Poorly Differentiated Thyroid Cancer Research Articles

PD-L1 Expression Varies in Thyroid Cancer Types and Is Associated with Decreased Progression Free Survival (PFS) in Patients with Anaplastic Thyroid Cancer.

Thyroid cancer (TC) remains a significant clinical challenge worldwide, with a subset of patients facing aggressive disease progression and therapeutic resistance. Immune checkpoint inhibitors targeting programmed death-ligand 1 (PD-L1) have emerged as promising therapeutic approaches for various malignancies, yet their efficacy in TC remains uncertain. The objective of this study was to investigate PD-L1 expression in aggressive TC and its association with histological subtypes, molecular mutation, and progression-free survival. This is a retrospective study of patients with advanced TC seen in two tertiary health care centers. Included in this study were patients with advanced TC with recurrence or progression on therapy for whom tumor molecular profiling and PD-L1 status were available. Kaplan-Meier estimators were utilized to analyze the progression-free survival (PFS) between patients with PD-L1 positive and negative status in Anaplastic TC (ATC) subgroup. A total of 176 patients with advanced thyroid cancer were included (48.9% female). Of the patients, 13 had ATC, 11 Medullary TC (MTC), 81 Papillary TC Classic Variant (PTCCV), 20 Follicular TC (FTC), 8 Oncocytic TC (OTC), 10 Poorly Differentiated TC (PDTC), and 30 had the Papillary TC Follicular Variant (PTCFV). BRAF mutation was present in 41%, TERT in 30%, RAS in 19%, TP53 in 10%, and RET in 8.6% of patients. PD-L1 positivity was significantly different across different TC types and histological subtypes (p < 0.01): Patients with OTC had the highest frequency of PD-L1 positivity (71%), followed by ATC (69%), PTCCV (28.5%), and FTC (11%). Patients with MTC and PTCFV did not exhibit any PD-L1 positivity. TP53 mutation was positively associated with PD-L1 expression (21.6% vs. 7.5%, p = 0.03), and RAS mutation was negatively associated with PD-L1 expression (8.1% vs. 24.2% p = 0.04). Among patients with ATC, positive PD-L1 expression was associated with lower PFS (p = 0.002). PD-L1 expression varies across different TC types and histological subtypes and may be modulated by the mutational landscape. PD-L1 expression in ATC is associated with shorter PFS. Follow up studies are warranted to elucidate the molecular mechanism driving the observed differences in immune pathways, potentially paving the way for the development of more effective and personalized immune therapies for patients with aggressive TC.

Selenomethionine Suppress the Progression of Poorly Differentiated Thyroid Cancer via LncRNA NONMMUT014201/miR-6963-5p/Srprb Pathway.

Poorly differentiated thyroid cancer (PDTC) is a special type of thyroid cancer that threatens the life of the patients. Unfortunately, there are no effective treatments for PDTC right now, so it is urgent to search for new efficacious drugs. This experiment was designed to elucidate the effects of selenomethionine (SeMet) on PDTC in vitro and vivo. A xenograft animal model was used to assay the volume and weight of PDTC. LncRNA NOMMMUT014201 expression was detected by fluorescence in situ hybridization and Real-time quantitative PCR (qRT-PCR). In vitro experiments were carried on in WRO cells. The Cell Counting Kit-8 assay was performed to test the effect of SeMet on the proliferation of cells. And the migration and invasion of WRO cells by the wound-healing assay, Transwell migration and invasion assays. The cell apoptosis was measured by flow cytometry. In addition, genes related to proliferation, migration, invasion and apoptosis were detected through qRT-PCR and Western Blot. SeMet inhibited the proliferation, migration and invasion and promoted the apoptosis of WRO cells in a dose-dependent manner. Then vivo, SeMet significantly suppressed the volume and weight of PDTC. And SeMet downregulated the expressions of Ki67, PCNA, MMP2, MMP9 and BCL2, but upregulated that of BAX and Cleaved-Caspase 3. Moreover, SeMet upregulated the level of LncRNA NOMMMUT014201 both vivo and in vitro. In addition, repression of LncRNA NOMMMUT014201 removed the inhibition effect of SeMet on WRO cell growth significantly (p<0.05). Further investigation showed that LncRNA NOMMMUT014201 downregulated the expression of miR-6963-5p in PDTC cells, but miR-6963-5p inhibited the level of Srprb. In addition, sh-LncRNA NOMMMUT014201 enhanced the proliferation, migration and invasion but inhibited the apoptosis of WRO cells. However, inhibited miR-6963-5p or overexpressed Srprb relieved the effects of sh-LncRNA NOMMMUT014201on WRO cells. Collectively, SeMet inhibits the growth of PDTC in a dose-dependent manner through LncRNA NONMMUT014201/miR-6963-5p/Srprb signal pathway, thus suggesting that SeMet might be a potential drug for PDTC treatment.

Single-Institution Experience of Larotrectinib Therapy for Patients With NTRK Fusion-Positive Thyroid Carcinoma.

