Detection Of Unknown Primary Tumours Research Articles

6. 18F-FDG Whole Body Positron Emission Tomography (PET) in the Detection of Unknown Primary Tumors

Purpose: To evaluate the utility of FDG-PET in detecting primary tumors in patients with metastatic disease from unknown primary tumors.Methods: 12 patients with metastases from unknown origin after unsuccessful conventional diagnostic procedures were studied. 5 had lymph node metastases (2 axillary, 2 cervical, 1 mediastinal), 3 multiple metastases, 1 in the lung, 1 in the cava vein, 1 in the brain and 1 in adrenal glands. Patients received 400MBq FDG intravenously, and whole body images were acquired 60 min. after injection with an ECAT EXACT HR+. PET results were compared with histological and clinical findings.Results: All but one metastatic lesion was identified by PET. Additional metastases were visualized in 4 patients. In one helped to guide biopsy for histological diagnosis. In 4/11 patients FDG-PET did not reveal lesions suspected to be primary tumor. FDG-PET identified primary tumor in 8/11 patients (breast: 2, pancreas: 2, base of tongue: 1, adrenal gland: 1, lung: 1, stomach: 1). In 4 of them (33% of total) primary tumor was confirmed either histologically or by the clinical evolution (breast: 2, lung: 1, pancreas: 1). In 1 patient FDG-PET was false positive (base of tongue). 3 patients positive FDG-PET have not yet been confirmed. FDG-PET influenced therapeutic procedures in 4 patients (33% of total). 2 underwent surgery (breast), 1 received specific chemotherapy (lung) and 1 palliative chemotherapy (pancreas).Conclusions: Our preliminary results suggest that FDG-PET is a non-invasive technique useful in the detection of unknown primary tumors, can influence in selecting appropriate therapeutic management and could guide biopsies for histologic analysis.

18F-FDG whole body positron emission tomography (PET) in patients with unknown primary tumours (UPT)

The management of patients with unknown primary tumours (UPT) often includes a large number of radiographical studies and invasive procedures, but the occult primary tumour is detected in less than 25%. In this prospective study we explored whether non-invasive whole body PET scans using FDG (18-F-fluorodeoxyglucose) are of clinical value in detection of UPT. Whole-body FDG-PET scans were performed in 20 patients following standard staging procedures according to histology. PET results were verified either histologically or by the clinical course of the disease. 11 patients had neck metastases (5 squamous cell, 5 adenocarcinomas and 1 poorly differentiated carcinoma). The remaining patients had metastases located in bone (3), bone marrow (1), brain (1), pericardium (1), skin (1), pleura (1) and chest wall (1). All metastatic lesions were visible with PET. In 13 patients PET suggested the site for the primary tumour and this was verified in 9 (45%), either histologically or by the clinical course of disease. 8 of these had primary lung cancer and 1 had carcinoma at the basis of the tongue. In most patients PET had no treatment related implications. 3 patients with non-small cell lung cancer (NSCLC) received chemotherapy prompted by the PET result. The rest received either radical radiotherapy to the head and neck region (7), palliative radiotherapy to the metastatic lesion (8), chemotherapy based on signet ring cell carcinoma in bone marrow (1) or no therapy (1). These results indicates that PET is useful in UPT preceding expensive and invasive diagnostic procedures and can result in a faster diagnosis in approximately one third of the patients who then avoid unnecessary extensive procedures. Furthermore, a larger proportion of patients will receive treatment aimed at the correct diagnosis. A prospective cost-effectiveness analysis of PET in this setting is warranted

The detection of unknown primary tumors in patients with cervical metastases by dual-head positron emission tomography.

A dilemma may occur in relation to patients with cervical metastases appearing as the first sign of malignancy in the head and neck region. In these patients, the location of the involved lymph nodes may indicate the location of the primary tumor. However, in two or three per cent of the patients, the primary tumor cannot be identified in the diagnostic workup. The aim of the present study was to investigate the possibility of identification of primary tumors in patients with cervical metastases of unknown origin, by the use of 2-(fluorine-18)fluoro-deoxy-D-glucose (FDG) dual-head positron emission tomography (PET). Ten consecutive patients with a cervical metastases of unknown origin were studied with FDG, using a dual-head PET camera. After the injection of 185 MBq (5 mCi) of FDG, images were performed of the head, neck and chest. In addition, endoscopy and biopsies were carried out with knowledge of the PET study. In patients in whom a primary tumor could not be identified, a follow-up of at least 6 months was used as a control. In five out of 10 patients a primary tumor was identified by FDG-PET. In one patient multiple sites of uptake were seen, and this was found to be consistent with non-Hodgkin lymphoma. In five patients, additional sites of increased uptake were found, these being consistent with unknown metastatic disease. Finally, in six patients, the initial treatment plan was changed due to the PET result in five of them. In one patient, the primary tumor was resected revealing a lesion with a diameter of 6 mm. The detection of FDG in patients with cervical metastases of unknown origin by the use of a dual-head PET camera is a valuable diagnostic tool in the identification of primary lesions.