Relationship Between Tumor Burden and Serum Thyroglobulin Level in Patients with Papillary and Follicular Thyroid Carcinoma

Abstract

Serum thyroglobulin (Tg) is a reliable marker for detecting recurrent and persistent disease during the follow-up of patients with papillary and follicular thyroid carcinoma. The goal of this study was to assess the relationship between the serum Tg level measured after thyroid hormone withdrawal and the tumor mass in thyroid cancer patients who underwent surgery with the use of an intraoperative probe for lymph node metastases with (131)I uptake. Patients were classified into one of three groups according to the Tg level: undetectable (n = 18); 1-10 ng/mL (n = 21); and greater than 10 ng/mL (n = 33). The main clinical characteristics and the extent of the disease at the time of initial treatment were similar in these three groups. Lymph node metastases were found in 13 of the 18 patients with undetectable Tg level. Eight patients had persistent foci of uptake after surgery that were located behind the sterno-clavicular joint in six patients. The number of metastatic lymph nodes and their total surface (in mm(2)) or their total volume (in mm(3)) were significantly linked with serum Tg/thyrotropin [TSH] level (p = 0.002 and p < 0.0001, respectively). For a given metastatic surface or volume, the serum Tg/TSH value was no longer linked with the number of metastatic lymph nodes (p = 0.32), suggesting that the total surface or total volume is the characteristic that best summarizes the influence of the disease on the serum Tg/TSH level. In conclusion, patients with higher serum Tg levels tend to have more extensive disease and should undergo more aggressive treatment modalities. Nevertheless, undetectable serum Tg should not be considered as a reliable criteria to exclude a minimal tumor burden in patients who have already been treated with (131)I.

Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Taskforce

“…Intermediate-risk patients have microscopic invasion of tumor into the perithyroidal soft tissues at initial surgery or tumor with aggressive histology or vascular invasion (180)(181)(182). High-risk patients have macroscopic tumor invasion, incomplete tumor resection, distant metastases, or 131 I uptake outside the thyroid bed on the post-treatment scan done after thyroid remnant ablation (183,184).…”

“…The use of recovery assays for this purpose is controversial (184,198). Serial serum antithyroglobulin antibody measurements may serve as an imprecise surrogate marker of residual normal thyroid tissue or tumor (198,199).…”

“…Serial serum antithyroglobulin antibody measurements may serve as an imprecise surrogate marker of residual normal thyroid tissue or tumor (198,199). Serum thyroglobulin measurements are less sensitive in patients with small cervical lymph node metastases or less differentiated tumor (184,200). A rising unstimulated or stimulated serum thyroglobulin may indicate disease that is likely to become clinically apparent (201,202).…”

Prognostic implication of fluorine‐18 fluorodeoxyglucose positron emission tomography/computed tomography in patients with recurrent papillary thyroid cancer

“…14 Serum Tg or TgAb levels are strongly affected by the tumor volume, and the tumor burden is one of the main factors that contributes to negative 18 F-FDG PET/ CT results. 15 Many studies have shown that the possibility of obtaining positive findings on PET increases with increasing Tg levels. Schl€ uter et al 16 suggested that 18 F-FDG PET/CTpositive findings correlated positively with increasing Tg levels, and they suggested 18 F-FDG PET/CT is useful at Tg levels of 10 ng/mL.…”

Iodine Uptake Patterns on Post-ablation Whole Body Scans are Related to Elevated Serum Thyroglobulin Levels After Radioactive Iodine Therapy in Patients with Papillary Thyroid Carcinoma

“…First of all, there was no significant difference of baseline serum Tg between the two groups. Some studies suggest that pre-ablation Tg is related with remnant burden [22], although serum Tg is not actively released into blood stream in proportion to cellular burden and has limitation in estimation of small remnant burden. In addition, there is no known relationship between iodine uptake and remnant burden, although similar iodine uptake intensity suggested similar iodine accumulation [23].…”