PSMA PET/CT SUVmax as a prognostic biomarker in patients with metachronous metastatic hormone-sensitive prostate cancer (mHSPC).

BACKGROUND: Metastatic hormone-sensitive prostate cancer (mHSPC) is treatment-resistant and generally considered incurable. The development of prostate-specific membrane antigen positron emission-computed tomography (PSMA PET/CT) has generated immense expectations due to its diagnostic accuracy in prostate cancer (PCa). PSMA expression of the primary tumor, quantified by SUVmax, is a predictor of oncological outcomes. The role of PSMA-PET/CT SUVmax in metachronous mHSPC treated with ADT plus second-generation antiandrogens (ARSI) is unknown. The main aim of this study was to evaluate 68Ga-PSMA-11expression (SUVmax) as a potential prognostic biomarker in patients with metachronous mHSPC treated with ADT and first or second-generation antiandrogens. A second aim was to determine the association between PSMA SUVmax and PSA response to hormone therapy. MATERIAL AND METHODS: Patients diagnosed with metachronous mHSPC between July 2017 and February 2023 who developed biochemical recurrence following radical surgery (with or without salvage radiotherapy and/or ADT) or external radiation therapy (with or without ADT) were included. All patients underwent 68 Ga-PSMA-11 PET/CT imaging and the SUVmax value was determined for all measurable locations. The SUVmax value was used for the semiquantitative analysis. The Wilcoxon method was used to compare responders (PSA reduction ≥ 50%) to non-responders (PSA reduction < 50%). The SUVmax value and hormone therapy were evaluated as independent variables relative to the PSA response rate or PSA reduction using the linear regression method. A mixed-effects model (ANOVA) was used for the comparisons. RESULTS: A total of 82 patients were included. Median follow-up was 11.7 months. On the linear regression analysis, patients with a high SUVmax treated with ADT + ARSI showed a greater PSA response (p = 0.034) than those treated with ADT + first-generation antiandrogens. In the mixed-effects model, SUVmax was significant (p = 0.041). On the univariate analysis, PSA at recurrence (HR, 3.2; 95% CI: 1.07-13.6; p = 0.078) and the number of metastases (HR, 4.77; 95% CI 1.1-26.1: p = 0.002) were associated with the type of hormone therapy administered. CONCLUSIONS: PSMA-PET/CT SUVmax is a prognostic biomarker that can be used to predict a PSA response to ADT + ARSI in patients with metachronous mHSPC. However, these findings need to be confirmed in larger prospective studies.

Superscan on 68Ga PSMA PET/CT in patients with metastatic prostate carcinoma: A case series.

Prostate cancer is the second most common malignancy in men worldwide, with a good prognosis when is detected and treated in early stages, but, when it presents progression to castration-resistant metastatic prostate cancer, most of the cases will have bone metastasis, decreasing the quality of life and life expectancy. For the evaluation of the disease in the routinary clinical practice, 68Ga-PSMA PET/CT, among others is a valuable tool for the evaluation of the disease extension. 68Ga-PSMA PET/CT detects the presence of PSMA receptor in the tumoral tissue, but also has physiologic uptake in certain organs, such as liver, spleen, intestine, kidneys, lacrimal and salivary glands. Total or partial absence of uptake in those organs is rare and may be due to a high metastatic tumor burden, a phenomenon originally described in bone scintigraphy as super scan. We describe a case series of seven patients with prostate cancer from the National Institute of Cancerology in Colombia, in which a super scan pattern was found in the evaluation with 68Ga-PSMA PET/CT, proposing the suppression of uptake in the intestine, liver, spleen, lacrimal and salivary glands as the main criteria for its definition, and showing that renal uptake persists in most cases, considering that, unlike the super scan in conventional bone scintigraphy, this is not a criterion necessary for its definition in the study with 68Ga-PSMA.

Metabolic response after 68Ga-PSMA-PET/CT-directed IGRT/SBRT for oligometastases prostate cancer.

