RT Journal Article SR Electronic T1 The Use of FDG-PET in conjunction with PSMA-PET in Prostate Cancer JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP P1083 OP P1083 VO 64 IS supplement 1 A1 Gokhale, Saket A1 Kuang, Angie A1 Teichner, Eric A1 Subtirelu, Robert A1 Werner, Thomas A1 Høilund-Carlsen, Poul Flemming A1 Revheim, Mona-Elisabeth A1 Alavi, Abass A1 Raynor, William YR 2023 UL http://jnm.snmjournals.org/content/64/supplement_1/P1083.abstract AB P1083 Introduction: 1. Evaluate the effectiveness of prostate-specific membrane antigen (PSMA) PET in assessing prostate cancer in comparison to previously used tracers. 2. Discuss the utility of 18F-fluorodeoxyglucose (FDG)-PET in conjunction with PSMA-PET in assessing aggressive forms of prostate cancer.Methods: To identify relevant studies, a comprehensive search of the PubMed, Cochrane Library, and EMBASE databases was conducted; keywords related to PSMA PET scans, FDG PET, prostate cancer, and radiotracers were utilized. Our search intended to capture all original research studies that evaluated the effectiveness of FDG in conjunction with PSMA PET scans in the assessment of prostate cancer. Two reviewers independently screened the titles and abstracts of the identified studies. Discrepancies were resolved through discussion and deliberation. Findings were then synthesized in order to address the aforementioned objectives.Results: Prostate cancer (PCa) is one of the most frequently occurring malignancies and a leading cause of cancer death in men. PCa has previously been evaluated with tracers, such as 18F-sodium fluoride (NaF), choline, and fluciclovine. Most recently, PSMA has been introduced as the best overall option for PCa characterization. PSMA is a transmembrane protein with glutamate-carboxypeptidase activity. Prostatic cancer cells highly express this antigen while normal tissues have lower expression. Studies revealed that PSMA PET allows for the early identification of metastases at lower PSA levels compared to other imaging modalities. Radiopharmaceuticals can be developed to target PSMA due to the discrepancy in expression levels between PCa cells and normal cells. In addition to its high sensitivity and specificity in detecting disease, it has been shown to have a promising safety profile, further supporting widespread use in PCa staging and treatment management. Although FDG-PET does not present much utility in patients with low grade PCa, FDG-PET can provide useful information in conjunction with PSMA-PET in patients with more aggressive forms of the disease, such as castration-resistant prostate cancer (CRPC).CRPC is a form of PCa capable of growing even with low levels of testosterone. In aggressive PCa, especially forms with a Gleason score greater than 7, FDG-PET has shown success in the diagnosis and staging of tumors. Many CRPC patients are resistant to chemotherapy and therefore exhibit elevated FDG uptake. FDG-PET may show promise in evaluating response to treatments, such as enzalutamide and cabazitaxel) in CRPC patients. Studies have shown that in patients undergoing androgen deprivation therapy (ADT), patients exhibited reduced PSMA uptake as a result of the therapy, leading to an inaccurate assessment of the true disease state. This reduced level of PSMA was found to be due to the upregulation of glucose transporter 1, which is associated with increased FDG uptake. Furthermore, FDG-PET in conjunction with PSMA-PET shows higher metastases detection points compared to PSMA-PET alone. These findings show promise in the use of FDG-PET concurrently with PSMA-PET in the diagnosis of CRPC patients. PSMA radionuclide therapy only targets PCa cells that express PSMA. Therefore, FDG-PET is essential for identifying non-PSMA-avid tumors. Discordant disease visualized by FDG but not PSMA can therefore be used to exclude patients from PSMA therapy who are unlikely to benefit due to the presence of undifferentiated tumor cells.Conclusions: Several different PET tracers have historically been implicated in the staging of PCa, including NaF, choline, and fluciclovine among others. Recently, PSMA has been introduced as playing a major role in this domain, providing highly accurate diagnostic information with the additional advantage of theranostic applications. Concurrent use of FDG-PET along with PSMA-PET has shown great promise in the evaluation of disease in CRPC patients.