A randomised phase-III trial compared external beam radiotherapy (EBRT) alone with EBRT combined with high-dose-rate brachytherapy boost (HDR-BTb) in localised prostate adenocarcinoma.

From December 1997 to August 2005, 218 patients were assigned to EBRT alone (n=108) or EBRT followed by a temporary high-dose-rate implant (n=110). Patients were stratified according to tumour stage, PSA, Gleason score and androgen deprivation therapy (ADT). Biochemical/clinical relapse-free survival (RFS) was the primary endpoint. Secondary endpoints were overall survival (OS), urinary and bowel toxicity.

RFS was significantly higher in patients treated with EBRT+HDR-BTb (log rank p=0.04). In multivariate analysis treatment arm, risk category and ADT were significant covariates for risk of relapse. Differences in OS were not significant. Incidence of severe late urinary and bowel morbidity was similar.

EBRT+HDR-BTb resulted in a significant improvement in RFS compared to EBRT alone with a 31% reduction in the risk of recurrence (p=0.01) and similar incidence of severe late urinary and rectal morbidity.