The roles of 68 Ga-PSMA PET/CT and 18 F-FDG PET/CT imaging in patients with triple-negative breast cancer and the association of tissue PSMA and claudin 1, 4, and 7 levels with PET findings.

AIM: Aim of study is to compare the results of Gallium-68-prostate-specific membrane antigen ( 68 Ga-PSMA) and 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography(PET)/computed tomography (CT), to evaluate the correlation between PET findings and the level of PSMA, Claudin (Clau) 1, 4, and 7 receptors obtained by immunohistochemical (IHC) analysis, and to determine potential predictive and prognostic values in TNBC. METHODS: Forty-seven lesions of 42 subjects diagnosed TNBC both underwent PET/CT scan for preoperative staging/restaging were prospectively included study. PSMA, Clau 1, 4, and 7 expressions were IHC evaluated from the biopsy samples of the primary tumor (PT). Maximum standardized uptake value(SUV max) of the PT, lymph node, and distant organ metastases (DOMs) on 18 F-FDG and 68 Ga-PSMA PET/CT were compared with PSMA, Clau 1, 4, and 7 receptor expressions. RESULTS: IHC analyses on 29 BC lesions to demonstrate Clau expression showed 86% (25/29) Clau 1, 86% (25/29) Clau 4, 45% (13/29) Clau 7, and 48% (14/29) PSMA-positive. The mean DOM (SUVmax) was 15.5 ± 11.6 for 18 F-FDG and 6.0 ± 2.9 for 68 Ga-PSMA. Axial diameter of BC PT had a significant positive correlation with 18 F-FDG SUVmax, 68 Ga-PSMA SUVmax, and PSMA scores. BC lesions 68 Ga-PSMA SUVmax had a significant negative correlation with the Ki-67 index. Axial diameter of the primary tumor had significant negative correlation with Clau 7 scores ( r = -0.409, P = 0.034). Absence of Clau 1 expression found to significantly increase the rate of DOM (100% vs. 28%) ( P = 0.014). All patients with axillary lymph node (ALN) metastases ( n = 17, 100%) exhibited Clau 4 positivity ( P = 0.021). The presence of PSMA expression observed to significantly increase the rate of ALN metastases (64.7% vs. 25%) ( P = 0.035). CONCLUSION: Confirming PSMA expression with PET imaging would be significant as PSMA, a theranostic agent, may be a considerable potential agent for radionuclide treatment strategies, in addition to its additional diagnostic contribution to FDG, especially in patients with metastatic TNBC, which is an aggressive, heterogeneous disease.

68Ga PSMA Uptake at Roux-en-Y Eso-jejunostomy Junction Mimicking the Recurrence of Gastric Carcinoma in PET/CT.

A 67-year-old male patient had undergone total gastrectomy and Roux-en-Y eso-jejunostomy 3 years ago for the treatment of tubular adenocarcinoma located at the corpus of the stomach. The patient was diagnosed with Gleason score 8 (4+4) metastatic prostate cancer during the follow-up period and received hormone therapy. Owing to his elevated prostate-specific antigen levels (77 ng/mL), his clinician referred him gallium-68 (68Ga) prostate-specific membrane antigen 11 (PSMA) positron emission tomography/computed tomography (PET/CT) for restaging. PET/CT showed multiple 68Ga PSMA receptor-positive skeletal lesions and linear PSMA activity at the eso-jejunostomy junction. He was then referred to undergo 18fluorine-fluorodeoxyglucose (18F-FDG) PET/CT to screen for gastric carcinoma recurrence. PET/CT images demonstrated no 18F-FDG avid lesion. However, endoscopy and biopsy performed with samples from the eso-jejunostomy junction revealed superficial benign squamous epithelial fragments.

The association of 18F-fluorodeoxyglucose PET/computed tomography parameters with tissue gastrin-releasing peptide receptor and integrin αvß3 receptor levels in patients with breast cancer.

OBJECTIVE: Gastrin-releasing peptide receptor (GRPR) and integrin αvß3 receptors are significantly associated with primary breast cancer, neovascular endothelial, and metastatic tumor cells. We aimed to evaluate GRPR and integrin αvß3 receptor staining, F-FDG uptake patterns and possible prognostic factors in breast cancer. METHODS: Ninety lesions of 87 subjects diagnosed with breast cancer were included in this prospective study. The sections were stained with GRPR and integrin αvß3. Subjects were divided into four molecular subgroups: luminal A, luminal B, triple negative and HER2. PET/CT imaging was performed on all subjects. The groups were compared in terms of GRPR and integrin αvß3 staining properties, possible prognostic factors and mean SUVmax values. RESULTS: Increased F-FDG uptake was significantly associated with estrogen receptor and progesterone receptor negativity. Molecular subtypes were significantly associated with mean integrin scores (P = 0.030), while histopathological subtypes were significantly associated with mean GRPR scores (P = 0.029). Increased integrin αvß3 expression is significantly associated with ER and PR negativity. Additionally, GRPR score was significantly correlated with estrogen receptor and progesterone receptor expression scores and a negative statistically significant correlation was detected between integrin and progesterone receptor scores. Mean primary lesion SUVmax had a statistically significant positive correlation with integrin αvß3 score. CONCLUSION: GRPR and integrin αvß3 expression results are complementary to F-FDG PET/CT findings, and are also significantly correlated with hormone receptors associated with aggressive subtypes. These results may pave the way for GRPR and integrin αvß3 targeted imaging with Ga-labeled molecules and systemic radionuclide treatment with Lu-labeled compounds.