Impact of 18F-FDG PET/CT for Detecting Primary Tumor Focus in Patients with Histopathologically Proven Metastasis

Authors

  • Elgin Ozkan Ankara University Medical School, Department of Nuclear Medicine, Ankara, Turkey
  • Cigdem Soydal Ankara University Medical School, Department of Nuclear Medicine
  • Mine Araz Dışkapı Yıldırım Beyazıt Training and Research Hospital, Department of Nuclear Medicine
  • N. Ozlem Kucuk Ankara University Medical School, Department of Nuclear Medicine, Ankara, Turkey

Keywords:

Cancer of unknown primary, 18F-FDG, Positron emission tomography, Therapy management, Metastases

Abstract

Purpose: To describe the impact of fluorine (18F) - fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in detecting primary tumor focus in our patient population who had histopathologically proven metastasis.

Methods: 37 patients who underwent 18F-FDG PET/CT to detect primary tumor focus in our department were included in the study. The results of PET/CT and clinical follow-up data were reviewed retrospectively. PET/CT results were compared with histological analysis and/or clinical follow-up data.

Results: Primary site of malignancy was correctly identified by PET/CT in 16 patients (16/37, 43%). Lung was the most common detected site (7/16). The mean SUV of metastatic tumor was higher than that of primary tumor. False positive and false negative results were obtained in 2 patients, respectively. In the remaining patients (17/37; 46%) the primary tumor was not localized by PET/CT. According to these results, the sensitivity and specificity of PET/CT were calculated as 89% and 90%, respectively. However, PET/CT scan determined additional metastatic focus and therapy management was changed (9/37, 24%). The primary focus was established in 4 of 8 (50%) patients with metastatic cervical adenopathy and in 12 of 29 (41%) patients with extra cervical metastases.

Conclusions: 18F-FDG PET/CT can detect the primary tumor focus in about half of all patients with histopathologically proven metastases. In the remaining patients, it may contribute to therapy management by identifying additional foci.

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Published

2016-10-14

Issue

Vol. 3 No. 2 (2016)

Section

Articles

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