Localization of Unknown Primary Site with ⁶⁸Ga-DOTATOC PET/CT in Patients with Metastatic Neuroendocrine Tumor

Abstract

Localization of the site of the unknown primary tumor is critical for surgical treatment of patients presenting with neuroendocrine tumor (NET) with metastases. <b>Methods:</b> Forty patients with metastatic NET and unknown primary site underwent ⁶⁸Ga-DOTATOC PET/CT in a single-site prospective study. The ⁶⁸Ga-DOTATOC PET/CT was considered true-positive if the positive primary site was confirmed by histology or follow-up imaging. The scan was considered false-positive if no primary lesion was found corresponding to the ⁶⁸Ga-DOTATOC-positive site. All negative scans for primary tumor were considered false-negative. A scan was classified unconfirmed if ⁶⁸Ga-DOTATOC PET/CT suggested a primary, however, no histology was obtained and imaging follow-up was not confirmatory. <b>Results:</b> The true-positive, false-positive, false-negative, and unconfirmed rates for unknown primary tumor were 38%, 7%, 50%, and 5%, respectively. <b>Conclusion:</b>⁶⁸Ga-DOTATOC PET/CT is an effective modality in the localization of unknown primary in patients with metastatic NET.