Detection of Recurrent Prostate Cancer With 18F-Fluciclovine PET/MRI

Up-to-Date Imaging and Diagnostic Techniques for Prostate Cancer: A Literature Review

Prostate cancer (PCa) faces great challenges in early diagnosis, which often leads not only to unnecessary, invasive procedures, but to over-diagnosis and treatment as well, thus highlighting the need for modern PCa diagnostic techniques. The review aims to provide an up-to-date summary of chronologically existing diagnostic approaches for PCa, as well as their potential to improve clinically significant PCa (csPCa) diagnosis and to reduce the proliferation and monitoring of PCa. Our review demonstrates the primary outcomes of the most significant studies and makes comparisons across the diagnostic efficacies of different PCa tests. Since prostate biopsy, the current mainstream PCa diagnosis, is an invasive procedure with a high risk of post-biopsy complications, it is vital we dig out specific, sensitive, and accurate diagnostic approaches in PCa and conduct more studies with milestone findings and comparable sample sizes to validate and corroborate the findings.

The Performance of FDA-Approved PET Imaging Agents in the Detection of Prostate Cancer

Positron emission tomography (PET) incorporated with X-ray computed tomography (PET/CT) or magnetic resonance imaging (PET/MRI) is increasingly being used as a diagnostic tool for prostate cancer (PCa). In this review, we describe and evaluate the clinical performance of some Food and Drug Administration (FDA)-approved agents used for visualizing PCa: [¹⁸F]FDG, [¹¹C]choline, [¹⁸F]FACBC, [⁶⁸Ga]Ga-PSMA-11, [¹⁸F]DCFPyL, and [¹⁸F]-NaF. We carried out a comprehensive literature search based on articles published from 1 January 2010 to 1 March 2022. We selected English language articles associated with the discovery, preclinical study, clinical study, and diagnostic performance of the imaging agents for the evaluation. Prostate-specific membrane antigen (PSMA)-targeted imaging agents demonstrated superior diagnostic performance in both primary and recurrent PCa, compared with [¹¹C]choline and [¹⁸F]FACBC, both of which target dividing cells and are used especially in patients with low prostate-specific antigen (PSA) values. When compared to [¹⁸F]-NaF (which is suitable for the detection of bone metastases), PSMA-targeted agents were also capable of detecting lesions in the lymph nodes, soft tissues, and bone. However, a limitation of PSMA-targeted imaging was the heterogeneity of PSMA expression in PCa, and consequently, a combination of two PET tracers was proposed to overcome this obstacle. The preliminary studies indicated that the use of PSMA-targeted scanning is more cost efficient than conventional imaging modalities for high-risk PCa patients. Furthering the development of imaging agents that target PCa-associated receptors and molecules could improve PET-based diagnosis of PCa.

[18F]Fluciclovine PET/CT Improves the Clinical Management of Early Recurrence Prostate Cancer Patients

Simple Summary

In the challenge between increasingly sensitive PET radiopharmaceuticals for the evaluation of prostate cancer patient in biochemical relapse, the choice of the most accurate PET tracer must be guided by literature data, but above all tailored to the patient’s profile. In describing our single-center experience, we aimed to identify biochemical and clinical–histological factors to be considered in patient selection and the semiquantitative parameters that can help the interpretation of malignant from benign lesions, in order to optimize the performance of this imaging method. These data in combination with a significant impact on therapeutic decision making can be useful to further validate the [¹⁸F]Fluciclovine PET/CT clinical application.