The real world efficacy and tolerabiltiy of NTRK inhibitor larotrectinib has not yet been reported in the literature although trial data has shown promising results. We report a retrospective analysis of patients with thyroid cancer harboring NTRK fusions who underwent treatment with larotrectinib. A single-institution, retrospective case series of patients with NTRK fusion-positive thyroid cancers treated with neurotrophic tyrosine receptor kinase (NTRK) inhibitors from January 1, 2007, to January 1, 2023, was performed. This study was conducted at a single academic tertiary referral center. Patients with confirmed NTRK-fusion thyroid cancer who received larotrectinib were included. Larotrectinib was administered in accordance with clinical judgment from oncology providers. The primary end point was progression-free survival (PFS). Eight patients with NTRK fusion-positive thyroid cancer treated with larotrectinib were identified: 4 with papillary thyroid cancer (PTC) (50%), 3 with poorly differentiated thyroid cancer (PDTC) (38%), and 1 with anaplastic thyroid cancer (ATC) (12%). The median PFS (mPFS) for all patients was 24.7 months (95% CI, 11.3-38.1). mPFS in PTC was higher than PDTC (34.6 months [24.7-48.7 months] vs 17.5 [7.1-21.1 months]; P = .017). The median overall survival (OS) was 43.8 months (29.8-56.8 months) overall. The single patient with ATC had a PFS and OS of 23 months. Two patients remained on treatment/alive at data cutoff, with a duration of response of 33.5 months and a median follow-up of 52 months. Patients achieved 1 complete response (12%), 6 partial responses (75%), and 1 stable disease (12%). In this single-institution cohort of patients with NTRK fusion-positive thyroid cancer, NTRK inhibition led to an mPFS of 25 months, with survival surpassing historic benchmarks for ATC and PDTC.

Brain Metastases in Differentiated Thyroid Cancer: Clinical Presentation, Diagnosis, and Management.

Background: Brain metastases (BM) are the most common intracranial neoplasms in adults and are a significant cause of morbidity and mortality. The brain is an unusual site for distant metastases of thyroid cancer; indeed, the most common sites are lungs and bones. In this narrative review, we discuss about the clinical characteristics, diagnosis, and treatment options for patients with BM from differentiated thyroid cancer (DTC). Summary: BM can be discovered before initial therapy due to symptoms, but in most patients, BM is diagnosed during follow-up because of imaging performed before starting tyrosine kinase inhibitors (TKI) or due to the onset of neurological symptoms. Older male patients with follicular thyroid cancer (FTC), poorly differentiated thyroid cancer (PDTC), and distant metastases may have an increased risk of developing BM. The gold standard for detection of BM is magnetic resonance imaging with contrast agent administration, which is superior to contrast-enhanced computed tomography. The treatment strategies for patients with BM from DTC remain controversial. Patients with poor performance status are candidates for palliative and supportive care. Neurosurgery is usually reserved for cases where symptoms persist despite medical treatment, especially in patients with favorable prognostic factors and larger lesions. It should also be considered for patients with a single BM in a surgically accessible location, particularly if the primary disease is controlled without other systemic metastases. Additionally, stereotactic radiosurgery (SRS) may be the preferred option for treating small lesions, especially those in inaccessible areas of the brain or when surgery is not advisable. Whole brain radiotherapy is less frequently used in treating these patients due to its potential side effects and the debated effectiveness. Therefore, it is typically reserved for cases involving multiple BM that are too large for SRS. TKIs are effective in patients with progressive radioiodine-refractory thyroid cancer and multiple metastases. Conclusions: Although routine screening for BM is not recommended, older male patients with FTC or PDTC and distant metastases may be at higher risk and should be carefully evaluated for BM. According to current data, patients who are suitable for neurosurgery seem to have the highest survival benefit, while SRS may be appropriate for selected patient.

Emerging Strategies in Thyroid Cancer Immunotherapy: A Comprehensive Systematic Review and Meta-Analysis of Clinical Outcomes

Introduction: The most prevalent endocrine cancer is thyroid cancer (TC), which has a low death rate despite a rising frequency. In order to assess the clinical results of novel immunotherapeutic approaches in TC, this systematic review and meta-analysis will concentrate on treatment-related adverse events (AEs), overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Methods: A thorough search was done on PubMed, Embase, and ClinicalTrials.gov, covering research published between January 2018 and December 2023. The inclusion criteria were satisfied by 14 research, including a range of TC subtypes and study methodologies.Results: The effectiveness of immunotherapy varied throughout TC subtypes. In advanced TC with PD-L1 positivity, pembrolizumab showed a 9% ORR and a 7-month PFS. In advanced/metastatic TC, camrelizumab + famitinib demonstrated ORRs of 33.3%-62.5% and 8.4-month PFS. Patients who tested positive for PD-L1 had greater responses to spartalizumab (19% ORR) in ATC. Combination treatments, such as pembrolizumab and lenvatinib, demonstrated encouraging outcomes in ATC and poorly differentiated thyroid cancer (PDTC), with 34.3% ORRs and a significant increase in PFS. With the fixed-effects model, the pooled ORR was 40.8% (95% CI, 37.2%-44.5%), and with the random-effects model, it was 33.4% (95% CI, 20.8%-48.9%). Considerable heterogeneity (I2 = 94.4%, p &lt; 0.01) demonstrated varying treatment outcomes across several immunotherapy protocols. Conclusion: Immunotherapy has promise in the treatment of advanced tuberculosis, especially aggressive forms such as ATC, especially when used in combination regimens. Subsequent investigations have to concentrate on refining combination tactics and finding biomarkers for patient selection.

