[Thyroglobulin, 131I-whole body scintigraphy and risk factors in the follow-up of differentiated thyroid cancer].

Results of 131I whole body scans and measurements of thyroglobulin (Tg) in the follow-up of 85 patients with differentiated thyroid cancer were analysed in a retrospective study. All patients were assumed to be tumor-free after therapy. During follow-up, cancer recurrence was observed in 11 patients. Out of 24 131I scans performed for suspected recurrence, cancer was localized in 5. Out of 71 routinely performed 131I scans and Tg measurements during hormone withdrawal, new pathologies were observed in each of two cases one year after the last therapy. 10 out of 11 tumor recurrences were observed in a high-risk group of 40 patients with follicular histology or stage III or IV (UICC 1987). One recurrence occurred in a low-risk group of 41 patients with papillary histology and UICC stage I or II. Later than one year after therapy no recurrence was observed in any patient who belonged to the low-risk group. These results indicate that 131I scans and Tg measurements under endogenous TSH stimulation are necessary in cases of suspected recurrences and probably on a routine basis one year after the last therapy in all patients. In the event of an inconspicuous further course this diagnostic procedure should be restricted to special high-risk groups. Using a cut-off level of 5 ng/ml as compared to 10 ng/ml, the number of false-negative Tg results under suppressive therapy decreased clearly whereas that of the "false-positive" results increased less pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)