Abstract

We investigated the [¹⁸F]Fluciclovine PET/CT reliability in the early detection of recurrent prostate cancer (PCa) and its impact on therapeutic decision making. We retrospectively analyzed 58 [¹⁸F]Fluciclovine PET/CT scans performed to identify early PCa recurrence. Detection rate (DR) and semiquantitative analysis were evaluated in relation to biochemical and clinical–histological features. Clinical follow-up data were collected and considered as gold standard to evaluate sensitivity, specificity, accuracy, positive and negative predictive value (PPV, NPV). The impact of [¹⁸F]Fluciclovine PET/CT on clinical management was also assessed. Overall DR resulted as 66%, while DR was 53%, 28%, and 7% in prostate/bed, lymph nodes, and bone, respectively. DR significantly increased with higher PSA values (p = 0.009) and 0.45 ng/mL was identified as the optimal cut-off value. Moreover, SUVmax and SUVmean resulted significant parameters in interpreting malignant from benign findings. [¹⁸F]Fluciclovine PET/CT reached a sensitivity, specificity, PPV, NPV, and accuracy of 87.10%, 80.00%, 87.10%, 80.00%, and 84.31%, respectively. Therapeutic strategy was changed in 51% of patients. Our results support [¹⁸F]Fluciclovine PET/CT as a reliable tool for early restaging of PCa patients, especially for local recurrence detection, leading to a significant impact on clinical management. Semiquantitative analysis could improve specificity in interpreting malignant from benign lesions.

Impact of 18F-fluciclovine PET/CT on salvage radiotherapy plans for men with recurrence of prostate cancer postradical prostatectomy

OBJECTIVES

Imaging options to localize biochemical recurrence (BCR) of prostate cancer after radical prostatectomy (RP) are limited, especially at low prostate-specific antigen (PSA) levels. The FALCON study evaluated the impact of 18F-fluciclovine PET/CT on management plans for patients with BCR. Here, we evaluate salvage radiotherapy decisions in patients post-RP.

METHODS

We conducted a subgroup analysis of post-RP patients enrolled in FALCON who had a prescan plan for salvage radiotherapy (± androgen-deprivation therapy). Patients' treatment plans post-18F-fluciclovine PET/CT were compared with their prescan plans. Fisher exact test was used to determine the impact of PSA and Gleason sum on positivity and anatomical patterns of uptake.

RESULTS

Sixty-five (63%) FALCON patients had undergone RP. Of these, 62 (median PSA, 0.32 ng/mL) had a prescan plan for salvage radiotherapy. Twenty-one (34%) had 18F-fluciclovine-avid lesions. Disease was confined to the prostate bed in 11 patients (52%) and to the pelvis in a further 5 (24%), while 5 (24%) had extrapelvic findings. Trends towards more disseminated disease with increasing PSA or Gleason sum were observed but did not reach statistical significance. Postscan, 25 (40%) patients had a management change; 17 (68%) were changed to the treatment modality (8 to systemic therapy, 8 to active surveillance, 1 other) and 8 (32%) were radiotherapy field modifications.

CONCLUSIONS

Incorporating 18F-fluciclovine PET/CT into treatment planning may help identify patients suitable for salvage radiotherapy, help augment planned radiotherapy to better target lesions and support the clinician to optimise patient management.

Risk of metastatic disease using [18F]PSMA-1007 PET/CT for primary prostate cancer staging

BACKGROUND

Accurate prostate cancer imaging is critical for patient management. Multiple studies have demonstrated superior diagnostic accuracy of [⁶⁸Ga]-PSMA-11 PET/CT over conventional imaging for disease detection, with validated clinical and biochemical predictors of disease detection. More recently [¹⁸F]PSMA-1007 offers theoretical imaging advantages, but there is limited evidence of clinical and biochemical predictors of scan findings in the staging population. This study investigates the association of clinical variables with imaging characteristics among patients who underwent [¹⁸F]PSMA-1007 PET/CT for primary staging of men with histopathologically confirmed prostate carcinoma. A retrospective review of 194 consecutive patients imaged between May 2019 to May 2020 was performed. Association between imaging variables (presence and distribution of metastatic disease, primary tumour SUVmax) and clinical variables (EAU risk criteria) were assessed using descriptive statistics, logistic regression model and ROC analysis.