Characterization of EpCAM in thyroid cancer biology by three-dimensional spheroids in vitro model

BackgroundThyroid cancer (TC) is the most common endocrine malignancy. Nowadays, undifferentiated thyroid cancers (UTCs) are still lethal, mostly due to the insurgence of therapy resistance and disease relapse. These events are believed to be caused by a subpopulation of cancer cells with stem-like phenotype and specific tumor-initiating abilities, known as tumor-initiating cells (TICs). A comprehensive understanding of how to isolate and target these cells is necessary. Here we provide insights into the role that the protein Epithelial Cell Adhesion Molecule (EpCAM), a known TICs marker for other solid tumors, may have in TC biology, thus considering EpCAM a potential marker of thyroid TICs in UTCs.MethodsThe characterization of EpCAM was accomplished through Western Blot and Immunofluorescence on patient-derived tissue samples, adherent cell cultures, and 3D sphere cultures of poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) cell lines. The frequency of tumor cells with putative tumor-initiating ability within the 3D cultures was assessed through extreme limiting dilution analysis (ELDA). EpCAM proteolytic cleavages were studied through treatments with different cleavages’ inhibitors. To evaluate the involvement of EpCAM in inducing drug resistance, Vemurafenib (PLX-4032) treatments were assessed through MTT assay.ResultsVariable EpCAM expression pattern was observed in TC tissue samples, with increased cleavage in the more UTC. We demonstrated that EpCAM is subjected to an intense cleavage process in ATC-derived 3D tumor spheres and that the 3D model faithfully mimics what was observed in patient’s samples. We also proved that the integrity of the protein appears to be crucial for the generation of 3D spheres, and its expression and cleavage in a 3D system could contribute to drug resistance in thyroid TICs.ConclusionsOur data provide novel information on the role of EpCAM expression and cleavage in the biology of thyroid TICs, and our 3D model reflects the variability of EpCAM cleavage observed in tissue samples. EpCAM evaluation could play a role in clinical decisions regarding patient therapy since its expression and cleavage may have a fundamental role in the switch to a drug-resistant phenotype of UTC cells.

Neoadjuvant Treatment of Locally Advanced Thyroid Cancer: A Preliminary Latin American Experience.

Background: Surgical resection is not always achievable in thyroid cancer patients. Neoadjuvant therapy is rarely used, but recent trends favor multikinase inhibitors or selective tyrosine kinase inhibitors. These aim to reduce tumor volume, enabling previously unfeasible surgeries. Patients and Methods: Consecutive patients with locally advanced malignant thyroid tumors who received systemic therapies with a neoadjuvant intention were included in this retrospective multicenter case series conducted in five Latin American referral centers. Primary outcomes were pre- versus postneoadjuvant response evaluations using the Response Evaluation Criteria in Solid Tumors, feasibility of surgery, and completeness of resection. Secondary outcomes were mortality and status at the last visit. Results: Twenty-seven patients were included in this analysis. Patients with unresectable differentiated thyroid cancer (DTC) or poorly differentiated thyroid cancer (PDTC) received sorafenib (n = 6) or lenvatinib (n = 12), those with medullary thyroid cancer (MTC) were treated with vandetanib (n = 5) or selpercatinib (n = 1), and those with anaplastic thyroid cancer (ATC) harboring a BRAFV600E mutation (n = 3) received dabrafenib and trametinib. The median patient age was 66 years (range 12-82), and 52% of the patients were female. In patients with PTC and PDTC, the median reduction in the diameter of the primary tumor was 25% (range 0-100%) after a median of 6 months of treatment. Surgical intervention was performed in 10 (55%) of the patients. Among these, six patients (60%) achieved R0/R1 resection status. Six patients with MTC had a median reduction in tumor diameter of 24.5% (range 1-49) after a median treatment time of 9.5 months. Only one patient receiving selpercatinib, with a tumoral reduction of 25% could undergo surgery, resulting in an R2 resection due to extensive mediastinal extension. Three patients with ATC showed a median tumor diameter reduction of 42% (range 6.7-50) after a median treatment time of 2 months. Two patients underwent surgical intervention and achieved R1 and R2 resection, respectively. Conclusions: While neoadjuvant therapy achieved tumoral responses, surgical resection was feasible in 55% of DTC, 33% of ATC, and 16% of MTC patients, with R0/R1 resection in 26% of the cohort, underscoring the need for patient selection and further research in this area.

