Introduction:

Focal therapy for PCa has evolved significantly over the past decade. One emerging modality is irreversible electroporation (IRE), which employs pulsed high-voltage, low-energy direct electric current to ablate tumors. Despite its potential, there remains a scarcity of data regarding oncologic outcomes including prostate specific antigen (PSA) response after treatment. In contemporary practice, surveillance strategies include imaging, repeat prostate biopsies and PSA response after treatment. The impact of PSA kinetics post-treatment on surveillance protocols is an active area of research in the field of focal therapy. We report our early experience with IRE and PSA kinetics post-treatment.

Methods:

We collected data on men who underwent IRE for PCa between January 1, 2021, and December 31. All men undergoing IRE for PCa were identified, and men undergoing IRE as a second focal therapy or in salvage settings were excluded. Patient information was gathered from medical records and entered into a database with predefined variables. Oncologic outcomes, including PSA levels, MRI findings and pathology were recorded and updated prospectively. Per our institutional post-treatment surveillance protocol, all patients underwent PSA every 3 months, MRI at 6 months and repeat prostate biopsy at 1 year after treatment.  Descriptive statistics were conducted, and Krushkal-Wallis was used for univariable analysis. We used SPSS Version 26 for the analysis, and GraphPad Prism Version 10.2.3 was used for graph generation.

Results:

A total of 45 patients were included in the study; baseline characteristics are summarized in Tables 1. All patients were diagnosed with Grade group (GG) 2 or 3 PCa at the time of treatment. The median follow-up was 12.2 months (IQR 4 - 20.4 months). PSA kinetics following IRE are illustrated in Figure 1, showing a significant drop in median PSA levels at 3 months, with subsequent stabilization. Those who underwent hemi-gland ablation had a larger PSA drop of 82% (PSA 8.3 to 1.46) compared to those who were treated with focal or quadrant ablation with a 46% drop (PSA 6.0 to 3.25, p = 0.04). We found no correlation between PSA drop and recurrence rates, however, our data is also not powered to do so; only 19 patients have undergone post-treatment biopsy to date.

Conclusion:

Focal prostate IRE is a novel, minimally invasive treatment option for PCa. PSA kinetics after IRE is not well understood and its utility in post-treatment surveillance is unclear. In our cohort, we observed a substantial initial PSA reduction at 3 months and subsequent stabilization for most patients. More importantly, we defined the difference in PSA drop between focal and hemi-gland ablation. This significant difference highlights need to consider the extent of treatment zone when assessing PSA kinetics post-IRE.

Funding: N/A