title: F-18 FDG PET/CT in the assessment of patients with unexplained CEA rise after surgical curative resection for colorectal cancer.
abstract: OBJECTIVE
  We evaluated the role of quantitative assessment by maximum standardized uptake value (SUVmax) on F-18 fluorodeoxyglucose [F-18]FDG positron emission tomography/computed tomography (PET/CT) in stratifying colorectal cancer (CRC) patients with unexplained carcinoembryonic antigen (CEA) rise after surgical curative resection.
  
  
  METHODS
  Forty asymptomatic patients (mean age, 64 ± 12 years) with previous CRC and current serum CEA levels >5 ng/ml underwent [F-18] FDG PET/CT 13 ± 3 months after complete surgical resection. The SUVmax was registered on anastomosis and peri-anastomotic tissue lesions, if present. The patients were followed for 24 ± 9 months thereafter. Re-intervention, evidence of newly discovered distant metastases, and death were recognized as main events and constituted surrogate end points. The receiver-operator-curve (ROC) analysis was performed to estimate the optimal SUVmax cut-off to predict patients at high risk of main events. PET/CT results were then related to disease outcome (overall survival; OS).
  
  
  RESULTS
  The mean SUVmax at the anastomotic site was 6.2 ± 3 (range 2.6-15). At multivariate logistic regression analysis, the anastomotic SUVmax remained as the only significant contributor to the prediction of the events (p = 0.004; OR 1.97). The ROC analysis recognized that the optimal threshold of SUVmax to differentiate patients was 5.7. A worse OS was observed in patients presenting with a SUVmax greater than 5.7 as compared to those having lesser (median survival: 16 vs. 31 months; p = 0.002).
  
  
  CONCLUSIONS
  The quantitative assessment by SUVmax on [F-18]FDG PET/CT may be helpful in patients presenting with unexplained CEA rise after curative resection of CRC, by identifying those at risk of main events.
authors.affiliation: Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), Centro di Riferimento Oncologico di Basilicata (CROB), Rionero in Vulture, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Giacomobono
authors.forename: R
authors.initials: R
authors.lastname: Gallicchio
authors.forename: D
authors.initials: D
authors.lastname: Capacchione
authors.forename: A
authors.initials: A
authors.lastname: Nardelli
authors.forename: D
authors.initials: D
authors.lastname: Gattozzi
authors.forename: G
authors.initials: G
authors.lastname: Lettini
authors.forename: L
authors.initials: L
authors.lastname: Molinari
authors.forename: P
authors.initials: P
authors.lastname: Mainenti
authors.forename: A
authors.initials: A
authors.lastname: Cammarota
authors.forename: G
authors.initials: G
authors.lastname: Storto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002272:Carcinoembryonic Antigen / Q000097:blood*; D015179:Colorectal Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000601:surgery*; D023381:Endpoint Determination; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D049268:Positron-Emission Tomography; D012372:ROC Curve; D014057:Tomography, X-Ray Computed
chemical_list: D002272:Carcinoembryonic Antigen; D019788:Fluorodeoxyglucose F18