Poorly differentiated thyroid cancer: Clinical, pathological, mutational, and outcome analysis.

Poorly differentiated thyroid cancer (PDTC) remains a challenge not only for pathologists and surgeons because of the difficulties associated with the diagnostic process and the compelling need for difficult thyroidectomy, but it is also of high clinical relevance because it is responsible for mortality in non-anaplastic follicular cell-derived thyroid cancer. Cases of PDTC within a 30-year period were reviewed by two independent pathologists. Histological features like atypical mitosis, necrosis, capsular, and vascular invasion were studied. Mutation analysis was done for BRAF, RET/PTC, RAS, and PI3KCA, and P53 was performed using immunohistochemistry. There were 39 patients with a median age of 53 years; 14 patients were more than 55 years of age. At presentation, 38.4% had compressive features and the median tumor size was 9 cm. At presentation, 67.7% had an extrathyroidal extension (ETE). R0 resection was achieved in 41%, with 12 cases resulting in a difficult thyroidectomy. Necrosis was seen in 65.7% and mitosis in 73.3% with well-differentiated components in 41%. The commonest mutation was RAS (23.1%). Survival was higher in the operable group (54.26, 95% confidence interval [CI]: 30.83-77.70 vs. 20.25, 95% CI: 0-54.07) months, respectively; however, 10-year survival was only 5% and only the tumor size and presence of mitosis were independent risk factors. PDTC presents with worrisome features like large size, ETE, and rapid growth. Aggressive surgical resection with extended/radical thyroidectomy may result in better loco-regional control and improved survival. RAS was the frequent mutation detected. It is worthwhile to identify prognostic factors that can predict the course of PDTC.

Comparative study between poorly differentiated thyroid cancer and anaplastic thyroid cancer: real-world pathological distribution, death attribution, and prognostic factor estimation.

The clinic-pathological boundary between poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) is unclear due to a wide spectrum of histopathological features and the rarity of the disease. In addition to that, with the highest mortality rate and non-standard treatment modality, the PDTC/ATC population has not been subjected to comprehensive description and comparison with the extent of histological characteristics, therapeutic response, prognostic factors, and death attribution analysis. A total of 4,947 PDTC/ATC patients from 2000 to 2018 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier survival curve estimation and Cox proportional hazard regression were applied. Overall, the 5- and 10-year DSS for PDTC were 71.9% and 68.0%, respectively, whereas the 5- and 10-year OS are 59.3% and 51.2%, respectively. The median survival time for ATC patients was 3 months with 1-year OS being 26.9% and 1-year DSS being 31.2%. During the follow-up period, 68.1% of the PDTC/ATC cohort were dead, 51.6% of which were attributed to thyroid malignancies and 16.5% to non-thyroid causes. The top three common non-thyroid causes of death were miscellaneous cancers, lower respiratory system disease, and heart disease. The histological feature of papillary thyroid cancer (PTC) was the leading pathological category for PDTC patients (51.7%), whereas 76.7% of ATC patients' pathological feature was characterized as unidentifiable. Sarcoma histological characteristics found in ATC cases suffer the highest overall mortality (vs. PTC, HR = 2.61, 95% CI 1.68-4.06, P < 0.001). Older age unidentifiable histology feature, more advanced AJCC N1b, AJCC M1, and SEER stage, tumor size larger than 5cm, and more invasive tumor extension were independent bad outcome predictors. The populational analysis of the PDTC/ATC cohort has provided reliable support for better understanding of the difference between PDTC and ATC cases and the guidance of clinical practice and further studies.

Flavopereirine exerts anti-cancer activities in various human thyroid cancer cells.

Thyroid cancer (TC) stands out as the most prevalent endocrine malignancy globally, with a steadily increasing incidence. Its clinical manifestations include enlarged thyroid nodules, dysphagia, enophthalmos, and various other symptoms. While standard treatments such as thyroidectomy and radioiodine therapy effectively manage most cases of differentiated thyroid cancers (DTC), some recurrent cases of DTC or those involving poorly differentiated thyroid cancers (PDTC) require specialized interventions. However, existing drugs primarily address symptom management without offering a curative solution. Therefore, the development of a new therapeutic agent for these challenging cases is of utmost importance. Flavopereirine, derived from Geissospermum vellosii, has demonstrated promise as a potential anti-cancer agent across various human cancers. However, its specific anti-cancer effects on human thyroid cancer (TC) have remained unclear. Therefore, this study aims to investigate the anti-cancer activity of flavopereirine in human TC. The research findings revealed that flavopereirine effectively hinders the growth of human TC cells, induces cell cycle arrest, promotes apoptosis, and modulates autophagy. Moreover, the study delved into the underlying mechanisms by which flavopereirine influenced signaling pathways. To validate these anti-cancer effects, an in vivo zebrafish model was utilized, confirming the efficacy of flavopereirine against human TC cells. In summary, this study establishes that flavopereirine exhibits notable anti-human TC activities, positioning it as a promising therapeutic candidate for the treatment of human thyroid cancer.

