Clinical impact of FDG-PET/CT on colorectal cancer staging and treatment strategy

Abstract

FDG-PET/CT is rarely used for initial staging of patients with colorectal cancer (CRC). Surgical resection of primary tumor and isolated metastases may result in long-term survival or presumed cure, whereas disseminated disease contraindicates operation. We analyzed a retrospective material to elucidate the potential value of FDG-PET/CT for staging of CRC. Data were retrieved from 67 consecutive patients (24-84 years) with histopathologically proven CRC who had undergone FDG-PET/CT in addition to conventional imaging for initial staging. Treatment plans before and after FDG-PET/CT were compared and patients divided as follows: (A) Patients with a change in therapy following FDG-PET/CT and (B) Patients without a change following FDG-PET/CT. Sixty-two patients had colon and five had rectal cancer. Of these, 20 (30%; CI 20.2-41.7) belonged to group A, whereas 47 (70%; CI 58.3-79.8) fell in group B. In conclusion, FDG-PET/CT changed treatment plan in 30% of cases. In ⅓ of these there was either a change from intended curative to palliative therapy or vice versa, while in the remaining ⅔ the pattern was more mixed. Thus, even in a retrospective routine material there were substantial changes in management strategy following FDG-PET/CT for staging in CRC.

Keywords: FDG-PET/CT; clinical impact; colorectal cancer; treatment strategy.

Figures

Figure 1

Colon cancer. No metastases in preoperative imaging, but during surgery tumor tissue was removed from the peritoneum. FDG-PET/CT scan was performed with regards to residual disease. MIP PET image (A) and fused axial PET/CT images (B &; C) show multiple peritoneal metastases (red arrows) and pleural metastases (green arrows).

Figure 2

Sigmoid cancer. Peroperatively suspicious lever lesions but CT equivocal with no obvious metastases. FDG-PET/CT was performed to clarify stage post-operatively. MIP PET image (A) and fused axial PET/CT images (B &; C) show multiple liver metastases (green arrows) and lung metastases (red arrows).

Figure 3

Sigmoid cancer. Suspicious liver lesion per-operatively and on pre-operative CT (red arrow). FDG-PET/CT was performed to clarify the finding. Axial CT image (A) shows the lesion in question (red arrow), and fused axial PET/CT image (B) shows no uptake (white arrow) consistent with non-malignant lesion.

Figure 4

Colon cancer. Preoperative imaging (including FDG-PET/CT) raised suspicion of liver metastases. MIP PET image (A) and fused axial PET/CT image (B) show liver metastases (black arrows), which were confirmed by surgery. FDG-PET/CT findings were consistent with conventional imaging and did not cause any change in management.