Abstract
Background131-iodine (131I) administration after surgery remains a standard practice in differentiated thyroid cancer (DTC). In 2014, the American Thyroid Association presented new guidelines for the staging and management of DTC, including no systematic 131I in patients at low-risk of recurrence and a reduced 131I activity in intermediate risk.The present study aims at evaluating the rate of response to treatment following this new therapeutic management compared to our previous treatment strategy in patients with DTC of different risks of recurrence.MethodsPatients treated and followed up for DTC according to the 2014-ATA guidelines (Group 2) were compared to those treated between 2007 and 2014 (Group 1) in terms of general characteristics, risk of recurrence (based on the 2015-ATA recommendations), preparation to 131I administration, cumulative administered 131I activity and response to treatment.ResultsIn total, 136 patients were included: 78 in Group 1 and 58 in Group 2. The two groups were not statistically different in terms of clinical characteristics nor risk stratification: 42.3% in Group 1 and 31% in Group 2 were classified as low risk, 38.5 and 48.3% as intermediate risk and 19.2 and 20.7% as high risk (P = 0.38). Two patients (one in each group) with distant metastases were excluded from the analysis.Preparation to 131I administration consisted in rhTSH stimulation in 23.4% of the patients in Group 1 and 100% in Group 2 (p < 0.001).131I was administered to 46/77 patients (59.7%) in Group 1 (5 at low risk of recurrence) and 38/57 patients (66.7%) in Group 2 (0 with a low risk). Among the patients treated by 131I, median cumulative activity was significantly higher in Group 1 (3.70GBq [100 mCi] range 1.11–11.1 GBq [30–300 mCi]) than in Group 2 (1.11 GBq [30 mCi], range 1.11–7.4 GBq [30–200 mCi], P < 0.001). Complete response was found in 90.9% in Group 1 vs. 96.5% in Group 2 (P = 0.20).ConclusionsUsing the 2015-ATA evidence-based guidelines for the management of DTC, meaning no 131I administration in low-risk patients, a low activity in intermediate and even high risk patients, and a systematic use of rhTSH stimulation before 131I therapy allowed us to reduce significantly the median administered 131I activity, with a similar rate of complete therapeutic response.
Highlights
Differentiated thyroid cancer (DTC), which includes papillary and follicular cancers, comprises the vast majority (> 90%) of all thyroid cancers [1]
Radioactive 131-iodine (RAI) ablation of residual thyroid tissue after thyroidectomy remains the cornerstone of post-surgical treatment for patients with DTC
It is generally assumed that the first RAI administration after thyroidectomy is mainly aimed at destroying residual, presumably benign, remnant thyroid tissue, and at treating suspected but undetected or unknown regional or distant metastases [2]
Summary
Differentiated thyroid cancer (DTC), which includes papillary and follicular cancers, comprises the vast majority (> 90%) of all thyroid cancers [1]. Its incidence has increased over the last few decades, DTC remains a rare malignant disease with a usually good prognosis. Radioactive 131-iodine (RAI) ablation of residual thyroid tissue after thyroidectomy remains the cornerstone of post-surgical treatment for patients with DTC. In DTC, maybe more than in other, more aggressive malignancies, minimizing treatment-related morbidity and side effects, and avoiding unnecessary therapy, are issues that need to be taken into account in the therapeutic management due to the usually slow natural evolution of the disease. Because of the potential risks related to the exposure to ionizing radiation, selecting the appropriate patients as well as the optimal therapeutic protocol for successful treatment remains a challenge, requiring accurate disease staging and risk stratification [3]
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