title: Prognostic value and clinical correlations of 18-fluorodeoxyglucose metabolism quantifiers in gastric cancer.
abstract: OBJECTIVE
  To investigate the correlations of pre-treatment positron emission tomography-computer tomography (PET-CT) metabolic quantifiers with clinical data of unstratified gastric cancer (GC) patients.
  
  
  METHODS
  Forty PET-CT scans utilising 18-fluorodeoxyglucose in patients who received no prior treatment were analysed. Analysis involved measurements of maximum and mean standardised uptake volumes (SUV), coefficient of variation (COV), metabolic tumour volumes and total lesion glycolysis of different thresholds above which the tumor volumes were identified. The threshold values were: SUV absolute value of 2.5, 30% of SUVmax, 40% of SUVmax, and liver uptake-based (marked 2.5, 30, 40 and liv, respectively). Clinical variables such as age, sex, clinical stage, performance index, weight loss, tumor histological type and grade, and CEA and CA19.9 levels were included in survival analysis. Patients received various treatment modalities appropriate to their disease stage and the outcome was defined by time to metastasis (TTM) and overall survival (OS). Clinical and metabolic parameters were evaluated by analysis of variance, receiver operating characteristics, univariate Kaplan-Meier, and multivariate Cox models. P < 0.05 was considered statistically significant.
  
  
  RESULTS
  Significant differences were observed between initially disseminated and non-disseminated patients in mean SUV (6.05 vs 4.13, P = 0.008), TLG2.5 (802 cm(3) vs 226 cm(3); P = 0.031), and TLG30 (436 cm(3) vs 247 cm(3), P = 0.018). Higher COV was associated with poor tumour differentiation (0.47 for G3 vs 0.28 for G1 and G2; P = 0.03). MTV2.5 was positively correlated to patient weight loss (< 5%, 5%-10% and > 10%: 40.4 cm(3) vs 123.6 cm(3) vs 181.8 cm(3), respectively, P = 0.003). In multivariate Cox analysis, TLG30 was prognostic for OS (HR = 1.001, 95%CI: 1.0009-1.0017; P = 0.047) for the whole group of patients. In the same model yet only including patients without initial disease dissemination TLG30 (HR = 1.009, 95%CI: 1.003-1.014; P = 0.004) and MTV2.5 (HR = 1.02, 95%CI: 1.002-1.036; P = 0.025) were prognostic for OS; for TTM TLG30 was the only significant prognostic variable (HR = 1.006, 95%CI: 1.001-1.012; P = 0.02).
  
  
  CONCLUSIONS
  PET-CT in GC may represent a valuable diagnostic and prognostic tool that requires further evaluation in highly standardised environments such as randomised clinical trials.
authors.affiliation: Kinga Grabinska, Radiotherapy and Chemotherapy I Clinic, Maria Skłodowska-Curie Memorial Institute of Oncology, Gliwice Branch, 44-100 Gliwice, Slaskie, Poland.
authors.forename: Kinga
authors.initials: K
authors.lastname: Grabinska
authors.affiliation: Kinga Grabinska, Radiotherapy and Chemotherapy I Clinic, Maria Skłodowska-Curie Memorial Institute of Oncology, Gliwice Branch, 44-100 Gliwice, Slaskie, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Pelak
authors.affiliation: Kinga Grabinska, Radiotherapy and Chemotherapy I Clinic, Maria Skłodowska-Curie Memorial Institute of Oncology, Gliwice Branch, 44-100 Gliwice, Slaskie, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Wydmanski
authors.affiliation: Kinga Grabinska, Radiotherapy and Chemotherapy I Clinic, Maria Skłodowska-Curie Memorial Institute of Oncology, Gliwice Branch, 44-100 Gliwice, Slaskie, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Tukiendorf
authors.affiliation: Kinga Grabinska, Radiotherapy and Chemotherapy I Clinic, Maria Skłodowska-Curie Memorial Institute of Oncology, Gliwice Branch, 44-100 Gliwice, Slaskie, Poland.
authors.forename: Andrea
authors.initials: A
authors.lastname: d'Amico
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D015999:Multivariate Analysis; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012372:ROC Curve; D019275:Radiopharmaceuticals / Q000378:metabolism*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000401:mortality / Q000473:pathology / Q000628:therapy; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18Fluorodeoxyglucose; Distant metastasis; Neoplasm staging; Positron-emission tomography; Stomach neoplasmas