Use of somatostatin receptor scintigraphy to image extrahepatic metastases of neuroendocrine tumors.

BACKGROUND: The presence of lymph node metastases significantly influences the modality of treatment in patients with liver metastases of neuroendocrine tumors (NET). Somatostatin receptor scintigraphy (Octreo-Scan, Mallinckrodt-Diagnostica, Petten, the Netherlands) is a method for localization and staging NET. The aim of our prospective study was to evaluate the effectiveness of somatostatin receptor scintigraphy in the identification of extrahepatic tumor spread.

METHODS: Thirty-five patients with liver metastases of NET were studied over a 5-year period. The presence of NET was confirmed histologically in all cases. To detect extrahepatic metastases or local tumor recurrence, conventional imaging techniques and somatostatin receptor scintigraphy were carried out.

RESULTS: In correlation with the findings of conventional imaging methods, somatostatin receptor scintigraphy confirmed liver metastases in all patients. Additionally, 19 of 35 patients (54.2%) had extrahepatic tumor lesions not detected by other imaging techniques. Of those, 15 had extensive abdominal or thoracic lymph node metastases, 3 patients had bone metastases, and in 1 patient with bronchial carcinoid local tumor recurrence was detected. All 19 patients were excluded from further evaluation for liver resection or transplantation and subjected to conservative treatment. The somatostatin receptor scintigraphy sensitivity, confirmed at the time of operation, was 91.6%. In 1 patient, in whom cluster transplantation was performed, somatostatin receptor scintigraphy failed to disclose disseminated carcinosis of the pleural cavity, detected at autopsy (false-negative rate 8.3%).

CONCLUSION: In our experience, somatostatin receptor scintigraphy provides a highly sensitive diagnostic method to localize metastases of NET. We recommend somatostatin receptor scintigraphy before liver surgery in every patient with hepatic metastases of NET to identify candidates suitable for resection.