Ductal prostate cancer staging: Role of PSMA PET/CT.

Introduction: To evaluate the accuracy of PSMA PET/CT in the diagnosis and clinical staging of prostatic ductal adenocarcinoma (DAC).

Materials and methods: Two Caucasian men 58 and 62 years old were admitted to our Department for dysuria: the patients had not familiarity for prostate cancer (PCa), PSA values were 5.6 and 2.8 ng/ml, digital rectal examination was positive, multiparametric magnetic resonance image (mpMRI) showed for both the presence of an index lesion PIRADS score 5. The patients underwent extended transperineal prostate biopsy combined with four mpMRI/TRUS fusion biopsy under sedation and antibiotic prophylaxis; biopsy histology demonstrated the presence of a mixed PCa characterized by DAC and acinar PCa (Grade Group 4/Gleason score 8). The patients underwent clinical staging performing lung and abdominal CT, bone scan and fluoride 18 (18F) PSMA PET/CT.

Results: Conventional imaging was negative for distant metastases; 18F-PSMA PET/CT showed in both patients an intraprostatic lesion characterized by a standardized uptake value (SUVmax) equal to 4.6 and 4.9 in the absence of distant lesions suspicious for metastases. Following multidisciplinary evaluation, the patients underwent radical prostatectomy plus extended pelvic lymphadenectomy. Definitive specimen showed the presence in both cases of a mixed pT3bN1 PCa (ductal plus acinar pattern Grade Group 4) with positive surgical margins, neuronal invasion, and nodes metastases (5/20 and 6/24, respectively). Post-operative PSA in the two patients was 0.8 and 0.3 ng/ml, therefore patients underwent adjuvant therapy.

Conclusions: Conventional imaging and PSMA PET/CT could result inadequate in clinical staging of DAC, the use of more imaging data (i.e. mpMRI and/or F-18 FDG) could improve overall accuracy.