This study aimed to investigate the prognostic value of volumetric parameters on 18F- fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in gastric-cancer patients, according to the expression status of c-MET (MET proto-oncogene, receptor tyrosine kinase); which was previously unclear. Therefore The study included 61 patients with advanced gastric cancer. Data on the baseline 18F-FDG PET/CT; clinical-pathological information, progression-free survival (PFS), and overall survival (OS) are collect.
The maximum standardized uptake value (SUVmax), peak SUV (SUVpeak); metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of gastric tumors in situ were measured on PET/CT. The expression status of c-MET was recorded based on immunohistochemical staining. But Associations between the parameters on PET/CT and patients’ survival outcomes are analyze in relation to expression status of c-MET. Patients with positive c-MET expression had significantly shorter PFS (11.5 vs. 17.6 months; P = 0.039) and OS (17.0 vs. 24.3 months, P = 0.043), and had gastric tumors with a larger MTV (70.8 ± 53.11 vs. 41.1 ± 52.32, P = 0.034) and TLG (428.39 ± 442.95 vs. 205.7 ± 354.40, P = 0.039), compared with those with negative c-MET expression.
However, SUVmax (9.6 ± 7.40 vs. 8.0 ± 4.91, P = 0.335) and SUVpeak (7.7 ± 5.99 vs. 6.62 ± 4.08, P = 0.438) were similar between these two patient groups. In patients with c-MET-positive tumors; MTV and TLG were independent factors in predicting patient OS after correction by distant metastasis (hazards ratio = 1.014 and 1.002, respectively; P = 0.024 and 0.027, respectively), while these associations were not significant in patients with c-MET-negative tumors. The prognosis of patients with gastric cancer remains dismal; although various treatment modalities have advanced in recent years.
Various treatment modalities
Clinically, 2-[18F] Fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) has been widely used in diagnosis, staging; restaging, therapy-response assessing, and prognosis predicting of patients with gastric cancer. Especially, the volumetric parameters; like the metabolic tumor volume (MTV) and total lesion glycolysis (TLG), have shown advantages over the commonly used maximum standardized uptake value (SUVmax) in predicting prognosis of patients with gastric cancer.
The interaction between the c-MET (MET proto-oncogene, receptor tyrosine kinase) and its ligand; hepatocyte growth factor (HGF), is commonly related to tumorigenesis. Over expression of c-MET has been report as associate with poor prognosis in patients with gastric cancer. Treatment targeting c-Met is a promising therapeutic approach for patients with c-MET-amplified gastric cancer. Indeed; phase III trials of onartuzumab and rilotumumab treatment of patients with gastric cancer overexpressing c-MET and a considerable number of phase I and phase II trials of agents targeting c-MET are ongoing . Therefore, it is necessary to develop a method that can indicate c-MET expression to stratify patients. Until now; no study has investigated the correlation between FDG uptake and c-MET expression in gastric cancer.