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Is there an added value for whole body scan combined with stimulated thyroglobulin testing for follow-up of differentiated thyroid cancer patients?

Background Whole-body scan (WBS) is indicated for selected patients in the follow-up of differentiated thyroid cancer (DTC). 
Aim The aim of this study was to evaluate the incidence of positive WBS in patients with negative stimulated thyroglobulin (sTg), to define the clinical characteristics of this group, and the association with disease outcome. Methods DTC patients who underwent surveillance with simultaneous sTg and WBS were included. Results Two hundred seventy-two patients were included. Age at diagnosis was 46.5 ± 15.2 years, 79% were female. Mean duration of follow-up was 11.6 ± 6.8 years. Patients were categorised according to stimulation test results: sTg(−)/WBS(−) in 192/272 (70.6%); sTg(+) regardless of WBS results in 33/272 (12.1%); and sTg(−)/WBS(+) in 47/272 (17.3%) subjects. sTg > 10 mg/dl was considered positive. The three groups had similar demographic and pathologic characteristics. During follow-up, additional treatment was given in 77 patients (28.3%). Twelve (4.4%) developed distant metastases; 16 patients (5.8%) died. No deaths were disease-related. There was no difference in mortality rate between categories (P = 0.182). On multivariate analysis, additional treatment was associated with male gender (P = 0.046) and positive stimulation test results, either sTg (P < 0.001) or WBS (P < 0.001). Of the 47 WBS(+)/sTg(−) patients, 7(15%) were treated due to positive WBS results, including two who underwent additional surgery. Conclusion A substantial proportion of stimulation test results were discordant. There was a significant association between WBS results and administration of additional treatment. Routine WBS had additional value for a small proportion of patients with no other evidence for disease and no indication for WBS.