THE ROLE OF FLUORINE-18-DEOXYGLUCOSE (FDG) POSITRON EMISSION TOMOGRAPHY (PET) WHOLE-BODY SCAN (WBS) IN THE STAGING AND FOLLOW-UP OF CANCER-PATIENTS - OUR FIRST EXPERIENCE

We report the results of FDG PET whole body scan in 75 cancer patients in whom tumor extent was defined by surgical, histological or cytolog ical findings and clinical follow-up. Twenty-five had malignant lympho mas, 24 lung carcinomas, and 26 other types of solid tumors. Twenty-th ree patients were evaluated at disease onset, before therapy, and 37 a t the moment of tumor recurrence; the remaining 15 patients were in co mplete remission after treatment and were taken as controls. Visual an d quantitative PET results were compared with conventional imaging (US , CT scan and/or MRI, and Tc99m MDP bone scan). In the 60 patients wit h active disease, PET as well as conventional imaging were able to loc ate the primary tumor in all 23 patients studied at disease onset. How ever, with regard to lymph node and distant metastases, PET provided t he same information as conventional imaging in 31 cases (51.6%), but r evealed further neoplastic foci in 29 cases (48.4%), 21 in lymph nodes and 8 at distant sites. The sensitivity of PET, in comparison with co nventional imaging, was 100% versus 100% for the detection of the prim ary tumor, 97.6% versus 55.8% for the localization of node metastases, and 100% versus 55.5% for the visualization of distant metastases. Th e specificity, calculated in the group of 15 disease-free patients, wa s 100% far PET and 86.6% for conventional imaging. The therapeutic app roach was modified in 12 patients (20%) on the basis of the PET result s. Furthermore, in 14 cases (23.3%) with advanced disease, PET provide d complete information on tumor spread, otherwise obtainable only by t aking together the results of all other diagnostic procedures. Our dat a indicate a higher accuracy of FDG PET whole body scan compared to co nventional imaging techniques in the evaluation of metastatic spread b oth at initial diagnosis and during followup, with an important impact on therapeutic decision-making. Moreover, by providing complete infor mation on tumor spread in some cases, PET can become a profitable tool in terms of cost reduction.