Is There Any Role for 18F-Fluciclovine PET/CT in the Presence of Undetectable PSA in Prostate Cancer Patients After Definitive Treatment?

Diagnostic Performance of PSMA-Based 18 F-DCFPyL PET/CT in Prostate Cancer Patients After Definitive Treatment With PSA Level ≤0.2 ng/mL

PURPOSE

The aim of this study was to investigate the role of 18 F-DCFPyL PET/CT in the evaluation of prostate cancer (PC) patients after definitive treatment and with low-level prostate-specific antigen (PSA) level of ≤0.2 ng/mL.

PATIENTS AND METHODS

This retrospective study was conducted in PC patients who received definitive treatments with PSA level of ≤0.2 ng/mL and underwent 18 F-DCFPyL PET/CT within a 1-week interval of PSA examination, and without interval treatment change or history of other cancer. Patient and tumor characteristics at initial diagnosis, treatment regimens, and findings on 18 F-DCFPyL PET/CT were collected. Patients with minimal 6-month (median, 11 months; range, 6-21 months) follow-up or definitive biopsy results of the suspected PET/CT findings were included. Imagine findings were reached with consensus among experienced board-certified nuclear medicine physicians. Comprehensive follow-up and/or biopsy results were used as definitive determination of presence or absence of disease. Comparisons between groups of positive and negative 18 F-DCFPyL PET/CT were done by using descriptive statistics.

RESULTS

A total of 96 18 F-DCFPyL PET/CTs from 93 patients met the inclusion criteria. The median Gleason score (GS) of positive group is 8 (range, 6-10), whereas negative group is 7 (range, 6-10). The median age of positive group is 71 (range, 50-90), whereas negative group is 69 (range, 45-88). There were 49 positive (51%) and 47 negative 18 F-DCFPyL PET/CTs (49%). Detection rates at PSA level of ≤0.1 and 0.2 ng/mL were 58.7% (27/46) and 44% (22/50), respectively. The scan-based sensitivity, specificity, positive predictive value, and negative predictive value are 100%, 95%, 96%, and 100% in group with PSA level of ≤0.1 ng/mL, and 100%, 97%, 95%, and 100% in group with PSA level of 0.2 ng/mL, respectively. Sites of involvement on positive 18 F-DCFPyL PET/CTs were prostate bed, pelvic lymph nodes, bone, chest and supraclavicular lymph nodes, lung, and adrenal glands. The SUV max value on positive lesions ranged from 1.9 to 141.4; the smallest positive lymph node was 0.4 cm. High GS of 8-10, known metastatic status (M1), presence of extraprostatic extension, presence of seminal vesicle invasion, and very high-risk PC are significantly associated with positive 18 F-DCFPyL PET/CT results ( P < 0.05). Of all analyzed treatment regimes, upfront surgery (radical prostatectomy with or without pelvic lymph node dissection) had strong correlation with negative PET/CT results ( P < 0.001). If patients received ADT only, or ADT plus chemotherapy, the PET/CT results were most likely positive ( P = 0.026). For other treatment regimes, there were no statistical differences between the groups ( P > 0.05).

CONCLUSIONS

In the presence of low PSA level in PC patients after definitive treatment, 18 F-DCFPyL PET/CT is most beneficial in detection of disease in patients with GS of 8 or higher at the time of diagnosis, and the ones who have history of ADT only, or ADT plus chemotherapy. There is excellent negative prediction value of 18 F-DCFPyL PET/CT. However, there is no cutoff PSA level for 18 F-DCFPyL PET/CT indication and no correlation between PSA level and SUV max of positive lesions on 18 F-DCFPyL PET/CT.

18 F-Fluciclovine PET Detected Early Tumor Recurrence in Prostatectomy Bed With Low PSA of 0.3 ng/mL But Negative on 18 F-PSMA PET Scan

ABSTRACT

A 58-year-old man with metastatic prostate cancer was treated with prostatectomy, radiation therapy to bone metastasis, and androgen deprivation therapy plus abiraterone. He had posttreatment nadir PSA of 0.1 ng/mL. A follow-up 18 F-fluciclovine PET performed with PSA of 0.3 ng/mL showed a focal tracer-avid lesion in the left prostatectomy bed. This lesion was negative on 18 F-DCFPyL PET/CT, but with typical MRI features for disease recurrence. Minimal urinary activity of fluciclovine helped detection of local disease recurrence in the prostatectomy bed.

[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.

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.

Positivity Rate of [18F]Fluciclovine PET/CT in Patients with Suspected Prostate Cancer Recurrence at PSA Levels Below 1 ng/mL

PURPOSE

Early and precise localization of recurrent prostate cancer lesions after local therapy facilitates optimal disease management. Here, we present results from a single-center study to evaluate the utility of [¹⁸F]fluciclovine PET/CT to localize prostate cancer recurrence in patients with PSA <1 ng/mL.

PROCEDURES

Data from men who underwent [¹⁸F]fluciclovine PET/CT (August 2016-March 2020) for suspected recurrent prostate cancer and who had a PSA value <1ng/mL were retrospectively reviewed. The number of positive scans (positivity rates, PR) was calculated for the whole body, prostate/bed, and extraprostatic regions (pelvic or extrapelvic lymph nodes, bones, and soft tissue). PR were stratified by pre-scan PSA.

RESULTS

Data from 113 patients were included. In total, 98 (87%) were post-prostatectomy and 15 (13%) had received non-surgical primary therapy. Twenty patients (18%) were receiving ADT at the time of the scan, 91 (81%) were not, and ADT status was not known for 2 (1.8%) patients. The overall PR at PSA <1ng/mL was 59% (67/113). For the prostate/bed, it was 35% (40/113), and for extraprostatic locations, it was 37% (42/113). At PSA >0-<0.2, 0.2-<0.5, and 0.5-<1 ng/mL, the overall PR was 43% (10/23), 70% (35/50), and 55% (22/40), respectively. In the prostate/bed, these were 13% (3/23), 50% (25/50), and 30% (12/40), respectively, and in extraprostatic lesions were 30% (7/23), 44% (22/50), and 33% (13/40), respectively. Pelvic lymph nodes were the most common site for extraprostatic lesions (29/113, 26%). PR in extrapelvic lymph nodes, bone, and soft tissue were 8.0%, 12%, and 3.5%, respectively. Soft tissue lesions comprised lung nodules (n=3) and a perirectal mass implant (n=1).

CONCLUSIONS

Despite low PSA values, more than half of patients had positive [¹⁸F]fluciclovine PET/CT findings. Patients with low PSA levels may demonstrate suspicious findings outside of the pelvis, including abdominal lymph nodes and metastatic disease to bones and lungs.