title: Evaluation of recurrent disease in the re-staging of colorectal cancer by18F-FDG PET/CT: Use of CEA and CA 19-9 in patient selection.
abstract: The aim of the present retrospective study was to evaluate the sensitivity and specificity of fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing the recurrence of colorectal cancer (CRC) with regard to carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9).18F-FDG PET/CT was performed in 100 patients for the re-staging of CRC. Therapy was discontinued prior to the examination. The mean (± standard deviation) CEA value (measured ~30 days prior to PET/CT examination) was 23.71 (±107) ng/ml, whereas the CA 19-9 value was 72 (±190.3) U/ml. Differences in CEA and CA 19-9 values in patients with scans that were positive or negative for recurrence were analyzed by means of a receiver operating characteristic (ROC) curve. ROC curves were used for the calculation of the sensitivity and specificity of18F-FDG PET/CT for the CEA and CA 19-9 levels. The results of the18F-FDG PET/CT were found to be associated with the CEA level (P=0.001), but not with the CA 19-9 level (P=0.43). PET/CT was positive for recurrence in 60 patients (60.0%), whose mean CEA and CA 19-9 values were 33.07±136.7 ng/ml and 75.24±192.3 U/ml, respectively. PET/CT was negative for recurrence in 40 patients (40.0%), whose mean CEA and CA 19-9 values were 10.15±30 ng/ml and 67.76±190 U/ml, respectively. On the basis of ROC curve analysis, the best compromise between sensitivity and specificity was achieved for CEA levels of 3.5 ng/ml [sensitivity, 80%; 95% confidence interval (CI), 67-89%; and specificity, 60%; 95% CI, 45-78%]. The study concluded that the detection of recurrence by18F-FDG PET/CT in patients treated for CRC is associated with CEA, but not CA 19-9 serum levels. Moreover,18F-FDG PET/CT should be recommended in patients with suspected CRC recurrence even when they present with CEA levels below the normal cut-off.
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Agostino
authors.initials: A
authors.lastname: Chiaravalloti
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fiorentini
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Palombo
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Rinino
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Lacanfora
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Danieli
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Di Russo
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Di Biagio
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Squillaci
authors.affiliation: Department of Biomedicine and Prevention, Nuclear Medicine Unit, University Tor Vergata, I-00133 Rome, Italy; Institute for Treatment and Research Neuromed, Pozzilli I-86077, Italy.
authors.forename: Orazio
authors.initials: O
authors.lastname: Schillaci
keywords: carbohydrate antigen 19–9; carcinoembryonic antigen; colorectal cancer; positron emission tomography; recurrence