¹³¹I Treatment of ¹³¹I Negative Whole Body Scan, and Positive Thyroglobulin in Differentiated Thyroid Carcinoma: What Is Being Treated?

Abstract

Several aspects of the management of differentiated thyroid cancer cause considerable controversy. Among these is the role of 131I therapy in patients after thyroidectomy. There is no controlled study to demonstrate whether this treatment reduces the recurrence rate or improves mortality. Because of the overall excellent prognosis, it is unlikely that a controlled study will ever be conducted. Most frequently, patients have a diagnostic scan with 131I to determine whether radioiodine would be an appropriate therapy and to judge much to be prescribed, based on the extent of abnormalities seen on the scintiscan. Serum thyroglobulin (Tg) has been found to be a valuable tumor marker, with very good sensitivity and specificity. In most patients, the result of whole-body 131I scintiscan and Tg measurement give concordant results. However, in some patients, Tg is measurable, but the diagnostic scan with 131 is normal. There has been data published about treatment of these patients with therapeutic doses of 131I. The author questions whether this treatment is appropriate, prompted by seeing and hearing of patients who were treated with therapeutic doses of 131I, but had no abnormal uptake of the therapeutic doses and who had no improvement in serum Tg level. These patients have no clinical evidence of disease, and the only abnormality is measurable Tg. Since large doses of radioiodine are not without problems, a controlled clinical trial should be developed to evaluate efficacy in this situation.

Outcome in patients with differentiated thyroid cancer with negative diagnostic whole-body scanning and detectable stimulated thyroglobulin

“…This is in agreement with the opinion of some experts in the field, who have raised questions concerning the approach of blind treatment (2,5,17). They argued that many of the blindly treated patients possibly have only very limited disease, which has little effect on their life expectancy.…”

“…Several studies have shown a decrease in serum Tg-off after high-dose 131 I treatment in patients with negative results from diagnostic radioiodide scanning (13,15,16). However, in other studies, serum Tg remained the same or was increased (6,17).…”

Juvenile differentiated thyroid carcinoma and the role of radioiodine in its treatment: a qualitative review

“…This situation occurs in 10-15% of DTC patients, children included, and with respect to adults, has occasioned very intense controversy (McDougall 1997, Fatourechi et al 2002, Britton et al 2003. Koh et al (2003) recently compared two non-randomized groups of adults with elevated serum Tg but no abnormal foci of 131 I uptake on diagnostic WBS, one group (n=28) given 131 I treatment and the other (n=32) untreated.…”

Significance of postoperative serum thyroglobulin levels in patients with papillary and follicular thyroid carcinomas

“…Circulatory Tg levels differed significantly between patients with different clinical classes of disease at the time of diagnosis. Of the 83 patients who presented with distant metastases, 81.9% were in group C. There would appear to be some controversy regarding appropriate treatment of patients with negative findings on 131 I scans and elevated serum Tg levels [20,21]. Is it proper to treat patients with elevated Tg levels who do not demonstrate other factors indicating poor prognosis?…”