The frequency of mutations in advanced thyroid cancer in Japan: a single-center study.

We analyzed the outcomes of genetic testing to study the frequency of mutations in advanced thyroid cancer in Japan. Patients (n = 96) with unresectable or metastatic thyroid carcinoma were included for retrospective chart review. Results of gene panel testing, which was performed between May 2020 and April 2023, were analyzed. The median age of the patients was 73.5 years (range, 17-88); 59 were women, and 39 were men. Overall, 17 patients had anaplastic thyroid carcinoma (ATC), 68 had papillary thyroid carcinoma (PTC), 7 had follicular thyroid carcinoma, and 6 had poorly differentiated thyroid carcinoma (PDTC). Of the 81 patients with differentiated thyroid carcinoma (DTC) and PDTC, 88.9% were radioactive iodine-refractory, and 32.7% of all cases had previously been treated with multiple kinase inhibitors. Of ATC cases, 52.9% had BRAF mutations, and 5.9% had RET fusion. Of PTC cases, 83.1% had BRAF mutations, 9.2% had RET fusion, and 1.5% had NTRK fusion. One case each of ATC and PTC had a tumor mutation burden of ≥10. ATC cases had a significantly higher prevalence of TP53 alterations than the other cases (82.3% vs. 11.8%), whereas the frequencies of TERT promoter mutations were 88.2% in ATC cases and 64.7% in the other cases, albeit without a significant difference. In conclusion, 58.8% of ATC, 93.8% of PTC, and 42.9% of PDTC had genetic alterations linked to therapeutic agents. Active gene panel testing is required to increase treatment options.

Histological findings of thyroid cancer after lenvatinib therapy.

AIMS: Lenvatinib is a multikinase inhibitor used for treating unresectable or metastatic cancers, including thyroid cancer. As total thyroidectomy followed by radioactive iodine therapy is a commonly recommended initial treatment for thyroid cancer, histological findings of the thyroid after lenvatinib therapy remain unclear. Therefore, the aim of this study was to analyse in-vivo changes in patients who underwent thyroidectomy after lenvatinib therapy. METHODS AND RESULTS: We screened 167 patients with thyroid cancer [papillary thyroid cancer (PTC), n = 102; follicular thyroid cancer (FTC), n = 26; anaplastic thyroid cancer (ATC), n = 39] who underwent lenvatinib therapy. Among these patients, six underwent thyroidectomy (lenvatinib-treated group: PTC, n = 3; FTC, n = 1; ATC, n = 2), and the specimens were examined. Five patients with PTC who did not receive lenvatinib therapy were included for comparison (untreated group). Microvessel density (MVD) was evaluated in both groups. The PTC and FTC specimens showed relatively more ischaemic changes than ATC specimens. Coagulative necrosis and ischaemic changes in cancer cells were frequently observed. ATC specimens showed fibrosis and mild cell damage. As hypothyroidism is a common side effect of lenvatinib therapy, non-cancerous thyroid tissues were also examined. Histological findings included mild lymphocytic infiltration, lymphoid follicular formation, histiocytic reaction and follicular epithelial destruction. The MVD in lenvatinib-treated tissues was significantly lower than that in untreated tissues. CONCLUSIONS: Lenvatinib therapy probably induces relatively specific ischaemic changes in thyroid cancer cells. Moreover, inflammatory cell infiltration and decreased MVD occur to varying degrees in non-cancerous thyroid tissue and may be related to hypothyroidism, a side effect of lenvatinib.

Membrane type 1 matrix metalloproteinase regulates anaplastic thyroid carcinoma cell growth and invasion into the collagen matrix.

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive cancer types; however, the molecular mechanism contributing to the aggressive characteristics remain unclear. Membrane type 1 matrix metalloproteinase (MT1-MMP) plays an important role in cancer invasion and has been associated with a poor prognosis in various malignant neoplasms. In this study, we investigated the relationship between MT1-MMP expression and the proliferation and invasion of ATC cells, along with the association with clinicopathologic factors in patients with ATC. Suppression of MT1-MMP reduced the proliferation and invasion of ATC cells, and suppressed ERK activity, indicating a role in cancer cell proliferation in collagen matrix culture conditions. The expression of MT1-MMP was detected in 29 of 34 (85.3%) surgical specimens from ATC patients. In addition, the expression of MT1-MMP in the tumor lesion was higher than that of normal and stromal tissues. Collectively, these results suggest that elevated MT1-MMP expression plays a role in the pathogenesis of ATC, which may promote its aggressive characteristics such as proliferation and invasion, highlighting a potential new therapeutic target.

[Clinical Outcomes of Palliative Radiation Therapy for Gastric Cancer Bleeding].

