Prognostic Value of Thyroglobulin Serum Levels and 131I Whole-Body Scan after Initial Treatment of Low-Risk Differentiated Thyroid Cancer

Edelmiro Menéndez Torre; María Teresa López Carballo; Rosa María Rodríguez Erdozáin; Lluís Forga Llenas; María José Goñi Iriarte; Juan José Barbería Layana


Thyroid. 2004;14(4) 

In This Article


A posttherapy WBS carried out between 6 and 9 months after 131I ablation was negative in 167 patients (86.1%), while 27 patients (13.9%) showed radioiodine thyroid bed uptake. In no case did we observe uptake outside the neck region.

Tg serum levels measured at the same time as WBS in patients off levothyroxine with elevated TSH levels were undetectable (< 0.5 ng/mL) in 133 patients (68.6%) and detectable in 61 patients (31.4%). Of the latter, 39 patients showed levels between 0.5 and 10 ng/mL; and 22 had levels over 10 ng/mL.

Of the 133 patients with undetected Tg levels, 9 (6.8%), showed positive uptake at the thyroid bed after WBS, while of the 61 patients with detected Tg levels, 18 (29.5%) showed radioiodine uptake.

With the exception of two patients, all patients with positive WBS agreed to a new course of 131I between 90 and 120 mCi.

After a mean follow-up period of 7.7 ± 3.3 years, persistence or recurrence of thyroid disease was seen in 31 patients (16%) and 15 patients (7.7%) developed metastasis, while 163 patients (84%) are currently disease-free.

Observing the Tg levels off levothyroxine at the moment of initial scan ( Table 1 ), we find that recurrences during the evolution occur mainly in those patients with detectable Tg levels, independent of whether there was 131I uptake or not in the thyroid bed, and metastases were only seen in that group of patients.

Of the 124 patients with undetectable Tg levels and negative WBS, 111 (88.7%) were stage 1; 2 patients were stage 2; and 3 patients were stage 3.

During follow-up, positive WBS was found in 6 patients, (5 of whom had papillary-type thyroid cancer and 1 follicular type), with uptake exclusively in the thyroid bed and with elevated Tg serum levels in all cases but case 1 ( Table 2 ). In 4 of these patients a further course of ablative 131I was administered. At present, all cases, with or without levothyroxine treatment show undetectable Tg levels, while 131I uptake has disappeared at the thyroid bed in the 4 patients who underwent an additional course of 131I. In 118 patients, 131I-WBS remained negative and in 6 Tg levels sometimes became detectable during the follow-up period, always lower than 10 ng/mL (patients 7–12 in Table 2 ). Serum Tg levels remain actually over 2 ng/mL in only 2 patients, while metastasis was not discovered in any patient.

After a follow-up period of 7.4 ± 3.5 years (1.1–13.9), 122 patients of this group with initially undetectable Tg and negative WBS are in complete remission (98.5%).

Of the 9 patients with undetectable Tg levels and a positive WBS, 6 (66.6%) were stage 1; 1 patient (11.1 %) was stage 2; and 2 patients (22.2%) were in stage 3.

Eight patients received a new course of 131I, and one refused to undertake a further course. After a mean follow-up period of 8.1 ± 2.9 years (2.7–11.8), neither local nor distant metastasis was observed in any patient, showing undetectable Tg levels under treatment with levothyroxine. After withdrawal of levothyroxine, Tg levels were undetectable in 7 patients, while the other 2 had levels of 1.9 and 1.2 ng/mL ( Table 3 ). Only the patient who refused a new 131I treatment has persistence of thyroid bed uptake, while Tg level remains undetectable.

Of the 43 patients with detectable Tg levels and negative diagnostic 131I-WBS, 28 (65.1%) were stage 1; 7 (16.3%) were stage 2; and eight (18.6%) were stage 3. Thirty patients (69.7%) showed Tg levels between 0.5–5 ng/mL; 3 (6.9%) patients between 5–10 ng/mL, and 10 patients showed levels over 10 ng/mL.

After a mean follow-up period of 8.4 ± 3.3 years (1.1–13.7), eight patients (16.3%) showed metastases of the disease (patients 1–8 in Table 4 ). All these patients had papillary type carcinoma and seven had Tg levels over 10 ng/mL. In two patients, distant metastases were discovered, one in the lung (patient 6), and in the lung and brain in the other patient (patient 8). The last case eventually died. Six patients showed local recurrence as cervical nodes, four required surgery, with persistent Tg levels in all four cases. Even though they showed negative uptake after high-dose 131I-WBS, uptake at cervical nodes was seen in one patient with PET using [18F]fluorodeoxyglucose (FDG). The other two patients received high-dose 131I to treat residue in the neck, although one of them showed persistently high Tg levels, without any trace of metastasis through radiologic techniques including PET with FDG. Currently, of the eight patients, only the patient with an initial marginally elevated Tg levels (2 ng/mL) can be considered disease-free ( Table 4 ).

Ten patients of the other 35 showed persistently high Tg levels detected after withdrawal of levothyroxine, but no signs of disease has been detected using imaging techniques.

After 8.4 years of evolution, 26 patients in this group (60.5 %) were in complete remission but none of the patients with initial Tg levels over 10 ng/mL.

In 18 patients Tg levels were detectable and they showed thyroid bed uptake in the WBS ( Table 5 ). Of these, 4 (22.2%) were stage l; 8 (44.4%) were stage 2; and 6 (33.3%) were stage 3. Sixteen had papillary type carcinoma, while 2 were follicular.

After a mean follow-up period of 7.7 ± 3.7 years, 6 patients required a new surgical intervention, to remove nodes or due to local recurrence; one of them presented metastasis to the skin (patient 15), and was treated with local radio-therapy. One patient died after presenting with multiple distant metastasis (patient 5) and another died from an unrelated cause (patient 1), although 131I uptake was seen at mediastinum and at cervical nodes.

At present, only 6 patients (33.3%) are free of disease as shown in Table 5 .


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