Florastamin Uptake on PSMA PET/CT as an Imaging Biomarker of Tumor Aggressiveness in Prostate Cancer

Background: This study aimed to evaluate the association between the uptake on F-18 florastamin PET/CT targeting the prostate-specific membrane antigen expression, and the histopathological grade of the primary tumor in newly diagnosed prostate cancer patients. Methods: From the prospectively collected data set from a larger phase III multicenter trial of East Asian men with florastamin PET/CT performed under suspicion of prostate cancer based on elevated prostate-specific antigen (PSA) levels, this subset analysis reviewed data from a single institution of pathologically confirmed prostate cancer cases. The maximum standardized uptake value (SUVmax) was measured from the primary tumor on florastamin PET/CT images of 110 participants. The International Society of Urological Pathology (ISUP) grade following surgery or biopsy was classified as low-risk (ISUP 1), intermediate-risk (ISUP 2–3), or high-risk (ISUP 4–5). Correlation was between the SUVmax and the ISUP was tested. PSA level and Prostate Imaging Reporting and Data system (PIRADS) from MRI were also assessed for association with the ISUP grade. Results: A significant positive correlation was found between the SUVmax of the primary tumor in the prostate and the ISUP group (ρ = 0.541, p<0.001). A significant correlation was found between the PSA level and the ISUP grade group (ρ = 0.328, p=0.001), and between the SUVmax and PIRADS (ρ = 0.516, p<0.001). There was also a positive correlation between the PSA level and SUVmax as well (ρ = 0.379, p < 0.001). Conclusions: Our study demonstrated that the uptake values of the prostate tumor are associated with the ISUP grade groups in East Asian men with prostate cancer, and suggest SUVmax could be an imaging biomarker of tumor aggressiveness.