Only a few studies have been conducted regarding the palliative radiation therapy(RT)for gastric cancer(GC)bleeding. Data of 9 patients with gastric cancer requiring blood transfusions due to gastric bleeding who were treated with RT were reviewed. All patients were men with a median age of 83(range, 70-91)years. The clinical stage was ⅡB in 2 patients, Ⅲin 1, ⅣA in 1, and ⅣB in 5. Performing gastrectomy was difficult in 4 patients with distant metastasis or tumor invasion to adjacent organ, 3 with poor performance status, and 2 with advanced age. The median hemoglobin levels before RT was 6.0 (range, 3.3-7.7)g/dL, and all patients received blood transfusions before RT. Seven patients received 30 Gy RT and 2 patients received 50 Gy. Two patients received concurrent chemotherapy. A total of 2 hematological and 4 non-hematological treatment-related adverse events occurred. All patients improved conservatively. Hemorrhage occurred in 8 patients, except for 1. Of the 8 patients who responded to RT, 1 had rebleeding on day 81. The median rebleeding-free survival time from the beginning of RT was 125(range, 21-421)days. Palliative radiation therapy was useful for bleeding control in nonresectable gastric cancer.

[Short-Term Outcomes of Laparoscopic-Assisted Total Gastrectomy Using the Endoscopic Purse-String Suture Instrument ENDO-PSI].

Laparoscopic-assisted total gastrectomy(LATG)has several complications early during the introduction of the procedure, so a careful approach is necessary. In this study, we evaluated short-term outcomes after LATG at our hospital. From 2014 to 2017, 21 patients underwent LATG using ENDO-PSI. A 6-cm midline incision was made at the epigastrium, and the abdominal esophagus was transected using ENDO-PSI. The anvil head was fixed with extracorporeal ligation, and an end loop was added to the proximal side of the first suture. Reconstruction was performed with the Roux-en-Y method. The jejunojejunal anastomosis was performed extracorporeally, and esophagojejunostomy was performed using a circular stapler through the small incision. There were 15 men and 6 women, with a mean age of 74 years. The mean operation time was 296 min, and volume of blood loss was 75 mL. The median fasting period was 3(3-10)days, and the postoperative hospitalization period was 12(8-28)days. The postoperative complications were Grade Ⅱ in 4 patients and Grade Ⅲ in 1 patient. The complication due to esophagojejunostomy was anastomotic leakage in 1 patient, while no anastomotic stenosis was found. LATG using ENDO-PSI can be safely performed.

[Short-Term Comparison between Trans-Anal Ileus Tube and Self-Expandable Metallic Stent for Obstructive Colorectal Cancer].

The aim of this study was to compare the outcome of using trans-anal ileus tube and self-expandable metallic stent(SEMS) for obstructive colorectal cancer. METHODS: Between 2014 and 2018, 14 patients received trans-anal ileus tube placement (group I)and 34 received SEMS insertion as bridge to surgery(BTS)and underwent primary resection. RESULTS: The technical success rate was 100%in both groups, and the clinical success rate was 85.7%(12/14 cases)in group I and 91.2%(31/34 cases)in group S. In group S, the CROSS score significantly improved, the rates of stoma construction and postoperative complications were significantly lower, and the period until oral intake and hospital discharge was significantly short. CONCLUSION: SEMS insertion is more effective than trans-anal ileus tube placement in terms of short-term outcome.

[Efficacy and Safety of Lenvatinib for Unresectable Anaplastic Thyroid Cancer].

The 208 trial showed that lenvatinib has a significant antitumor effect on unresectable anaplastic thyroid cancer(ATC). Herein, we present a retrospective review of data from 7 patients with unresectable ATC who received lenvatinib in our hospital between May 2015 and October 2016. Two patients were men and 5 were women. The median age was 78(range, 72-85)years, and 1 patient had Stage IV A disease, 1 had Stage IV B, and 5 had Stage IV C at diagnosis, respectively. Three patients experienced a partial response and 1 patient experienced stable disease. The response rate was 43%, and the disease control rate was 57%. The median progression-free survival(PFS)was 4.1(range, 1.1-12.2)months. Grade 3 and Grade 4 gastrointestinal hemorrhage were observed in 2patients and Grade 3 anorexia was observed in 1 patient. Further clinical research seems to be needed to establish a treatment strategy involving lenvatinib for ATC.

Genomic landscape and clinical features of advanced thyroid carcinoma: a national database study in Japan.

