Ability of 18F-FDG PET/CT to diagnose recurrent colorectal cancer in patients with elevated CEA concentrations

Ann Nucl Med. 2010 Jun;24(5):395-401. doi: 10.1007/s12149-010-0372-z. Epub 2010 Apr 3.


Objective: Elevated levels of serum carcinoembryonic antigen (CEA) in patients with colorectal cancer (CRC) during follow-up suggest recurrence, which can be visualized by (18)F-FDG PET/CT. Since the magnitude of CEA elevation reflects cancer volume, the ability of PET/CT to detect recurrence in patients with only mildly elevated CEA might be limited. However, the accuracy of PET/CT in detecting recurrence associated with elevated CEA has not been fully assessed. We retrospectively evaluated the diagnostic performance of (18)F-FDG PET/CT postoperatively relative to CEA levels among patients with CRC.

Methods: We visually assessed 75 PET/CT evaluations of 57 postoperative patients with CEA >5.0 ng/ml. Tumor volumes were also determined using image analysis software. The final diagnosis was confirmed based on histopathological findings, or at least on 6 months of clinical follow-up.

Results: Two lung cancers were excluded and we finally analyzed data from 73 of the 75 PET/CT evaluations. Recurrences were diagnosed in 54 (prevalence 74%). The sensitivity and specificity of PET/CT to detect recurrence was 50/54 (93%) and 14/19 (74%), respectively. The positive and negative predictive values were 91 and 78%, respectively, and the positive and negative likelihood ratios were 3.52 and 0.10, respectively. Values for the sensitivity of PET/CT were 88 and 95%, and those for specificity were 78 and 70%, at serum CEA concentrations of 5-10 and >10 ng/ml, respectively. Serum CEA (r = 0.500, p < 0.001) significantly correlated with cancer volumes.

Conclusions: The present findings showed that (18)F-FDG PET/CT could accurately detect recurrent CRC irrespective of the elevated CEA concentration.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoembryonic Antigen / blood*
  • Colorectal Neoplasms / blood*
  • Colorectal Neoplasms / diagnosis*
  • Colorectal Neoplasms / pathology
  • Colorectal Neoplasms / surgery
  • False Negative Reactions
  • False Positive Reactions
  • Female
  • Fluorodeoxyglucose F18*
  • Humans
  • Male
  • Middle Aged
  • Positron-Emission Tomography*
  • Recurrence
  • Retrospective Studies
  • Tomography, X-Ray Computed*
  • Tumor Burden


  • Carcinoembryonic Antigen
  • Fluorodeoxyglucose F18