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World J Nucl Med. 2019 Jul-Sep;18(3):244-250. doi: 10.4103/wjnm.WJNM_47_18.

Initial experience of Ga-68 prostate-specific membrane antigen positron emission tomography/computed tomography imaging in evaluation of biochemical recurrence in prostate cancer patients.

Author information

1
Department of Nuclear Medicine and Molecular Imaging, Uro-Oncology Disease Management Group, Tata Memorial Hospital, Mumbai, Maharashtra, India.
2
Department of Radiation Oncology, Uro-Oncology Disease Management Group, Tata Memorial Hospital, Mumbai, Maharashtra, India.
3
Department of Surgical Oncology, Uro-Oncology Disease Management Group, Tata Memorial Hospital, Mumbai, Maharashtra, India.
4
Department of Medical Oncology, Uro-Oncology Disease Management Group, Tata Memorial Hospital, Mumbai, Maharashtra, India.

Abstract

Gallium-68 labeled prostate-specific membrane antigen (Ga-68 PSMA) ligand (HBED-CC) is a novel tracer used for prostate cancer imaging. The aim of the study was to investigate the performance of Ga-68 PSMA positron emission tomography/computed tomography (PET/CT) in patients with biochemical recurrence (BCR) after definitive treatment. Scans of 96 consecutive patients were analyzed. Sixty-two patients received external beam radiotherapy, 34 underwent radical prostatectomy (RP), and 20 patients were on androgen deprivation therapy. Patients with prostate-specific antigen (PSA) level ≥>0.2 ng/mL following RP and PSA rise by 2 ng/mL or more above the nadir PSA following RT (Phoenix criteria) was considered as BCR, respectively. All patients underwent contrast-enhanced PET/CT after injection of 67-111 MBq Ga-68 PSMA ligand. Detection rates were correlated with serum PSA level. Detection rate for nodal metastases was compared with CT. Results of the scan were validated by using either biopsy or follow-up imaging or clinical follow-up. Seventy-four (77%) patients showed abnormal finding in Ga-68 PSMA PET/CT. The median serum PSA level of the population was 5.5 ng/ml (range 0.2-123 ng/ml). The median PSA of the positive scans was higher than that of the negative scans (6 vs. 1.7 ng/ml) and was statistically significant (P = 0.001 by Mann-Whitney U-test). In post-RP group, the detection rates were 23%, 50%, and 82% for PSA <1, 1-2, and >2 ng/ml, respectively. For post-RT, the detection was 86%, 85%, and 95% for PSA 2-5, 5.1-10, and >10 ng/ml, respectively. PSMA PET/CT revealed nodal metastases in 52 (54%) patients while CT showed pathological nodes only in 27 (28%) patients. Overall PSMA PET/CT revealed more number of nodes than CT (111 vs. 48 nodal station). PSMA PET/CT showed relapse in prostate/prostatic bed in 26 (27%) patients, nodal metastases in 50 (52%), skeletal metastases in 20 (21%), and other sites in 4 (4%) patients. Ga-68 PSMA PET/CT has high detection rate for localizing the site of recurrence in patients with biochemical failure and is superior to CT scan in the detection of nodal disease.

KEYWORDS:

Biochemical failure; Gallium-68 Prostate-specific membrane antigen; biochemical recurrence; positron emission tomography; prostate cancer

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