Outcomes of Primary Lymph Node Staging of Intermediate and High Risk Prostate Cancer with 68Ga-PSMA Positron Emission Tomography/Computerized Tomography Compared to Histological Correlation of Pelvic Lymph Node Pathology.

PURPOSE: The majority of men who undergo pelvic lymph node dissection at radical prostatectomy have benign lymph node histology. The aim of this study was to assess the predictive value of preoperative 68Ga-PSMA (prostate specific membrane antigen) positron emission tomography/computerized tomography to predict histological metastasis on pelvic lymph node dissection performed during radical prostatectomy. MATERIALS AND METHODS: We retrospectively reviewed the sensitivity, specificity, and positive and negative predictive values of preoperative staging 68Ga-PSMA positron emission tomography/computerized tomography to identify histological lymph node metastasis in 208 consecutive men who subsequently proceeded with pelvic lymph node dissection at radical prostatectomy. RESULTS: Median prostate specific antigen was 7.6 µg/l, the lymph node count was 13 and Gleason score was 4 + 5. On a per patient basis only 21 of the 55 men with metastasis on histological examination were identified on 68Ga-PSMA positron emission tomography/computerized tomography for 38.2% sensitivity. Of the 143 men with no lymph node metastasis on 68Ga-PSMA imaging 34 had metastasis on histology for 80.8% negative predictive value. Specificity was 93.5% and positive predictive value was 67.7%. For the 172 histologically identified malignant lymph node metastases the sensitivity per node was 24.4% and specificity was 99.5%. CONCLUSIONS: If negative 68Ga-PSMA positron emission tomography/computerized tomography is used as the basis of not performing pelvic lymph node dissection, 80% of men would avoid unnecessary pelvic lymph node dissection. However, 68Ga-PSMA positron emission tomography/computerized tomography has poor sensitivity per node to detect all histologically positive lymph node metastases. Thus, pelvic lymph node dissection remains the gold standard to stage pelvic lymph nodes despite its known limitations and complications.

Risk of metastatic disease on 68 gallium-prostate-specific membrane antigen positron emission tomography/computed tomography scan for primary staging of 1253 men at the diagnosis of prostate cancer.

OBJECTIVE: To determine the number of men with 68 gallium-prostate-specific membrane antigen positron emission tomography/computed tomography (68 Ga-PSMA PET/CT) avid metastasis at diagnosis, as most data on 68 Ga-PSMA PET/CT are for the evaluation of recurrent disease after primary treatment and to our knowledge this study is the largest series of primary prostate cancer staging with 68 Ga-PSMA PET/CT. PATIENTS AND METHODS: A retrospective review conducted on 1253 consecutive men referred by urologists or radiation oncologists to our tertiary referral centre for 68 Ga-PSMA PET/CT scan for staging at the initial diagnosis of prostate cancer between July 2014 and June 2018. The primary outcome measure was to determine the risk of metastasis based on 68 Ga-PSMA PET/CT. Patients were risk stratified based on histological biopsy International Society of Urological Pathology (ISUP) grade, prostate-specific antigen (PSA) level, and staging with pre-biopsy multiparametric magnetic resonance imaging (mpMRI). Univariate and multivariate logistic regression were used to analyse results. RESULTS: The median PSA level was 6.5 ng/mL and median ISUP grade was 3, with high-risk disease in 49.7%. The prostate primary was PSMA avid in 91.7% of men. Metastatic disease was identified in 12.1% of men, including 8.2% with a PSA level of <10 ng/mL and 43% with a PSA level of >20 ng/mL. Metastases were identified in 6.4% with ISUP grade 2-3 and 21% with ISUP grade 4-5. Pre-biopsy mpMRI identified metastasis in 8.1% of T2 disease, increasing to 42.4% of T3b. Lymph node metastases were suspected in 107 men, with 47.7% outside the boundaries of an extended pelvic lymph node dissection. Skeletal metastases were identified in 4.7%. In men with intermediate-risk prostate cancer, metastases were identified in 5.2%, compared to 19.9% with high-risk disease. CONCLUSIONS: These results support the use of 68 Ga-PSMA PET/CT for primary staging of prostate cancer. Increasing PSA level, ISUP grade and radiological staging with mpMRI were all statistically significant prognostic factors for metastasis on both univariate and multivariate analysis.

Comparison between target magnetic resonance imaging (MRI) in-gantry and cognitively directed transperineal or transrectal-guided prostate biopsies for Prostate Imaging-Reporting and Data System (PI-RADS) 3-5 MRI lesions.

OBJECTIVE: To compare the detection rates of prostate cancer (PCa) in men with Prostate Imaging-Reporting and Data System (PI-RADS) 3-5 abnormalities on 3-Tesla multiparametric (mp) magnetic resonance imaging (MRI) using in-bore MRI-guided biopsy compared with cognitively directed transperineal (cTP) biopsy and transrectal ultrasonography (cTRUS) biopsy. METHODS: This was a retrospective single-centre study of consecutive men attending the private practice clinic of an experienced urologist performing MRI-guided biopsy and an experienced urologist performing cTP and cTRUS biopsy techniques for PI-RADS 3-5 lesions identified on 3-Tesla mpMRI. RESULTS: There were 595 target mpMRI lesions from 482 men with PI-RADS 3-5 regions of interest during 483 episodes of biopsy. The abnormal mpMRI target lesion was biopsied using the MRI-guided method for 298 biopsies, the cTP method for 248 biopsies and the cTRUS method for 49 biopsies. There were no significant differences in PCa detection among the three biopsy methods in PI-RADS 3 (48.9%, 40.0% and 44.4%, respectively), PI-RADS 4 (73.2%, 81.0% and 85.0%, respectively) or PI-RADS 5 (95.2, 92.0% and 95.0%, respectively) lesions, and there was no significant difference in detection of significant PCa among the biopsy methods in PI-RADS 3 (42.2%, 30.0% and 33.3%, respectively), PI-RADS 4 (66.8%, 66.0% and 80.0%, respectively) or PI-RADS 5 (90.5%, 89.8% and 90.0%, respectively) lesions. There were also no differences in PCa or significant PCa detection based on lesion location or size among the methods. CONCLUSION: We found no significant difference in the ability to detect PCa or significant PCa using targeted MRI-guided, cTP or cTRUS biopsy methods. Identification of an abnormal area on mpMRI appears to be more important in increasing the detection of PCa than the technique used to biopsy an MRI abnormality.