RESULTS

The median age, PSA level and ISUP grade were 70 years, 10 ng/mL and ISUP grade 3, respectively. There were 36.6% of patients with intermediate-risk and 60.8% of patients with high-risk disease. ISUP grade was associated with the presence of metastasis overall (p = 0.008) as well as regional nodal (p = 0.003), non-regional nodal (p = 0.041) and bone (p = 0.006) metastases. PSA level was associated with metastatic disease overall (p = 0.001), regional (p = 0.001) and non-regional nodal metastases (p = 0.004), but not with bone metastases (p = 0.087). There were too few visceral metastases for meaningful analysis. SUVmax of the primary prostatic tumour was associated with ISUP grade (p = 0.004), PSA level (p < 0.001) and AJCC stage (p = 0.034). PSA > 20 ng/mL and ISUP grade > 3 had a specificity of 85% (95% CI 78-91%) and 60% (95% CI 50-68%) and a sensitivity of 36% (95% CI 25-49%) and 62% (95% CI 49-74%), respectively, for detection of metastatic disease.

CONCLUSION

Metastatic disease according to [¹⁸F]PSMA-1007 PET/CT was associated with ISUP grade and PSA level. This is the largest study using [¹⁸F]PSMA-1007 PET/CT to confirm a positive correlation of PSA level, ISUP grade and stage with primary prostate tumour SUVmax.

18F-Fluciclovine PET/CT performance in biochemical recurrence of prostate cancer: a systematic review

BACKGROUND

A systematic literature review of the performance of 18Fluorine-fluciclovine PET/CT for imaging of men with recurrent prostate cancer was performed.

METHODS

Scientific literature databases (MEDLINE, ScienceDirect and Cochrane Libraries) were searched systematically during Oct 2020 using PRISMA criteria. No limit was put on the date of publication. Prospective studies reporting a patient-level 18F-fluciclovine detection rate (DR) from ≥25 patients with recurrent prostate cancer were sought. Proceedings of relevant meetings held from 2018 through Oct 2020 were searched for abstracts meeting criteria.

RESULTS

Searches identified 321 unique articles. In total, nine articles (six papers and three conference abstracts), comprising a total of 850 patients met inclusion criteria. Most studies (n = 6) relied on ASTRO-Phoenix Criteria, EAU-ESTRO-SIOG, and/or ASTRO-AUA guidelines to identify patients with biochemical recurrence. Patients' PSA levels ranged from 0.02-301.7 ng/mL (median level per study, 0.34-4.10 ng/mL [n = 8]). Approximately 64% of patients had undergone prostatectomy, but three studies focused solely on post-prostatectomy patients. Adherence to imaging protocol guidelines was heterogeneous, with variance seen in administered activity, uptake and scan times. Overall patient-level DR varied between studies from 26% to 83%, with 78% of studies reporting a DR > 50%. DR was proportional to PSA, but even at PSA < 0.5 ng/mL DR of up to 53% were reported. Prostate/bed DR (n = 7) ranged from 18% to 78% and extra-prostatic rates (n = 6) from 8% to 72%. Pelvic node and bone lesion DR ranged from 8% to 47% and 0% to 26%, respectively (n = 5). 18F-Fluciclovine PET/CT was shown to impact patient management and outcomes. Two studies reported 59-63% of patients to have a management change post-scan. A further study showed significant increase in failure-free survival following 18F-fluciclovine-guided compared with conventional imaging-guided radiotherapy planning.

CONCLUSIONS

18F-Fluciclovine PET/CT shows good performance in patients with recurrent prostate cancer leading to measurable clinical benefits. Careful adherence to recommended imaging protocols may help optimize DR.

Applications of PET/MRI in Abdominopelvic Oncology

With PET/MRI, the strengths of PET and MRI are combined to allow simultaneous image acquisition and near-perfect image coregistration. MRI is increasingly being used for staging and restaging of abdominopelvic oncologic lesions, including prostate, hepatobiliary, pancreatic, neuroendocrine, cervical, and rectal cancers. Fluorine 18-fluorodeoxyglucose PET/CT has long been considered a cornerstone of oncologic imaging, and the development of multiple targeted radiotracers has led to increased research on and use of these agents in clinical practice. Thus, simultaneously performed PET/MRI enables the acquisition of complementary imaging information, with distinct advantages over PET/CT and MR image acquisitions. The authors provide an overview of PET/MRI, including descriptions of the major differences between PET/MRI and PET/CT, as well as case examples and treatment protocols for patients with commonly encountered malignancies in the abdomen and pelvis. Online supplemental material is available for this article. ^©RSNA, 2021.