核医学と放射線治療

Role of Thyroglobulin, Neck Ultrasound, Thyroglobulin Antibodies Trend and Diagnostic Whole Body Scan in the Management of Differentiated Thyroid Cancer Patients with Persistent Thyroglobulin Antibodies

Abstract

Laura Agate, Loredana Lorusso, Paolo Piaggi, Francesca Bianchi, Federica Brozzi, Pierina Santini, Eleonora Molinaro, Paolo Vitti and Rossella Elisei

Background: During the follow-up of differentiated thyroid cancer patients, the presence of thyroglobulin antibodies makes thyroglobulin measurements unreliable. For this reason, thyroglobulin antibodies measurement and the evaluation of their titer trend are also recommended. Objective: We aimed to identify the best method among stimulated thyroglobulin, thyroglobulin antibodies titer trend, neck ultrasound and diagnostic whole body scan for detecting the presence of disease in a group of differentiated thyroid cancer patients with thyroglobulin antibodies. Patients and methods: We retrospectively reviewed the data of 212 consecutive differentiated thyroid cancer patients with thyroglobulin antibodies referred to us between 2005 and 2007 for performing a diagnostic whole body scan. All patients were evaluated during the first two years after the initial treatment. Results: Diagnostic whole body scan sensitivity and specificity in detecting persistent diseases were 70% and 72%, respectively. Diagnostic whole body scan alone had the best positive and negative predictive values (93% and 32%, respectively). A low sensitivity and specificity (56% and 10%, respectively) for increasing or stable thyroglobulin antibodies titer trends were also identified. A good compromise between sensitivity and specificity was obtained when diagnostic whole body scan, stimulated thyroglobulin and neck ultrasound were combined without considering thyroglobulin antibodies trend evaluations (82% and 45%, respectively). Conclusions: Diagnostic whole body scan plays an important role in detecting persistent disease in differentiated thyroid cancer patients with thyroglobulin antibodies, both alone and in association with other methods. However, its low negative predictive value suggests that when a suspicious persistent disease is present, the use of other imaging methods, such as computed tomography scan or FDG-positron emission computed tomography, is recommended. Finally, from this study, it appears that the thyroglobulin antibodies titer trend does not add any useful information about the disease status in the first two years after initial treatment.