MP09-08: Predictive Value of LacdiNAc-Glycosylated Prostate Specific Antigen at 3 Months After Focal Therapy with High-Intensity Focused Ultrasound for Detection of Clinically Significant Prostate Cancer during Follow-Up: A Multi-Institutional Study
Introduction: LacdiNAc-glycosylated prostate specific antigen (LDN-PSA) is a PSA carrying a prostate cancer (PC)-associated disaccharide LacdiNAc (GalNAcß1?4GlcNAc) at the non-reducing terminal of N-glycan. The objective of this study was to evaluate the predictive value of LDN-PSA at 3 months after focal therapy with high-intensity focused ultrasound (HIFU) for the detection of clinically significant prostate cancer (csPC) during follow-up. Methods: From 2018 to 2019, patients whose serum PSA levels were = 20 ng/ml, and who had undergone focal therapy with HIFU based on magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion image-guided target biopsy and systematic biopsies, were included. LDN-PSA was measured via an automated two-step Wisteria Floribunda Agglutinin lectin–anti-PSA antibody sandwich immunoassay, using an extremely sensitive surface plasmon field-enhanced fluorescence spectrometry system. During follow-up, patients who had elevated PSA values after focal therapy, underwent MRI-TRUS fusion image-guided target and systematic biopsies. The predictive values of LDN-PSA at 3 months after treatment for the prediction of csPC detection in the biopsies were evaluated. Results: Fifty-five patients were included in the study. During median follow-up period of 30 months, 6 patients were diagnosed as pathological recurrences at median 24 months after treatment. Although there were no significant differences in the median PSA and median PSA density (PSAD), there were significant differences in median LDN-PSA (1.69×10-2 U/mL vs. 1.03×10-2 U/mL, P = 0.018) and median LDN-PSAD (1.06×10-4 U/mL/cc vs. 0.444×10-4 U/mL/cc, P = 0.002) at 3 months after the treatment between the patients with and without detected csPC during follow-up. Using the cut-off value of 0.907×10-4 U/mL/cc of LDN-PSAD, 83% of the patients (n=5) who were diagnosed with pathological recurrence at median 20 months after the treatment, were already predicted to develop this pathological recurrence at 3 months after treatment. Conclusions: LDN-PSAD at 3 months after focal therapy with HIFU has the potential to predict pathological recurrences during follow-up of these patients. The results could contribute to earlier timing of salvage treatment after focal therapy for csPC. SOURCE OF Funding: None.