CONTEXT: The relationship between genomic profile and prognosis of advanced thyroid carcinoma requiring drug therapy has not been reported. OBJECTIVE: To evaluate the treatment period and overall survival time for each genetic alteration in advanced thyroid carcinoma that requires drug therapy. METHODS: We conducted a retrospective observational study using a national database in Japan, which included 552 cases of thyroid carcinoma out of 53,543 patients in the database. RESULTS: The database included anaplastic thyroid carcinoma (23.6%), poorly differentiated thyroid carcinoma (10.0%), and differentiated thyroid carcinoma (66.4%). The most common genetic abnormalities were TERT promoter (66.3%), BRAF (56.7%), and TP53 (32.2%). The typical driver genes were BRAF V600E (55.0%), RAS (18.5%), RET fusion (4.7%), NTRK fusion (1.6%), and ALK fusion (0.4%). The most common regimen was lenvatinib, and the time to treatment failure was not different despite the presence of BRAF or RAS mutations. In differentiated thyroid carcinoma and poorly differentiated thyroid carcinoma, TP53 alterations independently predicted worse overall survival (hazard ratio = 2.205, 95% confidence interval: 1.135-4.283). In anaplastic thyroid carcinoma, no genetic alterations were associated with overall survival. CONCLUSION: Genetic abnormalities with treatment options were found in 62.7% of advanced thyroid carcinomas. TP53 abnormality was an independent poor prognostic factor for overall survival in differentiated thyroid carcinoma. The time to treatment failure for lenvatinib was not different based on genetic profile.

Recent Trends and Potential of Radiotherapy in the Treatment of Anaplastic Thyroid Cancer.

Anaplastic thyroid cancer (ATC) is a rare but highly aggressive malignancy characterized by advanced disease at diagnosis and a poor prognosis. Despite multimodal therapeutic approaches that include surgery, radiotherapy, and chemotherapy, an optimal treatment strategy remains elusive. Current developments in targeted therapies and immunotherapy offer promising avenues for improved outcomes, particularly for BRAF-mutant patients. However, challenges remain regarding overcoming drug resistance and developing effective treatments for BRAF-wild-type tumors. This comprehensive review examines the clinical and biological features of ATC, outlines the current standards of care, and discusses recent developments with a focus on the evolving role of radiotherapy. Moreover, it emphasizes the necessity of a multidisciplinary approach and highlights the urgent need for further research to better understand ATC pathogenesis and identify new therapeutic targets. Collaborative efforts, including large-scale clinical trials, are essential for translating these findings into improved patient outcomes.

Association of BRAF or TERT Promoter Mutations and Advanced Papillary Thyroid Carcinoma.

BACKGROUND/AIM: BRAF and TERT promoter mutations are associated with the poor prognosis of papillary thyroid carcinoma. This single-center retrospective study investigated the influence of these genes on advanced cases. PATIENTS AND METHODS: Advanced cases who underwent gene panel testing and cases who underwent complete resection were classified as groups A and C, respectively. The gene mutations were determined using gene panel testing or Sanger sequencing using tumor DNA. RESULTS: The study included 51 cases in group A and 44 cases in group C. In group A, all cases had unresectable lesions or distant metastasis; 82.4% of cases showed no accumulation of radioactive iodine in metastasis and 47.1% of cases were administered drug therapy. Meanwhile, all cases of group C did not have distant metastasis. The prevalence of TERT promoter mutations was significantly higher in group A compared to group C (70.6% vs. 18.2%, p<0.001). However, there was no significant difference in the prevalence of BRAF mutations between the two groups (86.3% vs. 90.9%). In Group C, disease-free survival was significantly shorter in patients harboring the TERT promoter mutations (p<0.001), despite no significant difference in that according to the BRAF mutation status. In addition, there was no significant difference in overall survival in group A according to the TERT promoter mutation status. CONCLUSION: Advanced papillary thyroid carcinoma was associated with the TERT promoter mutations, but not with BRAF mutation. Meanwhile, TERT promoter mutations did not affect overall survival among the advanced cases.

Selpercatinib for treating recurrent mixed medullary and follicular cell-derived thyroid carcinoma: a case report.

BACKGROUND: Mixed medullary and follicular cell-derived thyroid carcinoma (MMFCC) is characterized by the coexistence of follicular and C cell-derived tumour cell populations within the same lesion. Due to its rarity, its etiology and clinical course remain unclear, and treatment for advanced or recurrent cases has not been established. CASE PRESENTATION: We report a case of MMFCC treated with selpercatinib. The patient was a 69-year-old male presenting with tumors in the right thyroid lobe and in the upper mediastinum. Fine-needle aspiration (FNA) cytology of the right thyroid lobe tumor revealed a medullary carcinoma; germline RET mutations were not detected. After resection of the right thyroid lobe with central node dissection, rapid intraoperative diagnosis of the mediastinal mass confirmed malignancy, leading to total thyroidectomy with excision of the upper mediastinal tumor. Histologically, the tumor in the right thyroid lobe and the pretracheal lymph node revealed a mixture of medullary and follicular carcinoma components, diagnosed as MMFCC. The mediastinal lymph node exhibited only medullary carcinoma components. At 11 months postoperatively, computed tomography scans showed enlargement of the right supraclavicular and upper mediastinal lymph nodes. FNA cytology of the right supraclavicular lymph node suggested the recurrence of medullary thyroid carcinoma. The gene panel testing (The Oncomine Dx Target Test Multi-CDx system®, Thermo Fisher SCIENTIFIC) of metastatic lymph node revealed RET somatic mutation (M918T). Treatment with selpercatinib was initiated, and both the cervical and mediastinal lymph nodes showed a reduction in size. CONCLUSIONS: We report a rare case of selpercatinib use for MMFCC. Since RET mutations may occur frequently in MMFCC, selpercatinib could be effective in treating MMFCC.

