Clinical outcomes of low and intermediate risk differentiated thyroid cancer patients treated with 30mCi for ablation or without radioactive iodine therapy

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

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.

High thyroglobulin and negative whole-body scan: no long-term benefit of empiric radioiodine therapy

PURPOSE

Around 10-27% of patients will present elevated thyroglobulin (Tg) levels and negative diagnostic whole-body scan (dxWBS) during differentiated thyroid cancer (DTC) follow-up. Empiric radioactive iodine (RAI) therapy in this context is controversial due to the lack of good quality studies in the context. The main purpose of this study is to compare long-term response to therapy status and overall survival between empiric RAI treated and untreated DTC patients.

METHODS

A retrospective study comparing differentiated thyroid cancer patients with negative diagnostic whole-body scan and elevated thyroglobulin levels submitted or not to empiric radioactive iodine therapy in a thyroid cancer referral center. The main outcome measures were ATA Response to Therapy Stratification at 6-12 months after RAI ablative dose, at 6-18 months after negative dxWBS and last follow-up visits.

RESULTS

Overall, 120 DTC patients with stimulated Tg >10 ng/ml and negative dxWBS were included in this study. Overall, 53 patients were submitted to empiric RAI and 67 were in the control group. No difference was observed in ATA Response to Therapy Stratification after RAI ablation or at the end of follow-up between groups. Also, no difference was found in terms of Tg changes response. After more than 10 years of follow-up, 17 patients died (13 from treated and 4 from untreated group).

CONCLUSIONS

Empiric RAI treatment was not associated with better long-term ATA response to therapy status or overall survival.

Radioactive Iodine Following Total Thyroidectomy Is Comparable to Lobectomy in Low/Intermediate-Risk Differentiated Thyroid Carcinoma: A Meta-Analysis

Radioactive iodine (RAI) is being increasingly used for remnants ablation of low/intermediate-risk differentiated thyroid carcinoma (DTC). Importantly, total thyroidectomy (TT) is in common use in the treatment of low-grade DTC to facilitate RAI despite the recommendations for lobectomy. Intermediate-risk DTC has been an arena of controversy (fueled by weighing the risks and benefits of RAI). This meta-analysis aimed to assess the role of RAI following TT in comparison to lobectomy in low/intermediate-risk patients with DTC. We identified 482 references through PubMed, Cochrane Library, EBSCO, and Google Scholar databases. The keywords used were “differentiated thyroid carcinoma”, “low/intermediate risk”, “radioactive iodine following total thyroidectomy”, “total thyroidectomy versus lobectomy and RAI”, “remnants ablation”, “recurrence”, “survival rate”, “tumor-specific cancer death”, “overall mortality”, and “tumor-specific mortality”. From the 67 full texts screened, only seven studies fulfilled the inclusion and exclusion criteria. The studies were from the USA, Australia, Asia, Mexico, and South America (63,268 patients included; five were retrospective and two prospective cohorts). No differences were found regarding recurrence and survival rate between TT followed by RAI and lobectomy alone. However, the current data were limited by the observational studies included, the pooling of both recurrence and survival rate, and the significant heterogeneity observed. The ongoing randomized controlled trials are awaited to resolve the issue.

Management and follow-up of differentiated thyroid cancer not submitted to radioiodine treatment: a systematic review

INTRODUCTION

The treatment of differentiated thyroid cancer (DTC) has been changing. In low (LR) and intermediate (IR) risk DTC, surgery is becoming more conservative and the usefulness of radioiodine (¹³¹I) has been questioned. An increasing number of patients are treated with lobectomy or total thyroidectomy (TTx), but without ¹³¹I. Consequently, the management and the follow-up of these patients need to be revised.

EVIDENCE ACQUISITION

We reviewed the available data about the management of these growing categories of patients. We focused on the emerging roles of the conventional tools in the follow-up [thyroglobulin (Tg), thyroglobulin antibodies (TgAb) and neck ultrasound (US)]. Moreover, we evaluated the changes in the use of levothyroxine (L-T4) therapy, and the role of the ongoing risk re-stratification.

EVIDENCE SYNTHESIS

Tg, TgAb and neck US continue to represent the cornerstone of the follow-up, however, a change in their interpretation is needed. In particular, the absolute value of Tg and TgAb lost their clinical meaning, while their trend over time acquired a greater value. At variance, the diagnostic role of neck US is becoming very relevant for the early identification of the local recurrences. In addition, L-T4 therapy should be personalized according with the type of surgery, the age of patients and their comorbidities.

CONCLUSIONS

Management of DTC treated with lobectomy or TTx but without ¹³¹I is worldwide changing. The evidences suggest that in this setting of patients with LR or IR of recurrences, a relaxed surveillance could represent the most reasonable choice.

Efficacy of Low-Dose Radioiodine Ablation in Low- and Intermediate-Risk Differentiated Thyroid Cancer: A Retrospective Comparative Analysis

(1) Background-low-dose radioiodine ablation is an accepted strategy for the treatment of low- and intermediate-risk thyroid carcinomas, although there is no international consensus. The aim of this study is to describe the clinical experience with low-dose radioiodine ablation in patients with low- and intermediate-risk thyroid cancer compared to high-dose ablation. (2) Methods-174 patients with low- and intermediate-risk thyroid cancer, 90 treated with low-dose ablation and 84 treated with high-dose ablation, were included. The primary endpoint was response to treatment one year after ablation, defined by stimulated thyroglobulin, whole body scan and ultrasound imaging. (3) Results-an excellent response rate of 79.8% in the low-dose group and 85.7% in the high-dose group was observed (p = 0.049). Stimulated thyroglobulin at the moment of ablation (p = 0.032) and positive antithyroglobulin antibodies (p < 0.001) were independent predictive factors for nonexcellent response. Young age (p = 0.023), intermediate initial recurrence risk (p < 0.001) and low-dose ablation (p = 0.004) were independent predictive factors for recurrence. (4) Conclusion-low-dose ablation seemed to be less effective than high-dose ablation, especially in those patients with positive antithyroglobulin antibodies or higher stimulated thyroglobulin levels at the moment of ablation. Low dose was associated with higher recurrence rates, and lower age and intermediate initial recurrence risk were independent risk factors for recurrence in our sample.