Role of Positron Emission Tomography In Detecting Primary Site in patients with Metastatic Cancer Of Unknown primary
Abstract
Introduction:
The management of patients presenting with metastases of unknown primary origin remains a clinical challenge despite a large variety of imaging modalities. The aim of this study was to evaluate FDG PET in detecting the sites of primary cancer in these patients.
Methods:
A total of 39 patients who had known or suspected primary malignant lesions and who had undergone whole-body 18F-FDG PET in international medical center during the period of September 2004 till March 2009 were retrospectively included for analysis. All patients had undergone prior investigations with a minimum of clinical examination, biopsy and CT. Clinical, surgical, and histopathologic findings and complete correlative imaging were used to assess the results.
Results:
PET-positive lesions suggestive of primary malignant tumors were found in 28 (71.8%) of 39 patients. These lesions were pathologically proven to be malignant (TP) in 25 (64.1%), In 3 of 39 patients, PET was proven falsely positive after pathologic assessment. In 11 of 39 (28.2%) patients, no site of a primary could be detected by PET. 8 of them (20.5%) were subsequently proven True-Negative (TN), and the other 3 cases were false negative. The FDG PET sensitivity was 89.3%, with a specificity of 72.7% and accuracy in the search for the presence of a malignancy was 84.6%. Positive predictive value % (PPV) was (89.3%) and the Negative predictive Value % (NPV) was (72.72%).
Conclusion:
FDG PET is a valuable additional diagnostic tool in patients with cancer of unknown primary because it can image unknown primary tumor sites in about two third of all patients investigated. In addition, FDG PET assists in both guiding biopsies for histologic evaluation and selecting the appropriate treatment protocol for these patients.
The management of patients presenting with metastases of unknown primary origin remains a clinical challenge despite a large variety of imaging modalities. The aim of this study was to evaluate FDG PET in detecting the sites of primary cancer in these patients.
Methods:
A total of 39 patients who had known or suspected primary malignant lesions and who had undergone whole-body 18F-FDG PET in international medical center during the period of September 2004 till March 2009 were retrospectively included for analysis. All patients had undergone prior investigations with a minimum of clinical examination, biopsy and CT. Clinical, surgical, and histopathologic findings and complete correlative imaging were used to assess the results.
Results:
PET-positive lesions suggestive of primary malignant tumors were found in 28 (71.8%) of 39 patients. These lesions were pathologically proven to be malignant (TP) in 25 (64.1%), In 3 of 39 patients, PET was proven falsely positive after pathologic assessment. In 11 of 39 (28.2%) patients, no site of a primary could be detected by PET. 8 of them (20.5%) were subsequently proven True-Negative (TN), and the other 3 cases were false negative. The FDG PET sensitivity was 89.3%, with a specificity of 72.7% and accuracy in the search for the presence of a malignancy was 84.6%. Positive predictive value % (PPV) was (89.3%) and the Negative predictive Value % (NPV) was (72.72%).
Conclusion:
FDG PET is a valuable additional diagnostic tool in patients with cancer of unknown primary because it can image unknown primary tumor sites in about two third of all patients investigated. In addition, FDG PET assists in both guiding biopsies for histologic evaluation and selecting the appropriate treatment protocol for these patients.