Total-Body ⁶⁸Ga-PSMA-11 PET/CT for Bone Metastasis Detection in Prostate Cancer Patients: Potential Impact on Bone Scan Guidelines

Abstract

Our purpose was to determine the relationship between serum prostate-specific antigen (PSA) level categories (,5, 5-10, 10-20, and .20 ng/mL) and the incidence of bone metastases detected by total-body 68 Ga-prostate-specific membrane antigen (PSMA)-11 PET/CT and to assess if expanding the 68 Ga-PSMA-11 PET/CT imaging field to include the vertex and lower extremities (total-body acquisition) affects bone metastasis detection rates and patient management. Methods: This was a retrospective analysis of 388 prostate cancer patients enrolled in 5 prospective studies (NCT02940262, NCT03368547, NCT03042312, NCT04050215, and NCT03515577). All underwent 68 Ga-PSMA-11 PET/CT scans acquired from vertex to toes for primary staging (n 5 93/388, 24%), biochemical recurrence (BCR) localization (n 5 225/388, 58%), or restaging metastatic disease (M1) before or during systemic therapy (n 5 70/388, 18%) between September 2017 and May 2018. Results: In total, 321 of 388 patients (83%) had a positive 68 Ga-PSMA-11 study. PSMA-positive bone lesions were found in 105 of 388 (27%) patients, with an incidence that was positively associated with serum PSA level (,10 ng/mL, 21%; 10-20 ng/mL, 41%; $20 ng/mL, 41%; P , 0.001). This association was maintained for all 3 indications: initial staging, BCR, and restaging M1. Bone metastases occurred most frequently in restaging M1, followed by BCR and initial staging. Bone metastasis incidence was not significantly associated with National Comprehensive Cancer Network risk score (P 5 0.22). The average number of PSMA-positive regions also increased with serum PSA level (P , 0.001). Eighteen of 388 (5%) and 18 of 388 (5%) had lesions above the superior orbital ridge and below the proximal third of the femur, respectively. There was only 1 of 388 patients (0.26%) in whom the totalbody PET acquisition had an impact on management. Conclusion: Bone metastases as assessed with 68 Ga-PSMA-11 PET/CT are prevalent even in patients with low serum PSA levels. Therefore, current guidelines for bone assessments in prostate cancer patients should be revisited because 68 Ga-PSMA-11 PET/CT may provide additional information for accurate bone staging at low serum PSA levels. Including the total body (from vertex to toes) in 68 Ga-PSMA-11 PET/CT imaging revealed additional bone lesions in 6% of patients, but without significantly affecting patient management.

Factors Predicting Metastatic Disease in 68Ga-PSMA-11 PET–Positive Osseous Lesions in Prostate Cancer

“…Ga-PSMA PET(20,23), superior to standard of care imaging including CT or bone scan. The purpose of this study was to evaluate the diagnostic accuracy of 68 Ga-PSMA-11 PET findings in by on November 1, 2020.…”

68Ga-PSMA-11 PET/CT Follow-Up of Patients with Prostate Cancer with Bone Metastases Who Had Reduced Bone Density after Androgen Deprivation Therapy

“…Monitoring the response of metastatic skeletal disease to treatment and early identification of castration resistance is an ongoing challenge. Measurement of PSA alone is not reliable enough for monitoring disease activity since visceral metastases may develop in men without rising PSA [ 4 ]. The Prostate Cancer Working Group (PCWG) 2 and 3 recommended a combination of bone scintigraphy and CT scans, PSA measurements, and clinical benefit in men with CRPC [ 21 ].…”

“…Prostate-specific membrane antigen (68Ga-PSMA-11) positron emission tomography/computed tomography (PET/CT) is highly sensitive and specific for detection of skeletal involvement in newly diagnosed prostate cancer patients. It has been shown to be superior to traditional bone scintigraphy (BS) as it allows for detection of lytic type and early marrow-based metastases in addition to osteoblastic-type metastases seen on BS [ 2 , 3 , 4 ]. In a recent study involving 112 prostate cancer patients, 68Ga-PSMA-11 PET/CT revealed bone metastases in 10% of the patients who were deemed to be non-metastatic on BS and in 36% of the patients with indeterminate BS [ 5 ].…”

Recent Advances in Nanomedicine for the Diagnosis and Treatment of Prostate Cancer Bone Metastasis

“…However, 11 C-choline accumulates in liver, kidney, spleen and pancreas, making assessment of the upper abdomen difficult [ 74 ]. More recently, the expression of the prostate-specific membrane antigen (PSMA) was targeted with 68 Ga-labeled PSMA ligands [ 75 , 76 ]. 68 Ga-PSMA-11 PET/CT assists in disease localization at biochemical recurrence (BCR), staging, and to select patients for PSMA-targeted molecular radiotherapy [ 75 ].…”