[Influence of FDG-PET-CT on diagnostic and treatment of colorectal cancer]

In patients with colorectal cancer (CRC), preoperative evaluation and staging should focus on techniques that might alter the preoperative or intraoperative surgical plan. The aim of this study was to evaluate the utility of FDG-PET-CT modality in the initial staging of patients with CRC in comparison with conventional staging methods and to determine its impact on therapeutic management.

One hundred and four patients with a diagnosis of CC, selected prospectively, were studied for staging using a standard procedure (CT) and FDG-PET-CT. All the patients were morphologically verificated by histology.

In 14 patients, surgery was contraindicated by FDG-PET-CT owing to the extent of disease (only 6/14 suspected by CT). FDG-PET-CT revealed four synchronous tumours. For N staging, both procedures showed a relatively high specificity but a low diagnostic accuracy (PET 60%, CT 64%) and sensitivity (PET 28%, CT 35%). For M assessment, diagnostic accuracy was 94% for FDG-PET-CT and 86% for CT. FDG-PET-CT evaluation led to modification of the therapy approach in 50% of patients with unresectable disease. FDG-PET-CT findings were important, revealing unknown disease in 19.2%, changing the staging in 13.46% and modifying the scope of surgery in 11.54% (with a change in the therapeutic approach in 17.85% of those patients with rectal cancer).

Compared with conventional techniques, FDG-PET-CT appears to be useful in pre-surgical staging of CC, revealing unsuspected disease and impacting on the treatment approach.