Comparison between external beam radiotherapy (70 Gy/74 Gy) and permanent interstitial brachytherapy in 890 intermediate risk prostate cancer patients.

Purpose: Aim of this analysis was to compare biochemical no evidence of disease (bNED) rates in intermediate-risk prostate-cancer patients treated at two centres of excellence using different approaches: permanent interstitial brachytherapy (BT) and external beam radiotherapy (EBRT).

Materials And Methods: A total of 890 intermediate-risk prostate-cancer patients, who were treated from 1998 to 2008, were identified in the two local databases. In Utrecht 601 patients received I-125 BT applying a dose of 144 Gy. In Vienna 289 patients were treated by EBRT, applying a local dose of 70 Gy in 105 patients and 74 Gy in 184 patients. bNED-rates (Phoenix-definition) were assessed.

Results: Median follow-up was 48 months (1-150). 5-Year actuarial bNED-rates were 81% for BT-patients and 75% for EBRT-patients (67% for 70 Gy and 82% for 74 Gy), respectively. In univariate analysis no difference between BT and EBRT could be detected. In multivariate analysis including tumour-stage, GleasonScore, initial PSA, hormonal therapy and treatment-centre (BT vs. EBRT) only T-stage, GleasonScore and PSA were found to be significant. Additional analysis including radiation dose showed the same outcome.

Conclusions: Intermediate-risk prostate cancer patients treated by permanent interstitial brachytherapy show biochemical tumour-control-rates which are comparable to EBRT of 74 Gy.