Tumor detection of 18F-PSMA-1007 in the prostate gland in patients with prostate cancer using prostatectomy specimens as reference method.

Abstract

Prostate-specific membrane antigen (PSMA) radiopharmaceuticals used with positron emission tomography/computed tomography (PET-CT) are a promising tool for managing patients with prostate cancer. This study aimed to determine the accuracy of 18F-PSMA-1007 PET-CT for detecting tumors in the prostate gland using radical prostatectomy (RP) specimens as a reference method and to determine whether a correlation exists between 18F-PSMA-1007 uptake and the International Society of Urological Pathology (ISUP) grade and prostate specific antigen (PSA) levels at diagnosis. Methods: Thirty-nine patients referred for 18F-PSMA-1007 PET-CT for initial staging and who underwent RP within four months were retrospectively included. Uptake of 18F-PSMA-1007 indicative of cancer was assessed and maximum standardized uptake values (SUVmax) and total lesion uptake (TLU) were calculated for the index tumor. Histopathology was assessed from RP specimens. True positive, false negative, and false positive lesions were calculated. Results: In 94.9% of patients, the index tumor was correctly identified with PET. SUVmax was significantly higher in the tumors vs normal prostate tissue, but no significant differences were found between different ISUP grades and SUVmax There was a poor correlation between PSA at diagnosis and SUVmax (r=0.23) and moderate agreement between PSA at diagnosis and TLU (r=0.67). When all tumors (also non-index tumors) were considered, many small tumors (approx. 1-2 mm) were not detected with PET. Conclusion: 18F-PSMA-1007 PET-CT performs well in correctly identifying the index tumor in patients with intermediate to high-risk prostate cancer. Approximately 5% of the index tumors were missed by PET, which agrees with previous studies.