Antithyroglobulin antibody as a marker of successful ablation therapy in differentiated thyroid cancer

Abstract

The aim of this study was to determine the role of antithyroglobulin antibody (ATA) serum as a marker of successful I-131 ablation therapy in differentiated thyroid cancer (DTC) patients with low serum thyroglobulin (Tg). A retrospective study was conducted on 60 patients (10 males and 50 females). All patients underwent posttotal thyroidectomy and received 2.96 to 3 GBq I-131 ablation. Subjects were divided into two groups with succesful and unsuccessful I-131 ablation therapies. The data of age, gender, histopathologic type, tumor size, and metastasis were collected. Preablation serum Tg and ATA level (Tg1 and ATA1) 6–12 months after ablation (Tg2 and ATA2) were measured. The success of ablation therapy was evaluated by diagnostic whole body scan (DxWBS) 6–12 months after ablation. There were no significant differences in age, gender, type of histopathology, tumor size, and nodal metastasis between the two groups. ATA2 ≤30 kIU/L were found in 23 (62.2%) subjects with successful ablation therapy, and ATA2 >30 kIU/L in 16 (69.6%) subjects belonged to the unsuccessful group (P = 0.017). Changes between ATA1 and ATA2 levels did not differ significantly in both the groups (P = 0.062). Tg1 <10 mg/L was found in 26 (57.8%) subjects with successful therapy (P = 0.037). Multivariate analysis showed ATA2 and Tg1 as the independent factors for the success of ablation therapy (P = 0.007 and 0.015). Adjusted odds ratio of postablation ATA was 5.379 [95% confidence interval (CI) 1.590 to 18.203] and preablation Tg was 5.822 (95% CI 1.418 to 23.902). ATA levels at 6–12 months after ablation, by considering the preablation Tg levels, is a useful marker to determine successful ablation therapy in WDTC patients with low serum Tg. Changes in serum ATA levels, although not statistically significant, can provide additional information about the course of the disease.

Clinical implications of anti-thyroglobulin antibody measurement before surgery in thyroid cancer

“…We previously reported that in DTC patients who previously had total thyroidectomy and high-dose RI remnant ablation, thyroid bed RI uptake at the postoperative 6- to 12-month whole-body scan showed a close association with higher TgAb levels, compared to no thyroid bed uptake [ 44 ]. Dewi et al [ 45 ] also reported that higher post-RI TgAb levels were significantly correlated with unsuccessful RI therapy (OR, 5.379; p = 0.007), which indicates that TgAb could serve as a surrogate marker for successful RI. We assume that the existence of TgAb represents remnant thyroid tissue, because TgAb can be detected as a response to remaining Tg.…”

Thyroglobulin/thyrotropin ratio for predicting long-term response in differentiated thyroid carcinoma: a retrospective study

“…DTC's have low lethality rates and slow indolent growth. Although 10 year survival rates are around 80%-95%, some cases have more aggressive behaviour and recurrence levels up to 35% indicating a cautious approach and long-term clinical follow-up (4)(5)(6)(7)(8). For a long time the standard treatment for these tumours was total thyroidectomy (TT) followed by iodine-131…”

“…After TT, Tg seems to reach its lowest level at around three to four weeks ( 2 ), and its levels are influenced by various factors, including the presence of anti-Tg antibodies (TgAb) ( 6 , 13 , 14 ), the remaining quantity of thyroid tissue, the presence of metastatic lesion, time since surgery, and characteristics inherent to the test used for taking measurements ( 2 , 15 ). Also, TSH level at the time of Tg measurement could have an impact on marker concentration ( 2 , 15 ).…”