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

Jolanta Krajewska; Michal Jarzab; Aleksandra Kukulska; Agnieszka Czarniecka; Jozef Roskosz; Zbigniew Puch; Zbigniew Wygoda; Ewa Paliczka-Cieslik; Aleksandra Kropinska; Aleksandra Krol; Daria Handkiewicz-Junak; Barbara Jarzab

doi:10.1007/s13139-019-00608-8

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

Nucl Med Mol Imaging. 2019 Oct;53(5):320-327. doi: 10.1007/s13139-019-00608-8. Epub 2019 Sep 5.

Affiliations

¹ Nuclear Medicine and Endocrine Oncology Department, M.Sklodowska-Curie Institute-Oncology Center, Gliwice Branch, Wybrzeze AK 15, 44-101 Gliwice, Poland.
² IIIrd Radiotherapy Clinic, M.Sklodowska-Curie Institute-Oncology Center, Gliwice Branch, Gliwice, Poland.
³ The Oncologic and Reconstructive Surgery Clinic, M.Sklodowska-Curie Institute-Oncology Center, Gliwice Branch, Gliwice, Poland.

Abstract

Purpose: Although 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.

Material: The analyzed group involved 701 DTC patients staged pT_1b-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).

Results: Based 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.

Conclusion: If 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.

Keywords: Differentiated thyroid cancer; Low-risk differentiated thyroid cancer; Radioiodine treatment; Recurrence; Relapse.