Tetreault–Laflamme A, et al. – This study was undertaken to investigate long term PSA stability after low dose rate prostate brachytherapy and predictors of biochemical failure when the PSA is slowly rising below the nadir + 2 ng/ml threshold. The results pf this study indicate that brachytherapy is highly curative with 86% of patients having a stable PSA at a surgical ablation level. Rising PSA is rare (6%) and often innocuous.

Methods

• 2339 low/ intermediate risk prostate cancers had Iodine-125 brachytherapy with a minimum 3 year follow between1998-2010.
• In this study, 49.7% had 6 months’ androgen deprivation.
• They retrieved clinical, dosimetric and PSA data from a prospective database .
• They categorized biochemical results as stable PSA, rising PSA (≥ 0.2ng/mL and increased ≥0.1ng/mL over preceding 2 years) or biochemical failure (defined as nadir+2).
• In this multivariate analysis, researchers distinguished predictors of failure used to create logistic regression models.

Results

• They found that 86% (n=2004) had stable PSA (nadir 0.03; PSA 60-months: 0.04 ng/ml), 6% (n=145) had rising PSA (nadir 0.16; PSA-60: 0.29) and 8% (n=190) had biochemical failure(nadir 0.51; p<0.001) at a median follow-up 89 months(37-199).
• Whether no prior ADT, PSA nadir (OR: 20.6 p<0.0001) and PSA-60 (OR: 18.3 p<0.0001) were the strongest predictors of failure.
• The logistic regression model (sensitivity:85%, specificity:98%) predicted failure in 9.8% (8/82).
• A second model created for the ADT-rising-PSA group applying predictive factors PSA-60 (OR: 53.9 p<0.0001) and T-stage (OR: 0.25 p=0.0008), predicted biochemical failure 54% (30/56) [sensitivity:85%, specificity:93%].
• In addition, the two predictive models yield an anticipated cure rate for the entire cohort of 90%.