Salvage brachytherapy for recurrent prostate cancer

Abstract

Purpose: To evaluate the role of salvage prostate brachytherapy for locally recurrent prostate cancer after external beam radiation alone.

Methods and materials: Sixty-nine consecutive patients treated with salvage brachytherapy after a local failure were analyzed. All patients were found to have pathologic proven recurrent prostate cancer at least 2 years after initial therapy and no regional or distant disease on imaging studies. Pd-103 was used with a prescribed pD90 of 100 Gy. In total, 89.9% of patients received androgen suppression (AS) as part of their salvage therapy. Patients whose prostate-specific antigen >5.0 ng/mL while on AS were considered to have castration resistant prostate cancer (CRPC). Patients on AS >6 months before salvage brachytherapy were considered to have delayed therapy. Patients retreated within 5 years after their initial treatment were considered to have early failures.

Results: Total median followup after salvage therapy was 5.0 years (0.6-13.7). From the date of salvage, 5-year biochemical control for low-risk patients was 85.6%, intermediate-risk patients 74.8%, and high-risk patients 66%. Five-year biochemical control was 73.8% for non-CRPC and 22% for CRPC cases (<0.001). Including and excluding CRPC cases, early treatment after failure vs. delayed treatment was significantly better (p<0.05). Chronic adverse events were seen in few patients, with genitourinary Grade 3 toxicity of 8.7% and no genitourinary Grade 4 or gastrointestinal Grade 3 or higher toxicities.

Conclusions: A subset of failures after definitive radiation is local in nature, and excellent control is possible with salvage brachytherapy.

Keywords: Androgen suppression; Biochemical control; Biochemical failure; Brachytherapy; Castration resistant; Local failure; Outcome; Prostate cancer; Radiation therapy; Salvage therapy.