Characterization of the Thyroid Cancer Genomic Landscape by Plasma-Based Circulating Tumor DNA Next-Generation Sequencing.

Background: The limited availability of targeted therapies in thyroid cancer (TC) has challenged conventional treatment algorithms and has established urgency for the identification of targetable genomic abnormalities. In addition to widely adopted tissue-based next-generation sequencing (NGS), plasma-based circulating tumor DNA (ctDNA) NGS is rapidly emerging as a genomic biomarker detection method and is steadily gaining utility across solid tumors. To date, plasma-based genomic alterations in TC have not been determined. Herein, we profile potential actionable mutations detected through ctDNA in patients with TC subtypes. Methods: A retrospective data analysis of the Guardant Health, Inc. database was performed using the commercially available Guardant360® plasma-NGS test on TC samples from adult patients collected between 2016 and 2021. The landscape of genomic alterations and blood tumor mutation burden (bTMB) were analyzed in patients with different types of TC: anaplastic TC (ATC), papillary TC (PTC), follicular TC (FTC), oncolytic carcinoma of the thyroid (OCA), poorly differentiated TC (PDTC), medullary TC (MTC), and TC not otherwise specified (TC NOS). Results: Of the 1094 patients included most of the patients n = 876 had TC NOS, and 20% had a specific diagnosis (92 ATC, 62 PTC, 14 FTC, 16 OCA, 2 PDTC, and 32 MTC patients). The median age was 65 (range 10-98) and 47.3% were male. 78.3% of patients had one or more genomic alteration detected by ctDNA NGS. TP53 (46.9%) was the most common mutation detected among all TC. BRAFV600E was detected in 27.2% of ATC, 35.7% of PTC, and in none of FTC. RAS was detected in 18.5% of ATC, 11.9% of PTC, and 62.5% of FTC. RET, ALK, and NTRK fusions were seen in 1.1%, 0.5%, and 0.2% of all TC, respectively. RET mutations were detected in 66.7% of MTC. bTMB analysis was performed on 159 patients. The mean bTMB was higher in ATC compared with other types of TC (p = 0.0011, 0.0557, and <0.0001, respectively). Conclusions: Plasma-based comprehensive NGS is a promising NGS method in TC; however, future validation of the clinical utility by analysis of paired tumor and plasma samples is needed.

Brusatol attenuated proliferation and invasion induced by KRAS in differentiated thyroid cancer through inhibiting Nrf2.

Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) can be developed from differentiated thyroid cancer, and this dedifferentiated transformation leads to poor prognosis and high mortality. The role of Nrf2 in the dedifferentiation of differentiated thyroid cancer (DTC) induced by KRAS remains unclear. In this study, two DTC cell lines, BCPAP and WRO, were used to evaluate the function of Nrf2 in the dedifferentiation caused by wild-type KRAS (KRAS-WT) and G12V point mutation KRAS (KRAS-G12V). The overexpression of KRAS-WT and KRAS-G12V increased the proliferative and invasive ability of BCPAP and WRO cells. Aggressive morphology was observed in KRAS-WT and KRAS-G12V overexpressed WRO cells. These results suggested that overexpression of KRAS-WT or KRAS-G12V may induce dedifferentiation in DTC cells. The expression of Nrf2 was increased by KRAS-WT and KRAS-G12V in DTC cells. In addition, compared with normal thyroid tissues, the expression of Nrf2 protein was considerably higher in thyroid cancer tissues on immunohistochemistry (IHC) staining, and the increased expression of Nrf2 indicated a poor prognosis of thyroid cancer. These results indicated that Nrf2 is the KRAS downstream molecule in thyroid cancer. Functional studies showed that the Nrf2 inhibitor Brusatol counteracted the proliferative and invasive abilities induced by KRAS-WT and KRAS-G12V in BCPAP and WRO cells. In addition, the xenograft assay further confirmed that Brusatol inhibits tumor growth induced by KRAS-WT and KRAS-G12V. Collectively, this study suggests that Nrf2 could be a promising therapeutic target in KRAS-mediated dedifferentiation of thyroid cancer.

