Postoperative Radioiodine Treatment within 9 Months from Diagnosis Significantly Reduces the Risk of Relapse in Low-Risk Differentiated Thyroid Carcinoma

Abstract

PurposeAlthough postoperative radioiodine (RAI) therapy has been used in patients with differentiated thyroid carcinoma (DTC) for many years, there is still lack of data defining the timing of RAI administration. A retrospective analysis was carried out to answer the question whether the time of postoperative RAI treatment demonstrated any impact on long-term outcomes, particularly in low-risk DTC.MaterialThe analyzed group involved 701 DTC patients staged pT1b-T4N0-N1M0, who underwent total thyroidectomy and postoperative RAI therapy. According to the time interval between DTC diagnosis and RAI administration, patients were allocated to one of three groups: up to 9 months (N = 150), between 9 and 24 months (N = 323), and > 24 months (N = 228). Median follow-up was 12.1 years (1.5–15.2).ResultsBased on an initial DTC advancement and postoperative stimulated thyroglobulin concentration patients were stratified as a low-, intermediate-, and high-risk group. Low-risk patients, who received RAI therapy up to 9 months, demonstrated significantly lower risk of relapse comparing to those, in whom RAI was administered between 9 and 24 months and after 24 months since DTC diagnosis: 0%, 5.5%, and 7.1%, respectively. Regarding intermediate- and high-risk groups, the differences in the timing of postoperative RAI treatment were not significant.ConclusionIf postoperative RAI treatment is considered in low-risk DTC, any delay in RAI administration above 9 months since diagnosis may be related to poorer long-term outcomes.

The Diagnostic Role of Computed Tomography for ACR TI-RADS 4–5 Thyroid Nodules With Coarse Calcifications

“…In routine practice, the time for patients from finishing enhanced CT examination to starting RAI therapy is far more than 43 days. Moreover, the majority of studies showed that the timing of post-thyroidectomy initial RAI therapy did not affect the overall survival or long-term outcomes (33)(34)(35)(36)(37)(38). Therefore, RAI administration may be safely planned according to the logistics of the local health and the patient itself.…”

Delay of initial radioactive iodine therapy beyond 3 months has no effect on clinical responses and overall survival in patients with thyroid carcinoma: A cohort study and a meta‐analysis

“…14 Several studies have shown no difference in short clinical responses or overall survival (OS) between early and delayed RAI. [15][16][17][18] While other studies advocated that a delayed RAI may cause poor OS for DTC patients after 5 or 10 years follow-up compared with early RAI therapy, 9,21 or claimed that applying RAI therapy within 3 months could decrease ablation success. 9 Based on the above contradictory and one-sided reports, we therefore conducted a cohort study to illustrate whether early or delayed treatment of RAI affects the prognosis of DTC patients, and incorporate these results into the current body of evidence by performing a meta-analysis.…”

“… 14 Several studies have shown no difference in short clinical responses or overall survival (OS) between early and delayed RAI. 15 , 16 , 17 , 18 While other studies advocated that a delayed RAI may cause poor OS for DTC patients after 5 or 10 years follow‐up compared with early RAI therapy, 9 , 21 or claimed that applying RAI therapy within 3 months could decrease ablation success. 9 …”

Only peak thyroglobulin concentration on day 1 and 3 of rhTSH-aided RAI adjuvant treatment has prognostic implications in differentiated thyroid cancer

“…In patients with differentiated thyroid cancer (DTC), stimulated serum thyroglobulin (Tg) concentration measured around the time of radioiodine (RAI) treatment is a valuable prognostic factor for persistent/recurrent disease [1][2][3][4][5]. Given the analyte's approximately 65-h half-life, serum Tg levels should in theory drop to undetectable approximately 1 month after total thyroidectomy.…”