Session Item

Prostate cancer is the most prevalent cancer among men worldwide, with its incidence rising with increasing age. Iodine brachytherapy (I-125 BT) is a known and validated treatment option for selected patients. Several studies investigated clinical, demographic, dosimetric and biochemical parameters related with disease control in patients treat with I-125 BT. The purpose of this study is to evaluate the outcome for low and intermediate risk prostate cancer following I-125 BT, specifically if prostate-specific antigen nadir (nPSA) is an independent predictor of disease-free survival (DFS), overall survival (OS) or disease specific survival (DSS).

In the period from January 2013 and October 2016, 250 patients were treated with I-125 BT alone. Patients were divided into three PSA nadir subgroups: group A <0. 2ng/mL; group B 0. 21 – 1 ng/mL; group C >1 ng/mL Biochemical recurrence was defined according to the Phoenix Consensus criteria... The impact of nPSA on DFS, OS and DSS was assessed using log rank test for univariate analysis and Cox regression for multivariate analysis. Statistical analysis was performed with SPSSv27 and considered statistically significant if p <0.05.

Median follow-up time was 79 months (39 – 105 months). Median nPSA was 0.5 ng/mL. A PSA nadir of ≤0.2 ng/ml, 0.21–1 ng/ml, and >1 ng/ml was reached by 81.2%, 16.8%, and 2% of patients, respectively. DFS at 5 years was 99.5%, 76.2% and 40%, respectively for the three groups (p<0.001). This relation of nPSA groups on DFS was confirmed in Cox multivariate analysis (p<0.001). There were no significant differences in OS or DSS for the three groups; neither in Log Rank (p=0.6; p=2.2 respectively) or Cox analysis (p=0.9; p=0.7 respectively.

This study demonstrated excellent control rates, DFS, and DSS of I-125 BT monotherapy, confirming its role as an effective treatment for selected cases. In our study, levels of nPSA after brachytherapy predicted long-term biochemical control both in univariate and multivariate analysis, namely increased control for nPSA values <0.2 ng/mL, and higher risk of recurrence for nPSA >1 ng/mL. A favourable outcome should be expected in patients that achieve PSA nadir levels of 0.2ng/mL or less.