Introduction & Objectives
Systematic transrectal ultrasound (TRUS)-guided biopsies, performed for high serum prostate-specific antigen (PSA) levels, have limited accuracy in identifying primary prostate cancer (PCa). Our aim was to evaluate the accuracy of gallium-68 [68Ga] or fluorum-18 [18F] and prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) for the detection of primary Pca.
Materials & Methods
We retrospectively analyzed our prospectively maintained database, looking for all the patients with suspected PCa underwent both PSMA PET/CT and multiparametric magnetic resonance (mpMRI) prior to prostate biopsy. Both clinical and radiological variables have been collected, including among the first PSA, PSA density, and digital rectal examination (DRE), while PiRADS, PSMA-Rads, Suv max among the last. All these variables were compared in patients with a bioptic diagnosis positive or negative for PCa, using t-test to assess significant differences. Diagnostic performance of PSMA PET/CT for the detection of PCa was evaluated and compared with the diagnostic performance of mpMRI. The standard of reference was 12-core TRUS-guided biopsy.
Results
From January 2023 to September 2023, 53 patients were included in the study. The mean (+SD) age of the cohort was 69.4 years (+7.6), mean PSA level was 15.4 ng/ml (+15.6), with a mean PSA density of 0.30 ng/ml^2 (+0.38), and a mean prostate volume of 60.9 cc (+32.05). Fifteen (28%) patients were diagnosed with benign histology, while 38 (72%) were found to harbor PCa. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PSMA PET/CT for detecting PCa, evaluated using the prostate cancer molecular imaging standardized evaluation (PROMISE), was 97%, 43%, 82%, 86%, and 83%, respectively. Mean prostate maximum standardized uptake value (SUVmax) was significantly higher in PCa if compared to benign histology (8.7 ± 4.6 vs. 3.7 ± 1.7, p=0.002), in patients with PSA >20 ng/ml versus PSA <20 ng/ml (10.5 ± 6.6 vs. 6.7 ± 3.5, p 0.016), and in patients with Gleason's score (GS) score >7 versus GS ≤7 (14.8 ± 4.5 vs. 7.6 ± 2.4, p <0.001). SUVmax cutoff value of 5.4 on PSMA PET/CT showed a sensitivity of 78.4% and specificity of 90% (area under the curve 0.90).
Conclusions
PSMA PET/CT demonstrates precision and accuracy in distinguishing between benign histologies and PCa. Potentially, it can have a role in the preoperative workup that lead the patient undergo first prostate biopsy, increasing the information given by the mpMRI.