BACKGROUND: We used 68Ga PSMA PET/CT in the current investigation to assess the metabolic response and local control of metastasis in patients with oligometastatic prostate cancer receiving SBRT. MATERIALS AND PROCEDURES: We performed a retrospective evaluation of the medical data of all patients with oligometastatic prostate cancer who underwent stereotactic body radiation therapy (SBRT) between 2017 and 2021. Our analysis only included medical records of patients who had SBRT for oligometastatic prostate cancer and had pre and post-SBRT 68Ga PSMA PET/CT images. Patient-related (age), disease-related (Gleason score, location of metastases), and treatment-related (factors and outcomes) data were collected from the medical files. RESULTS: A total of 17 patients (28 lesions) with a median age of 69 years were included in the research. A median follow-up of 16.6 months was used (range 6-36 months). The median follow-up period for 68 Ga PSMA PET/CT was 8 months (the range was 5-24 months). The median pre-treatment PSA level was 1.7 ng/mL (range 0.39-18.3 ng/mL) compared to the post-treatment PSA nadir of 0.05 ng/mL (0.02-4.57). During the follow-up period, local control was 96%, and there was a link between PSMA avidity on PET. In the treated lesions, there were no recurrences. During follow-up, none of the patients experienced toxicities of grade 3 or above. CONCLUSIONS: SBRT is a highly successful and safe way of treating patients with oligometastatic prostate cancer. Additional research is needed to examine 68Ga PSMA PET/CT to assess further for demarcation and follow-up.

Schwannoma: A rare cause of false-positive 68Ga-PSMA PET/CT uptake in the evaluation of metastatic prostate cancer.

PSMA expression occurs in epithelial cells in both normal and hyperplastic prostates. In adenocarcinoma, it is present in greater intensity, especially in the more aggressive ones. This made it possible to develop diagnostic tools with greater specificity for detecting prostate cancer metastases like the 68Ga-PSMA PET/CT. Several benign neoplasms with increased marker uptake have been described in the literature. Such false-positives are usually associated with soft tissue injuries, abnormal vascular proliferation, neurogenic injuries, thymomas and adenomas. In the present work we present a case report that exemplifies the above.

PSMA-PET and micro-ultrasound potential in the diagnostic pathway of prostate cancer.

PURPOSE: To compare the diagnostic performance of 68Ga-PSMA PET/TC with PRI-MUS (prostate risk identification using micro-ultrasound) in the primary diagnosis of prostate cancer (PCa). METHODS: From September till December 2018, we prospectively enrolled 25 candidates to 68Ga-PSMA PET/TRUS (transrectal ultrasound) fusion biopsy and compared them with PRI-MUS. This included patients with persistently elevated PSA and/or PHI (prostate health index) suspicious for PCa, negative digital rectal examination, with either negative or contraindication to mpMRI, and at least one negative biopsy. The diagnostic performance of the two modalities was calculated based on pathology results. RESULTS: Overall, 20 patients were addressed to 68Ga-PSMA PET/TRUS fusion biopsy. Mean SUVmax and SUVratio for PCa lesions resulted significantly higher than in benign lesions (p = 0.041 and 0.011, respectively). Using optimal cut-off points, 68Ga-PSMA PET/CT demonstrated an overall accuracy of 83% for SUVmax ≥ 5.4 and 94% for SUVratio ≥ 2.2 in the detection of clinically significant PCa (GS ≥ 7). On counterpart, PRI-MUS results were: score 3 in nine patients (45%), score 4 in ten patients (50%), and one patient with score 5. PRI-MUS score 4 and 5 demonstrated an overall accuracy of 61% in detecting clinically significant PCa. CONCLUSION: In this highly-selected patient population, in comparison to PRI-MUS, 68Ga-PSMA PET/CT shows a higher diagnostic performance.

Detection rate, pattern of relapse and influence on therapeutic decision of PSMA PET/CT in patients affected by biochemical recurrence after radical prostatectomy, a retrospective case series.

AIMS: 68Ga-Prostate-specific membrane antigen (PSMA) PET/CT is widely used in patients with biochemical recurrence (BCR) after radical prostatectomy. We collected data about patients staged with PSMA PET/CT after BCR (PSA < 1 ng/ml) in four different institutes. Impact of baseline features (Gleason score, risk classification, PSA at recurrence, PSA doubling time and time to recurrence) was explored to understand predictive factors of (PSMA) PET/CT positivity. Impact of restaging on following treatment approaches was reported. RESULTS: 92 patients were included. PSMA PET/CT detection rate was 56.5% and low-volume disease (≤ 3 non-visceral lesions) was detected in 52.2% of patients. After positive scan, 13.5% of patients still lies on observation, ADT alone was administered in 30.8% of cases, Stereotactic body RT (SBRT) alone was delivered to 44.2% of patients and 11.5% of patients underwent concomitant SBRT and ADT. Seven patients underwent conventional salvage prostate bed RT. Chi-squared test showed a higher rate of positive PSMA PET/CT for patients with Gleason score > 7 (p = 0.004) and TTR < 29.5 months (p = 0.003). CONCLUSIONS: PSMA PET/CT showed a high detection rate. This influenced clinical management in a significant percentage of patients, allowing treatment tailoring on the basis of imaging.