A New Dynamic Response to Therapy Assessment in Postoperative Patients With Low-Risk Differentiated Thyroid Cancer Treated Without Radioactive Iodine

Ping Dong; Li Wang; Liu Xiao; Liu Yang; Rui Huang; Lin Li

doi:10.3389/fonc.2021.764258

A New Dynamic Response to Therapy Assessment in Postoperative Patients With Low-Risk Differentiated Thyroid Cancer Treated Without Radioactive Iodine

Front Oncol. 2021 Nov 29:11:764258. doi: 10.3389/fonc.2021.764258. eCollection 2021.

Authors

Ping Dong¹, Li Wang², Liu Xiao¹, Liu Yang¹, Rui Huang¹, Lin Li¹

Affiliations

¹ Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, China.
² Department of Pancreatic Surgery, West China Hospital, Sichuan University, Chengdu, China.

Abstract

Background: Total thyroidectomy (TT) or lobectomy without radioactive iodine (RAI) is becoming a common management for patients with low-risk differentiated thyroid cancer (DTC). However, the assessment of response to therapy for these patients remains controversial. The aim of this study was to propose and validate a new dynamic evaluation strategy to assess the response to therapy in patients with low-risk DTC treated with TT or lobectomy but without RAI.

Methods: We performed a retrospective analysis of 543 adult patients with low-risk DTC who underwent TT or lobectomy without RAI therapy. Follow-up consisted of trends of serum thyroglobulin (Tg), anti-thyroglobulin antibody (TgAb) levels and neck ultrasonography (US) were conducted every 6-24 months. Response to therapy assessments were defined as excellent response, biochemical incomplete response, structural incomplete response, and indeterminate response according to the follow-up findings.

Results: At a median follow-up of 51 months (range 33-66 months), 517 (95%) had excellent response, while the other 26 had either biochemical incomplete response (an increasing trend of suppressed serum Tg levels, n=9; an increasing trend of TgAb levels, n=3) or indeterminate response (a stable or decreasing trend of suppressed serum Tg levels, but a stable positive trend of TgAb levels, n=14). No patients had structural incomplete response or no deaths related to thyroid cancer. The risk of incomplete response was significantly higher in lobectomy than in TT (p<0.001).

Conclusion: Our study proposed and validated a new dynamic response to therapy assessment depending on trends of suppressed serum Tg, TgAb levels, and neck US findings which could be an appropriate tool for postoperative follow-up in low-risk DTC patients without RAI therapy. Our findings provided further evidence to support no routine recommendation of RAI after surgery in low-risk DTC.

Keywords: differentiated thyroid cancer; low-risk; neck ultrasonography; response to therapy assessment; thyroglobulin.