Comparison of seed brachytherapy or external beam radiotherapy (70 Gy or 74 Gy) in 919 low-risk prostate cancer patients

Purpose The aim of this analysis was to compare the biochemical no evidence of disease (bNED) rates in low-risk prostate cancer patients treated at two centers of excellence using different approaches: seed brachytherapy (BT) and external beam radiotherapy (EBRT). Materials and methods A total of 919 low-risk prostate cancer patients, treated from 1998–2008, were identified in the two databases. In Utrecht, 667 patients received I-125 BT applying a dose of 144 Gy. In Vienna, 252 patients were treated with EBRT, applying a local dose of 70 Gy in 82 patients and 74 Gy in 170 patients. bNED rates (Phoenix definition) were assessed. Results The median follow-up was 46 months (range 1–148 months). The 5-year actuarial bNED rates were 94% for BT patients and 88% for EBRT patients (p = 0.002)—84% for patients receiving 70 Gy and 91% for patients receiving 74 Gy, respectively. In the univariate analysis, patients receiving 70 Gy showed significantly worse outcome compared to BT (p = 0.001) and a difference close to significance compared to 74 Gy (p = 0.06). In the multivariate analysis including tumor stage, Gleason score, initial PSA, hormonal therapy, and dose, patients receiving 70 Gy EBRT showed significantly worse bNED rates compared to BT patients. Conclusion Low-risk prostate cancer patients receiving 74 Gy by EBRT show comparable biochemical control rates to patients receiving seed brachytherapy, whereas patients receiving 70 Gy show significantly worse outcome.