Effect of thyroglobulin level before ablative Radioactive Iodine on response and survival among patients with Differentiated Thyroid Carcinoma

Abstract

Background: Thyroid carcinoma is the most common endocrine malignancy, accounting for 3-4% of all cancers. Aim: This retrospective study was designed to correlate stimulated thyroglobulin (sTG) levels before treatment with radioactive iodine (RAI) and the response in patients with differentiated thyroid cancer after thyroidectomy, as well as to evaluate sTG before RAI impact on disease free survival (DFS). Patients and Methods: This study included fifty-seven patients (43 females and 32 males). who had recruited in the period between January 2015 and April 2020 with the following criteria: first operated with total thyroidectomy with confirmed pathology of differentiated thyroid carcinoma (DTC) and then treated with RAI ablation. 91.2% of the patients had papillary thyroid carcinoma (PTC) and 44 (77.2%) were early-stage T1 and T2, while 13 (22.9%) were late stage T3 and T4. Results: The post ablation TG was <1 ng/ml in 52.6%, from 1-10 ng/ml in 36.8% and >10 ng/ml in 10.5% of patients. The univariate and multivariate analyses showed disease stage and RAI dose as two independent prognostic factors of DFS. However, factors as age, gender, histopathological type, T-stage, nodal status, and sTG level were of no statistical significance to DFS. In pairwise Fisher's exact tests statistical significance difference was irrelevant between all pairs (P=0.303) comparing intermediate vs. both excellent and incomplete. Also, there was a significant difference in the baseline level of sTG between the three levels of response (P=0.05). The low levels sTG was correlated with the most excellent response, while, most incomplete response showed high level (P=0.025). Comparing the level in excellent vs. intermediate and between intermediate vs. incomplete showed no statistical significance (P=0.145 and P=0.422), respectively. Conclusion: The sTG level is associated with risk stratification in patients with DTC. sTG is considered as response-to-initial therapy predictor, recurrence, and metastasis.