SAT534 A Rare Case of Poorly Differentiated Thyroid Cancer With Extraordinary Limitations to Treatment

Abstract Disclosure: N. Shahid: None. L. Rudman: None. H. Maldonado Rivera: None. J. Chambi-Torres: None. J.A. Gonzalez: None. S. Valepu: None. A. Barco: None. N.H. Shaaban: None. E. Angueira: None. Background: Poorly differentiated thyroid cancer (PDTC) is a rare and aggressive form of follicular epithelial cell derived thyroid carcinoma, representing 3-5% of all thyroid cancers. As a subtype, PDTC is in a category that is between well differentiated thyrocyte malignancies and undifferentiated (anaplastic) thyroid carcinomas. Current guidelines for treatment of PDTC are not well defined. Case presentation: A 56-year-old male with a history of PDTC was admitted to the hospital directly from a correctional facility due to concern for metastasis. Patient had a total thyroidectomy performed just two months ago that revealed PDTC on surgical pathology. Recommendations at that time were to complete a full body PET-CT and follow up with radiation oncology for radiation and chemotherapy. Patient was also discharged on Synthroid 175 mcg daily for TSH suppression. However, the patient did not have any follow up appointments scheduled while at the facility. PET-CT showed stable FDG avid 2.4 cm lower right neck mass and 2 cm focus of mildly increased activity in the right lobe of the liver. On admission, a triple phase MRI liver protocol was ordered and showed a 15 mm hepatic lesion that was arterially enhancing with persistent enhancement in venous and delayed phase without dropping signal on T2 fat and additional hyperintensity on T2. Bilateral 1.7 cm adrenal nodule was also identified with relative hypointensity on T2. FNA of right neck mass was performed but did not yield sufficient tissue for pathology. Subsequent right neck exploration and skin biopsies were obtained and revealed benign fibroadipose tissue with focal fat necrosis in the thyroid and lobular capillary hemangioma in right back, left chest, and right abdomen. Patient’s status as an inmate continued to delay radiation and chemotherapy for PDTC with possible metastasis. The decision was made with the hematology/oncology inpatient consult team to perform RAI treatment with 138 mCI of I-131. Synthroid was held in anticipation of the RAI and whole body scan was ordered for 1 week after administration of I-131. Post ablation whole body scan showed intense radiotracer uptake over the region of the left and right thyroid glands and normal uptake in the stomach, small bowel, and urinary bladder. No other areas of radiotracer uptake were found. Conclusion: Diagnosis and treatment of PDTC is challenging and the social constraints as an inmate make it even more difficult to initiate appropriate therapy with radiation oncology follow up. Our case illustrates the implications of RAI ablation after total thyroidectomy in staging and therapy of PDTC. Given the intermediate histologic characteristics of PDTC, further investigation is required in the setting of metastasis and exploration of the benefits of early aggressive therapy, such as external beam radiotherapy. Presentation Date: Saturday, June 17, 2023

THU484 Distinct Genetic Characteristics In Follicular Thyroid Cancer With Different Metastatic Potentials

Abstract Disclosure: S. Kwak: None. E. Lee: None. Y. Park: None. Although most follicular thyroid cancers (FTCs) show excellent prognosis, more than 5% accompany distant metastasis, often diagnosed unexpectedly in the advanced stage. Genetic or genomic markers have been shown to be useful as a prognostic tool in many cancers, but it is unclear whether genetic markers predicting the metastatic potential of FTCs exist. To investigate, 11 pairs of matched formalin fixed paraffin embedded tissue samples of primary (PTM1) and metastatic tumors (MT) from FTC patients with distant metastasis were analyzed by whole exome sequencing. For validation, 78 unmatched FTC samples including 49 well-differentiated tumors, 15 poorly-differentiated tumors and 14 anaplastic thyroid cancer (ATC) samples were analyzed by targeted sequencing. Among the 11 paired PTM1 and MT tumors, 10 showed concordant driver mutations (NRAS, HRAS, DICER1, EIF1AX), and the TERT promoter mutation was concordantly found in 6 pairs. However, the concordance rate of other somatic mutations in paired samples were found to be only 16.2%. Other mutational characteristics such as mutational signatures and CNVs also differed, suggesting the independent subclonal evolution of the paired MT from the PTM1 after metastasis. Interestingly, the frequency of mutations including driver, TERT promoter, and other mutations was lower in primary tumors without metastases (PTM0). Mutational characteristics of PTM0 also differed from those of PTM1 and MT, suggesting that the mutational or molecular characteristics of PTs at the time of diagnosis may distinguish metastatic potential. In a pooled analysis including published data of follicular patterned tumors, we found that metastatic or aggressive tumors were more likely to have the RAS mutation, which tended to be coupled with TERT, DICER1, EIF1AX, and TP53, gradually from minimally invasive FTC, widely invasive FTC to poorly differentiated thyroid cancer (PDTC) and ATC. Transcriptomic profiles from The Cancer Genome Atlas (TCGA) and our data (SNUH) showed RAS(+)/TERT(+) mutated tumors and RAS(+)/TERT(-) tumors had differences in several intracellular signal pathways. Therefore, when follicular neoplasm is diagnosed, NRAS and HRAS mutation tests followed by TERT promoter mutation tests may help diagnose FTCs with metastatic potential. Other genetic mutations could be candidates for a diagnostic or prognostic marker, and large-scale validation studies are warranted.This study was funded by the Basic Science Research Program through the National Research Foundation of Korea, funded by the Ministry of Science, ICT &amp; Future Planning (NRF-2019R1A2C2084332). Presentation: Thursday, June 15, 2023

The Frequency of Differentiated Thyroid Cancer Recurrence in 2302 Patients With Excellent Response to Primary Therapy.

