Importance of Postoperative Stimulated Thyroglobulin Level at the Time of¹³¹I Ablation Therapy for Differentiated Thyroid Cancer

Abstract

Background: Serum thyroglobulin detection plays an essential role during the follow-up of thyroid cancer patients treated with total/near total thyroidectomy and radioiodine ablation. The aim of this retrospective study was to evaluate the relationship between stimulated serum thyroglobulin (Tg) level at the time of high dose 131 I ablation and risk of recurrence, using a three-level classification in patients with differentiated thyroid cancer (DTC) according to the ATA guidelines. Also we investigated the relationship between postoperative stimulated Tg at the time of ablation and DxWBS results at 8-10 months thereafter. Materials and Methods: Patients with radioiodine accumulation were regarded as scan positive (scan+). If there was no relevant pathological radioiodine accumulation or minimal local accumulation in the thyroid bed region, this were regarded as scan negative (scan-) at the time of DxWBS. We classified patients in 3 groups as low, intermediate and high risk group for assessment of risk of recurrence according to the revised ATA guidelines. Also, we divided patients into 3 groups based on the stimulated serum Tg levels at the time of 131 I ablation therapy. Groups 1-3 consisted of patients who had Tg levels of ≤2 ng/ml, 2-10 ng/ml, and ≥10 ng/ml, respectively. Results: A total of 221 consecutive patients were included. In the high risk group according to the ATA guideline, while 45.5% of demonstrated Scan(+) Tg(+), 27.3% of patients demonstrated Scan(-) Tg(-); in the intermediate group, the figures were 2.3% and 90.0% while in the low risk group, they were 0.6% and 96.4%. In 9 of 11 patients with metastases (81.8%), stimulated serum Tg level at the time of radioiodine ablation therapy was over 10, however in 1 patient (9.1%) it was <2ng/mL and in one patient it was 2-10ng/mL (p=0.005). Aggressive subtypes of DTC were found in 8 of 221 patients and serum Tg levels were ≤2ng/ml in 4 of these 8. Conclusions: We conclude that TSH-stimulated serum thyroglobulin level at the time of ablation may not determine risk of recurrence. Therefore, DxWBS should be performed at 8-12 months after ablation therapy.

Factors Affecting Disease-Free Status of Differentiated Thyroid Carcinoma Patients

“…Although there was a study concluded that the stimulated serum Tg level at 1 st RAI therapy may not determine risk of recurrence (Hasbek, 2014). Our study, in agreement with some studies (Lin et al, 1998;Verburg et al, 2005), shows that stimulated serum Tg level at 1 st RAI therapy was an another independent prognostic factor for successful RAI therapy.…”

Value of the postablative thyroglobulin measurements for assessment of disease-free status in patients with differentiated thyroid cancer

“…Even after successful total thyroidectomy by applied experienced surgeons, absence of residual thyroid tissue is extremely rare. Low serum Tg levels (<2 ng/ml) predict successful ablation and remaining no residual tumor tissue after ablation;[9] however, the current study revealed that the postoperative Tg level is not related to ablation success as all patients with low and high levels achieved successful ablation that could be explained by 92% of patients are in the ATA low-risk category. Regarding the AJCC staging system, it was accurate to predict recurrence or persistence of disease in our population.…”

“…Postoperative RAI ablation is routinely used at some institutions to destroy thyroid remnant and occult foci of neoplastic cells. [9] Low serum sTg level at the time of ablation has negative predictive value for the absence of residual disease and the risk of persistent disease increases with increased sTg levels. [10] In this retrospective study, we investigated the natural course of DTC in 100 patients whose initial assessment after primary treatment (near-total thyroidectomy and RRA) revealed TSH-stimulated serum Tg levels between 0.4–170 ng/mL with complete structural response.…”

Role of ultrasound in the assessment of percutaneous laser ablation of cervical metastatic lymph nodes from thyroid carcinoma

“…Thyroglobulin (Tg) is often used to monitor the recurrence of papillary thyroid carcinoma (13,14); therefore, changes in serum Tg levels before and after PLA should also be evaluated. Increased serum Tg levels after 131 I treatment are indicative of recurrence or lymphatic metastasis (15,16). The aim of this study was to investigate and describe the use of conventional ultrasound and CEUS combined with serum Tg measurements for the assessment of PLA treatment of cervical metastatic lymph node metastases from papillary thyroid cancer.…”