Value of ¹⁸F-FDG PET-CT in surveillance of postoperative colorectal cancer patients with various carcinoembryonic antigen concentrations

Abstract

Aim: To evaluate the value of positron emission tomography (PET)/computerized tomography (CT) in surveillance of colorectal cancer (CRC) patients with different carcinoembryonic antigen (CEA) concentrations.

Methods: One hundred and six postoperative CRC patients who had suspected recurrence or metastasis and received fluorodeoxyglucose (FDG) PET/CT within one week were included in this study. The final diagnosis was confirmed by histological examination or clinical follow-up over at least six months.

Results: The sensitivity, specificity, and accuracy of FDG PET/CT were 95.2%, 82.6%, and 92.5%, and 94.8%, 81.4% and 92.8%, respectively, in the case- and lesion-based analyses. The sensitivity and accuracy of FDG PET/CT significantly differed from CT in both analyses (χ(2) = 8.186, P = 0.004; χ(2) =6.201, P = 0.013; χ(2) =13.445, P = 0.000; χ(2) =11.194, P = 0.001). In the lesion-based analysis, the sensitivity, specificity, and accuracy of FDG PET/CT in the abnormal CEA group were 97.8%, 82.6%, and 95.6%, compared with 81.3%, 80%, and 80.6% for patients with normal CEA levels. In case-based analysis, the sensitivity, specificity, and accuracy of FDG PET/CT were 97.2%, 77.8%, and 95% in abnormal CEA group. Only in lesion-based analysis, the sensitivity and accuracy of FDG PET/CT in the abnormal CEA group were significantly superior to those in the normal CEA group (χ(2) =6.432, P = 0.011; χ(2) =7.837, P = 0.005). FDG PET/CT changed the management in 45.8% of patients with positive scans.

Conclusion: FDG PET/CT showed superior diagnostic value and is an advisable option in surveillance of postoperative CRC patients with a vague diagnosis.

Keywords: Carcinoembryonic antigen; Colorectal cancer; Fluorodeoxyglucose positron emission tomography/computed tomography; Metastasis; Recurrence.

Figure 1

Positron emission tomography/computerized tomography and computerized tomography images of a 60-year-old man with rising carcinoembryonic antigen level of 32.3 ng/mL who had undergone rectal cancer resection and chemoradiotherapy 3 years ago. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) image showed a FDG-avid metastasis lesion, which is not typical in computerized tomography (CT) image. A: CT; B: ¹⁸F-FDG PET/CT.

Figure 2

A 38-year-old woman revealed normal carcinoembryonic antigen level of 2.8 ng/mL who underwent rectal cancer resection 22 mo ago. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) image displayed a lymph node but computerized tomography (CT) did not show it clearly. A: CT; B: ¹⁸F -FDG PET/CT.