[Use of PET-CT in pre-surgical staging of colorectal cancer hepatic metastases].

Background: Unsuspected intrahepatic and extrahepatic metastases are frequently discovered at laparotomy in patients with resectable colorectal liver metastases (CLM), and 60% of these patients will develop a recurrent tumour within 3 years, after a "curative" liver resection. These findings strongly support the need for more effective preoperative staging. The combined positron emission tomography-computed tomography technique (PET-CT) has emerged as a promising diagnostic modality for determining whether patients with recurrent disease in the liver are suitable candidates for curative resection.

Objective: The aim of this study was to assess the additional value of information provided by PET-CT compared to that of conventional radiological studies (CT and MR) in patients with resectable CLM.

Patients And Method: Between June 2006 and August 2007, 63 patients evaluated for a first resection of CLM were entered into a prospective database. Each patient received a CT-MR and a PET-CT. Forty-three patients underwent a laparotomy and 42 a hepatectomy. The main end point of the study was to assess the impact of the PET-CT findings on the therapeutic strategy.

Results: New findings in the PET-CT resulted in a change in the therapeutic strategy in 9 (14%) of the patients. However, PET-CT provided additional information was true positive by revealing abdominal extrahepatic metastases only in 4 (6.4%) patients, and falsely over-staged four patients and under staged one patient. Lesion-by-lesion sensitivity and predictive positive value for liver lesions were 78,4% and 96% for CT-MR alone, and 55% and 100% for PET-CT respectively. PET-CT was superior to CT-MR for the detection of local recurrence at the site of the initial colorectal surgery.

Conclusions: In the selection of patients with CLM being considered for surgical therapy, PET-CT provided useful information only in 6.4% of cases. Possibly longer follow-up will increase this percentage. Our findings support the use of PET-CT mainly in patients with high risk of local recurrence.