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. <b>Methods:</b> 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 (SUV_max) 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. <b>Results:</b> In 94.9% of patients, the index tumor was correctly identified with PET. SUV_max was significantly higher in the tumors vs normal prostate tissue, but no significant differences were found between different ISUP grades and SUV_max There was a poor correlation between PSA at diagnosis and SUV_max (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. <b>Conclusion:</b> 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.