• To investigate the significance of the percentage of positive biopsy cores (PPBCs) in predicting the biochemical
outcome in patients with clinically localised prostate cancer undergoing low-dose rate brachytherapy (LDRB).
• A total of 326 consecutive patients underwent LDRB between February 1997 and January 2007. The cohort consisted of
68.7%, 30.4% and 0.9% of low-, intermediate- and high-risk groups respectively as defined by the D'Amico classification.
Patients were stratified according to PPBCs (<35%, 35-50%, >50%).
• Of the 326 men, 316 (97%) met the study criteria and were included in the analysis. The median follow-up was 66.3
(12.9-147.5) months. Thirty-eight men (12%) developed evidence of biochemical relapse as defined by the Phoenix definition
at a median of 44.5 (4-133) months. The overall 5-year and 10-year biochemical relapse-free rate (BRFR) was
91.9% (95% CI 87.9% to 94.6%) and 76.9% (95% CI 66% to 84%) respectively.
• On univariate analysis, Gleason score (p=0.03), D'Amico risk groups (p=0.004) and PPBCs (p=0.001) were significant
predictors of biochemical failure. In the multivariate model, the PPBCs (p=0.0006) and pretreatment PSA (p=0.004) were
the only variables that predicted for biochemical failure. The 5-year biochemical relapse-free rate was 93.5%, 93.0% and
76.5% for the PPBCs <35%, 35%-50% and >50% respectively (p=0.001).
• The PPBC is an important independent predictor of the 5-year biochemical relapse-free survival after
LDRB. This finding suggests that patients with high volume tumour are at increased risk of biochemical failure with