MP45-06: Clinical significance of &[alpha]2,3-sialylated prostate-specific antigen density and MRI for high-grade prostate cancer in biopsy-naïve men with elevated PSA level.

Tohru Yoneyama*, Shingo Hatakeyama, Mihoko Sutoh Yoneyama, Yuki Tobisawa, Takuma Narita, Hirotake Kodama, Masaki Momota, Hirosaki, Japan, Hiroyuki Ito, Aomori, Japan, Shintaro Narita, Akita, Japan, Fumiyasu Tsushima, Hirosaki, Japan, Koji Mitsuzuka, Sendai, Japan, Takahiro Yoneyama, Yasuhiro Hashimoto, Hirosaki, Japan, Wilhelmina Duivenvoorden, Jehonathan H. Pinthus, Hamilton, Canada, Shingo Kakeda, Hirosaki, Japan, Akihiro Ito, Sendai, Japan, Norihiko Tsuchiya, Yamagata, Japan, Tomonori Habuchi, Akita, Japan, Chikara Ohyama, Hirosaki, Japan

Introduction: To reduce unnecessary biopsies, biomarker discriminating high-grade prostate cancer (HGPC) greater than grade group 2 are needed.  The presence of a2,3-sialylated prostate-specific antigen (S2,3PSA) in sera with prostate cancer (PC) patients is a potential marker of their aggressiveness. The objective was to characterized the origin of S2,3PSA in prostate tissue, and studied the clinical performance of %S2,3PSA density (%S2,3PSAD) alone and in combination with MRI for the detection of high-grade PC (HGPC) in men with elevated PSA.

Methods: %S2,3PSA of benign and cancer tissue was measured in 71 radical prostatectomy specimens. The diagnostic performance of %S2,3PSA density (%S2,3PSAD) alone (primary outcome) and %S2,3PSAD combined with Prostate Imaging Reporting and Data System (PI-RADS) scores (secondary outcome) was evaluated by retrospective systematic biopsy cohort (n = 654) and prospective MRI-targeted biopsy cohort (n = 79) respectively, analyzed using ROC and DCA analysis.

Results: %S2,3PSA was significantly higher in Gleason pattern 4 and 5 tissues compared to benign prostate tissue. In the retrospective cohort, the AUC of %S2,3PSAD for detecting HGPC was superior to total PSA (tPSA) or PSA density (PSAD) (0.7704 vs. 0.5431 and 0.7140, all p  <0.001). In the prospective cohort, %S2,3PSAD was superior to tPSA, PSAD, and PI-RADS (AUC: 0.8194 vs. 0.5058, 0.7177 and 0.7661, all p  <0.05) and biopsy avoidance rate of %S2,3PSAD+PI-RADS+tPSA+digital rectal examination (DRE) was superior to PI-RADS+tPSA+DRE (24% vs. 13.9%) at 30% risk threshold.

Conclusions: The diagnostic performance of %S2,3PSAD was superior to conventional strategies but comparable to MRI.

Source of Funding: This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant nos. 15K15579 and 15H02563) and also supported by Sakurai Memorial Medical Research Foundation.