement in biochemical disease free and cause-specific survival. The best outcome was seen in patients with a pre-salvage RT PSA level 8 or pre-RT PSA levels > 0.69 have poorer outcomes and may benefit from a combined approach with hormonal therapy plus RT. Because the benefit of salvage RT is greater with lower pre-salvage RT PSA levels, emphasis should be placed on earlier referral for salvage RT. Questions about this event email: orlan.macdonald@hsc.utah.edu

Q15-1332

Early versus Late Salvage Radiotherapy for Recurrent Prostate Cancer Following Radical Prostatectomy