Discrepant data on the recurrence rate of differentiated thyroid cancer (DTC) are reported. To evaluate the frequency and risk factors of true recurrence in DTC patients with excellent responses (ExR) to initial therapy. A retrospective analysis of the 2302 consecutive DTC patients with ExR to primary therapy, treated during 24 years at single center. The percentage of recurrence and cumulative recurrence rate (CRR) were analyzed. Risk factors for recurrence for patients with papillary thyroid cancer (PTC) were investigated and methods for establishing a diagnosis of recurrence were evaluated. Of DTC patients, 32 (1.4%) experienced recurrence. PTC patients with recurrence were more likely to have younger age (P = .0182), larger tumor size (P = .0013), lymph node metastases (P = .0013), incomplete resection (P = .0446), higher ATA risk (P = .0002), and had more frequently been treated with 131I (P = .0203). CRRs at 5, 10, 15, 20, and 24 years after surgery were 1.2%, 1.9%, 2.5%, 2.9%, and 2.9%, respectively. The CRRs according to histological type were highest for poorly differentiated thyroid cancer (PDTC), lower for oncocytic (OTC) and follicular thyroid cancer (FTC), and lowest for PTC. Most recurrences occurred within the first 5 years of observation. The most effective method for detecting local recurrence was ultrasonography with fine needle aspiration cytology, and for distant metastases, 18F-FDG PET. True recurrence is rare in DTC patients. PTC patients with ExR to primary therapy and N0/Nx can be dismissed from oncological follow-up. Despite ExR to primary therapy, DTC patients with N1, and PDTC, OTC, FTC should remain under oncological follow-up.

Neutrophil-to-Lymphocyte Ratio Is Associated With the Proportion of Poorly Differentiated Components in Papillary Thyroid Carcinoma

IntroductionDiagnosis of poorly differentiated thyroid cancer (PDTC) requires ≥ 50% of poorly differentiated components (PDC) in Japan. However, the optimal cutoff percentage of PDC for PDTC diagnosis remains controversial. Although high neutrophil-to-lymphocyte ratio (NLR) correlates with the aggressiveness of papillary thyroid cancer (PTC), whether NLR is associated with the proportion of PDC in PTC remains unstudied. Materials and methodsPatients with the pure PTC (n = 664), PTC with < 50% PDC (n = 19), or PTC with ≥ 50% PDC (n = 26) who underwent surgery were retrospectively analyzed. Twelve-year disease-specific survival and preoperative NLR were compared among these groups. ResultsTwenty seven patients died from thyroid cancer. The PTC with ≥ 50% PDC group (80.7%) showed significantly worse 12-year disease-specific survival than the pure PTC group (97.2%) (P < 0.001); however, the < 50% PDC group (94.7%) did not (P = 0.91). The PTC with ≥ 50% PDC group had a significantly higher NLR than the pure PTC (P < 0.001) and the PTC with < 50% PDC groups (P < 0.001), whereas there was no significant difference in the NLR between the pure PTC and the PTC with < 50% PDC groups (P = 0.48). ConclusionsPTC with ≥ 50% PDC is more aggressive than either pure PTC or PTC with < 50% PDC, and NLR potentially reflects the PDC proportion. These results support the validity of 50% PDC as a cut-off for PDTC diagnosis and indicate the utility of NLR as a biomarker for PDC proportion.

Effect of postoperative radiotherapy for patients with differentiated thyroid cancer.

We evaluated the efficacy and safety of postoperative radiotherapy (PORT) for differentiated thyroid cancer (DTC) with high risk features. This retrospective study analyzed 187 patients treated for DTC from 1985 to 2019. DTC referred to nonanaplastic thyroid cancer originating from follicular cells. PORT was defined as the administration of external beam radiation to the thyroid and regional lymph nodes following surgery for initially diagnosed DTC. The patients were included in the analysis if they received PORT or exhibited any of the following features: (a) pT4 or pN1b according to the 8th American Joint Committee on Cancer, (b) poorly differentiated thyroid cancer (PDTC), or (c) unfavourable variants such as anaplastic foci and etc. After 1:1 propensity matching, a total of 108 patients were analyzed according to PORT receipt. The median follow-up duration of the matched group was 10.4 years. After matching, most of the variables became balanced, but the PORT group still had more PDTC and DTC with anaplastic foci. Radioactive iodine (RAI) was less frequently administered in the PORT group. PORT yielded a significantly higher 5-year locoregional recurrence free survival (LRFS) than the No PORT group (5-year LRFS 86.1% vs. 72.7%, p = 0.022), but the 10-year cancer specific survival (CSS) was similar between them (97.8% vs. 85.9%, p = 0.122). The multivariable analysis indicated that PORT was a favourable prognostic factor (Hazard ratio 0.3, 95% Confidence interval 0.1-0.8, p = 0.02) for LRFS, but not for CSS. Among 133 patients without PORT for initial disease, 39 of them received salvage surgery followed by salvage PORT. No severe toxicity after PORT was reported. PORT reduced locoregional recurrence in DTC patients without severe toxicity. PORT can be an effective and safe treatment to improve locoregional control in DTC with high risk features. However, further study is warranted to identify those who can benefit from PORT.

