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Introduction: Current guidelines don't support the use of pretreatment imaging in patients with favorable intermediate-risk prostate cancer. 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) is more accurate than conventional imaging for preoperative staging. We aimed to evaluate whether pretreatment 68Ga-PSMA PET/CT is beneficial for identifying pathological lymph node involvement (LNI) and adverse pathology among patients with favorable intermediate-risk prostate cancer. Methods: We reviewed 88 patients with favorable intermediate-risk prostate cancer who underwent 68Ga-PSMA PET/CT prior to radical prostatectomy and lymph node dissection from 2016-2020. The primary endpoint was the presence of pathological LNI. Association between pretreatment characteristics and outcomes were evaluated. Results: Preoperative 68Ga-PSMA PET/CT showed suspicious uptake in lymph nodes in 4/88 patients (5%), hence, 20 patients would need to be scanned to identify a patient with a positive lymph node on imaging. Two patients had pathological LNI, only one of whom showed 68Ga-PSMA PET/CT uptake prior to surgery. The sensitivity, specificity, positive predictive value, and negative predictive values of 68Ga-PSMA PET/CT for identifying LNI were 50%, 97%, 25%, and 99%, respectively. After surgery, four patients had evidence of prostate-specific antigen (PSA) persistence. The rate of PSA persistence was higher among patients with LNI on preoperative 68Ga-PSMA PET/CT (2/4, 50% vs. 2/84, 2%, p=0.009). Conclusions: Preoperative imaging of favorable intermediate-risk prostate cancer patients using 68Ga-PSMA PET/CT showed a low yield for identifying patients at higher risk. Consistent with current guidelines, our findings do not support the routine use of PET/CT in this group of patients. Future prospective studies are needed to validate our findings. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to elaborate the incidence and type of skeletal involvement in a large cohort of patients with newly diagnosed prostate cancer (PCa) referred for Ga-68 PSMA-11 PET/CT staging in a single center. Methods: Study cohort included 963 consecutive patients with newly diagnosed PCa referred for Ga-68 PSMA-11 PET/CT study for staging. The incidence of bone involvement, type of bone metastases, and extent of disease were determined and correlated with the ISUP Grade Group (GG) criteria and PSA levels. Results: Bone metastases were found in 188 (19.5%) of 963 patients. Bone metastases were found in 10.7% of patients with PSA < 10 ng/dL and in 27.4% of patients with PSA > 10 ng/dL and in 6.1% of patients with GG ≤ 2/3 and in 8.9% of patients with GG 4/5. In 7.6% of the patients, skeletal involvement was extensive, while 11.9% of patients had oligometastatic disease. Osteoblastic type metastases were the most common type of bone metastases presented in 133 of the patients with malignant bone involvement (70.7%). More than half of them had only osteoblastic lesions (72 patients (38.3%)), while the other (61 patients (32.5%)) had also intramedullary and/or osteolytic type lesions. Intramedullary metastases were found in 97 patients (51.6%), while 41 (21.8%) of them were only intramedullary lesions. Osteolytic metastases were detected in 36 patients (19.2%), of which 8 were only osteolytic lesions. Conclusion: Although traditionally bone metastases of PCa are considered osteoblastic, osteolytic and intramedullary metastases are common, as identified on PET with labeled PSMA. Skeletal spread may be present also in patients with GG ≤ 2/3 and PSA < 10 ng/dL. [ABSTRACT FROM AUTHOR]

Bone metastases from prostate cancer (PCa) often show an increase in density on computed tomography (CT) after successful androgen deprivation therapy (ADT). Density may be reduced, however, as the disease progresses or, contrarily, when disease is no longer active. The current study investigated the role of 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in differentiating between these two conditions. Methods: The study cohort included 15 PCa patients with sclerotic/blastic bone metastasis in whom reduction in bone density of metastasis was noted on follow-up 68Ga-PSMA-11 PET/CT after ADT. Each patient had two PET/CT scans. Prior to the first scan, six patients were castration naïve and nine patients were already treated. All patients had ADT between the two PET/CT scans. PET parameters (SUVmax and tumor-to-background ratio), and CT parameters (HUmax) were determined and compared for each lesion on both scans. Patient's response was based on prostate-specific antigen (PSA) levels and appearance of new lesions. The Kolmogorov–Smirnov test was used to evaluate normal distribution of the continuous variables. Results: Post-ADT reduction in bone density was identified in 37 lesions. The mean HUmax was 883.9 ± 175.1 on the first scan and 395.6 ± 157.1 on the second scan (p < 0.001). Twenty-one of the 37 lesions showed no increased tracer uptake on the second PET/CT scan raising the likelihood of a response. The other 16 lesions were associated with increased uptake suggestive of an active resistant disease. Bone density was not different in lesions that no longer showed an increased uptake as compared with those that did. Seven of the study patients responded to therapy, and none of the 16 lesions found in these patients showed increased 68Ga-PSMA-11 uptake. In eight patients with progressive disease, all 12 lesions in five of them showed increased 68Ga-PSMA-11 uptake, there was mixed response in two patients (having two lesions with increased uptake and one without) and although all three lesions no longer showed an increased uptake, new lesions were detected in the eighth patient. Conclusion: A decrease in density of bone lesions may reflect clinical progression, or contrarily, a response to therapy in patients with PCa and skeletal involvement treated with ADT. Uptake of 68Ga-PSMA-11 may separate between these two vastly opposing conditions. [ABSTRACT FROM AUTHOR]

