Diagnostic Value of 18F Labelled PSMA PET/CT Imaging in Biochemical Recurrence of Prostate Cancer after Curative Therapy

Abstract Background Prostate cancer is the second most common malignancy and the fifth leading cause of cancer related mortality among men worldwide. Curatively intended treatment is directed for localized disease in form of radical prostatectomy and/or radiation therapy, However biochemical recurrence is encountered in about 15 to 53 % of treated patients within 10 years. Early detection of recurrence is crucial for directing curative salvage therapy. Aim of the Work Aim of the study is to evaluate the diagnostic performance of 18F-PSMA PET/CT imaging in biochemical recurrence of prostate cancer after radical prostatectomy, hormonal therapy and/or external beam. Patients and Methods This study is an exploratory cross-sectional study conducted at radiology department at Ain Shams University Hospitals. Our study included twenty six of previously treated prostate cancer patients referred with rising PSA level. The main source of data was the prospectively conducted 18 F PSMA PET/CT scans and clinical history of the patients referred to the nuclear imaging unit, Ain Shams University Hospitals for evaluation of possibility of disease recurrence. Results Twenty (76.9%) out of twenty six of included patients showed positive scan with at least one lesion suggestive of recurrent prostate carcinoma detected on 18F. PSMA-PET/CT with no positive scans detected at PSA level > 0.2 ng/ml. Participants were divided into three groups based on their PSA level distribution by the 25th and 75th percentiles. The first group included 6 patients representing the first quartile representing the bottom 25% of patients till the 25th percentile with PSA level >0.2). The second group included 14 patients representing the middle 50% with PSA level ranging from 0.2 to 4.5. The third group included 6 patients representing the top 25% from the 75th percentile with PSA level ≥ 4.5. There was a statistically significant very strong positive correlation between PSA level and number of recurrences in local region, regional Lymph nodes, distant Lymph nodes and viscera with p value (<0.001). However, there was no statistically significant correlation between PSA level and recurrence in Osseous regions with p vale (>0.05) Conclusion Our results confirmed the efficiency of 18F-PSMA-1007 PET/CT in detecting biochemical recurrence of prostate cancer at different PSA levels. The likelihood of a pathogenic 18F-PSMA PET/CT appears to be higher in patients with higher PSA levels, however the detection rate is still higher than other methods in patients at low PSA levels.