Abstract 1657P
Background
At present, identification of radioiodine (RAI) refractory differentiated thyroid cancer (RAIR-DTC) is mainly based on the clinical characteristics of the lesions rather than the pathological changes. Here, we reported preliminary results of the genomic characteristics underlying RAIR-DTC.
Methods
The formalin-fixed paraffin-embedded samples of 94 patients diagnosed as DTC were sequenced in a 24-gene commercial panel (ThyroLeadTM). Microsatellite instability (MSI) was detected with the MSIsensor2 tool (MSI-H was defined as score greater than 20%). 43 of them were identified as RAIR-DTC by manual inspection according to the 2015 American Thyroid Association guidelines.
Results
Among 94 patients, 73 patients (77.7%) had distant metastases, to the lungs in 93.3%, bone in 20.6%, both sites in 16.5%, brain in 6.9%, and liver in 1.4%. Overall, a higher rate of being RAIR-DTC is associated with older age at diagnosis (p=0.0059). In consistent with previous studies, it was found that BRAF V600E (p=0.046) and TERT promoter (p =0.0017) mutation were associated with worse RAI uptake. Of 43 RAIR-DTC cases, tumor from 25 patients (58.1%) harbored BRAF V600E mutations, 16 (37.2%) had TERT promoter mutation, 6 (14.0%) had TP53 mutation and 3 (7.0%) had KRAS mutation. Concomitant BRAF V600E and TERT promoter mutations were found in 2 patients, and all of them were in the RAIR stage. Meanwhile, 29 (67.4%) of RAIR-DTC cases harbored mutations in the RAS/RAF pathway. In clinical aspects, gene fusion is related to the younger age at diagnosis (standard deviation = 14, p＜0.001), while without statistical significance in indicating RAIR-DTC. Only 1 RAIR-DTC patient had an MSI-H result, and the rest exhibited microsatellite stability.
Conclusions
Here we illustrated several factors associated with RAI uptake. Further stratification study is required to establish a more detailed profiling of RAI uptake, to reduce the overtreatment of RAIR-DTC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.