Introduction: Data on the accuracy of 68Ga-PSMA positron emission tomography/computed tomography (PET/CT) in patients with intermediate/high-risk prostate cancer are being accumulated. Its role in assessing the extent of local disease has not been fully elaborated.Aim: To determine the performance characteristics of 68Ga-PSMA PET/CT in identifying local disease extension in patients with intermediate/high risk prostate cancer.Methods: 68Ga-PSMA PET/CT studies of 61 consecutive patients with intermediate/high-risk prostate cancer who underwent radical prostatectomy were reviewed by nuclear medicine specialists. Tumor location, extraprostatic extension (EPE), seminal vesicle invasion (SVI), and lymph nodes involvement (LNI) were compared to pathological findings. The incremental value of 68Ga-PSMA PET/CT to established nomograms was determined.Results: Two patients without pathologic uptake of 68Ga-PSMA were excluded. Seventeen patients were diagnosed with EPE (29%), 12(20%) had SVI and 3(5%) LNI. The concordance between tumor location and 68Ga-PSMA PET/CT findings was 48%, and EPE was not indicated by PET in any of the patients. The sensitivity, specificity, positive, and negative predictive value for SVI were 58%, 96%, 78%, 90%, respectively (area under the receiver operating characteristic curve = 0.77) and for LNI 67%, 98%, 67%, 98%, respectively (area under the receiver operating characteristic curve = 0.82). Incorporating imaging findings into the MSKCC-SVI nomogram enhanced the diagnostic accuracy from 0.84 to 0.95 (Integrated Discrimination Increment 0.24, P = 0.004).Conclusion: In patients with intermediate/high-risk prostate cancer, 68Ga-PSMA PET/CT provides information regarding intraprostatic tumor location, SVI and LNI but has no role in assessment for EPE. This information might be useful for pretreatment counseling, decision-making and possibly preoperative planning. [ABSTRACT FROM AUTHOR]

Background: The aim of the current study was to assess whether and to what extent monitoring response to treatment using prostate-specific membrane antigen (PSMA)-based positron-emitting tomography/computerized tomography (PET/CT) studies contribute clinically relevant data to routine clinical follow-up during treatment of patients with metastatic prostate cancer (PCa). Results: Fifty-two patients with metastatic PCa who underwent [68Ga]Ga-PSMA-11 PET/CT imaging and serum prostate-specific antigen (PSA) level measurements before and during treatment were investigated. Response was categorized by serum PSA dynamics according to improvement, stable disease, and disease progression and compared to change in imaging findings on pre- and post-treatment PET/CTs. McNemar's test was used to assess agreement between PET/CT- and PSA-based responses to treatment. Thirty-four patients (65.4%) had compatible biochemical- and imaging-based response to treatment. However, the imaging and biochemical responses were discrepant in 18/52 patients (34.6%). PET/CT showed progressive disease in 5/52 patients (9.6%) and improvement/stable disease in 13/52 (25%) compared to biochemical assessment results. Discrepancy between imaging and biochemical response was most prominent in biochemically stable patients (90.9%), followed by patients with biochemical progression (33.3%), and in only few (8.7%) patients with biochemical improvement. The imaging-based response was suitable for choosing subsequent treatment in 22 of 30 patients (73.3%) with longer follow-up (median time of 10.3 months (IQR 6.3–18.2)). The relevance of the imaging methodology was reflected by its ability to assess individual lesions in cases of heterogeneous lesion responses, reveal the appearance of new lesions, and identify lesions that required specific consideration, such as targeted radiotherapy. Conclusions: Results of this retrospective analysis showed that biochemical responses to treatment and [68Ga]Ga-PSMA-11 PET/CT-based responses to treatment differ in one third of metastatic PCa patients. The latter additionally enabled lesion-based and not solely patient-based analysis. Monitoring response during treatment by [68Ga]Ga-PSMA-11 PET/CT is suitable for decision-making in patient management and choice of treatment in the majority of patients. [ABSTRACT FROM AUTHOR]