Molecular features of aggressive thyroid cancer.

Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) have a worse prognosis with respect to well differentiated TC, and the loss of the capability of up-taking 131I is one of the main features characterizing aggressive TC. The knowledge of the genomic landscape of TC can help clinicians to discover the responsible alterations underlying more advance diseases and to address more tailored therapy. In fact, to date, the antiangiogenic multi-targeted kinase inhibitor (aaMKIs) sorafenib, lenvatinib, and cabozantinib, have been approved for the therapy of aggressive radioiodine (RAI)-resistant papillary TC (PTC) or follicular TC (FTC). Several other compounds, including immunotherapies, have been introduced and, in part, approved for the treatment of TC harboring specific mutations. For example, selpercatinib and pralsetinib inhibit mutant RET in medullary thyroid cancer but they can also block the RET fusion proteins-mediated signaling found in PTC. Entrectinib and larotrectinib, can be used in patients with progressive RAI-resistant TC harboring TRK fusion proteins. In addition FDA authorized the association of dabrafenib (BRAFV600E inhibitor) and trametinib (MEK inhibitor) for the treatment of BRAFV600E-mutated ATC. These drugs not only can limit the cancer spread, but in some circumstance they are able to induce the re-differentiation of aggressive tumors, which can be again submitted to new attempts of RAI therapy. In this review we explore the current knowledge on the genetic landscape of TC and its implication on the development of new precise therapeutic strategies.

Newly proposed survival staging system for poorly differentiated thyroid cancer: a SEER-based study.

Despite the recent release of the 8th edition TNM staging system, the risk stratification for poorly differentiated thyroid cancer (PDTC) remains controversial. Retrospective study. SEER database and the First Hospital of China Medical University (FHCMU) database. Between 2004 and 2015, 1201 PDTC patients from the SEER database were enrolled to propose a new staging system. 38 PDTC patients were included from the FHCMU. A retrospective analysis of 1201 PDTC cases was performed, and a new staging classification was developed as follows: stage I: age < 55 and T1/any N/M0 (n = 127, 10.57%); stage II: age < 55 and T2-4/any N/M0 or age ≥ 55 and T1-2/any N/M0 (n = 523, 43.55%); stage III: age < 55 and any T/N0/M1 or age ≥ 55 and any T3/any N/M0 (n = 239, 19.90%); stage IV: age < 55 and any T/N1/M1 or age ≥ 55 and T4/any N/M0, and T/any N/M1 (n = 312, 25.98%). The 10-year disease-specific survival rates of patients in the new stages I, II, III, and IV were 97.9%, 77.9%, 35.3%, and 12.1%, respectively. The proportion of variation explained (PVE) for disease-specific survival of the proposed system was higher than that of the 8th AJCC TNM staging (30.61% vs. 27.15%). The accuracy of the staging system was verified in 38 PDTC patients from the FHCMU. The proposed staging system provided a more accurate risk stratification for PDTC patients. The new staging model may facilitate the design of personalized treatment strategies for PDTC patients.

MMP1 acts as a potential regulator of tumor progression and dedifferentiation in papillary thyroid cancer.

Papillary thyroid cancer (PTC) is one of the malignancies with an excellent prognosis. However, in PTC, progression or dedifferentiation into poorly differentiated thyroid cancer (PDTC) or anaplastic thyroid cancer (ATC) extremely jeopardizes patients' prognosis. MMP1 is a zinc-dependent endopeptidase, and its role in PTC progression and dedifferentiation is unclear. In this study, transcriptome data of PDTC/ATC and PTC from the Gene Expression Omnibus and The Cancer Genome Atlas databases were utilized to perform an integrated analysis of MMP1 as a potential regulator of tumor progression and dedifferentiation in PTC. Both bulk and single-cell RNA-sequencing data confirmed the high expression of MMP1 in ATC tissues and cells, and further study verified that MMP1 possessed good diagnostic and prognostic value in PTC and PDTC/ATC. Up-regulated MMP1 was found to be positively related to more aggressive clinical characteristics, worse survival, extracellular matrix-related pathways, oncogenic immune microenvironment, more mutations, higher stemness, and more dedifferentiation of PTC. Meanwhile, in vitro experiments verified the high level of MMP1 in PDTC/ATC cell lines, and MMP1 knockdown and its inhibitor triolein could both inhibit the cell viability of PTC and PDTC/ATC. In conclusion, our findings suggest that MMP1 is a potential regulator of tumor progression and dedifferentiation in PTC, and might become a novel therapeutic target for PTC, especially for more aggressive PDTC and ATC.