The impact of PET/CT on the management of hepatic and extra hepatic metastases from gastrointestinal cancers.

PURPOSE: To investigate the efficacy of positron emission tomography/computed tomography (PET/CT) in detection and management of hepatic and extrahepatic metastases from gastrointestinal cancers. MATERIALS AND METHODS: Between February 2008 and July 2010, patients histopathologically diagnosed with gastrointestinal cancer and showing suspected metastasis on CT screening were subsequently evaluated with PET/CT. All patients were subgrouped according to histopathological origin and localization of the primary tumor. Localization of gastrointestinal cancers was further specified as lower gastrointestinal system (GIS), upper GIS, or hepato-pancreato-biliary (HPB). Both accuracy and impact of CT and PET/CT on patient management were retrospectively evaluated. RESULTS: One hundred and thirteen patients diagnosed histopathologically with gastrointestinal cancers were retrospectively evaluated. Seventy-nine patients had adenocarcinoma and 34 patients other gastrointestinal tumors. Forty-one patients were in the upper GIS group, 30 patients in the HPB group, and 42 patients in the lower GIS group. Evaluation the diagnostic performance of PET/CT for suspected metastasis according to histopathological origin of the tumor, revealed that the sensitivity of PET/CT - although statistically not different - was higher in adenocarcinomas than in non-adenocarcinomas (90% (95% CI, 0.78-0.96) vs. 71.4% (95% CI, 0.45-0.88), P=0.86). The specificity was not significantly different (85.7% (95% CI, 0.70-0.93) vs. 85% (95% CI, 0.63-0.94), P=1.00). In the overall patient group; CT was significantly more sensitive than PET/CT for detection of hepatic metastases (94.7% vs. 78.9%, P=0.042), whereas PET/CT was significantly more specific than CT (48% vs. 98.7%, P<0.001). In subgroup analysis, sensitivity was not significantly different (P>0.05) but specificity was significantly higher in PET/CT than CT (P<0.05). The specificity of PET/CT was highest in upper GIS (100%) and HPB (100%) subgroups. In the overall patient group; for detection of extrahepatic metastasis, the sensitivity of CT (75%) and PET/CT (87.5%) showed no significant difference (P=0.437). However, PET/CT was significantly more specific than CT (88.7% vs. 70.4%, P=0.007). In subgroup analysis, no significant difference was found between CT and PET/CT either in sensitivity or in specificity (P>0.05). The specificity of PET/CT was highest in the lower GIS subgroup (93%). The management of 45 patients (39.8%) was revised after PET/CT evaluation. CONCLUSIONS: PET/CT has a higher specificity than CT in detecting suspected hepatic and extrahepatic metastases of gastrointestinal cancers, and has an impact of nearly 40% on changing patient management strategies.