Clinicopathological analysis of thyroid carcinomas with the RET and NTRK fusion genes: characterization for genetic analysis.

Thyroid carcinomas exhibit various genetic alterations, including the RET and NTRK fusion genes that are targets for molecular therapies. Thus, detecting fusion genes is crucial for devising effective treatment plans. This study characterized the pathological findings associated with these genes to identify the specimens suitable for genetic analysis. Thyroid carcinoma cases positive for the fusion genes were analyzed using the Oncomine Dx Target Test. Clinicopathological data were collected and assessed. Among the 74 patients tested, 8 had RET and 1 had NTRK3 fusion gene. Specifically, of the RET fusion gene cases, 6 exhibited "BRAF-like" atypia and 2 showed "RAS-like" atypia, while the single case with an NTRK3 fusion gene presented "RAS-like" atypia. Apart from one poorly differentiated thyroid carcinoma, most cases involved papillary thyroid carcinomas (PTCs). Primary tumors showed varied structural patterns and exhibited a high proportion of non-papillary structures. Dysmorphic clear cells were frequently observed. BRAF V600E immunoreactivity was negative in all cases. Interestingly, some cases exhibited similarities to diffuse sclerosing variant of PTC characteristics. While calcification in lymph node metastases was mild, primary tumors typically required hydrochloric acid-based decalcification for tissue preparation. This study highlights the benefits of combining morphological and immunohistochemical analyses for gene detection and posits that lymph node metastases are more suitable for genetic analysis owing to their mild calcification. Our results emphasize the importance of accurate sample processing in diagnosing and treating thyroid carcinomas.

Outcome of initial lenvatinib treatment in patients with unresectable anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is a very rare disease with a poor prognosis and with no established effective drug therapy. The present study aimed to report the outcomes of lenvatinib single-agent therapy as an initial drug treatment in ATC, and to investigate its safety and efficacy. This retrospective cohort study included 56 patients with unresectable primary ATC, of whom 36 were treated with lenvatinib and 12 with weekly paclitaxel, and 8 patients who refused any drug treatment who received palliative care. The average survival in the lenvatinib group was 5.8 months, which was significantly longer than 2.0 months in the paclitaxel group (P=0.005). The efficacy of lenvatinib in the 36 patients with ATC, whose primary tumors were unresectable, was evaluated. The response rate was 33% and the median overall survival time was 5.0 months. A safety review indicated that lenvatinib should be used under the careful observation of local findings. Two patients, who showed a reduction with lenvatinib, underwent conversion surgery, which prolonged the prognosis in terms of avoiding events, such as asphyxia, fistula and hemorrhage due to tumor growth; however, the surgical margins were positive, indicating that complete remission was impossible even if surgical resection was performed. Therefore, starting with lenvatinib treatment and identifying a therapeutic drug based on genomic analysis is an acceptable treatment strategy for ATC while halting the disease progression.

Ovarian goiter detected during post-operative follow-up of papillary thyroid cancer: a case report.

A 70-year-old female without any past medical history underwent total thyroidectomy and central neck dissection for papillary thyroid cancer (PTC) (pT3bN1aM0 pStage II). Her post-operative thyroglobulin (Tg) level remained high (around 100 ng/mL), which increased to 366 ng/mL 5 years after surgery. Computed tomography revealed metastasis to the left III and right Vb and VI lymph nodes and an incidental ovarian tumor. Transvaginal ultrasonography and magnetic resonance imaging suspected malignancy, resulting in total hysterectomy and bilateral adnexal resection. A pathological diagnosis of ovarian goiter with no malignancy was then established. For lymph node metastasis of PTC, right neck dissection and left III lymph node resection were performed. Post-operative blood examination showed a significant decrease in the Tg level (5.9 ng/mL). In conclusion, systemic imaging or I-131 remnant ablation should be performed after total thyroidectomy, as evident in the present case in which Tg levels did not decrease after total thyroidectomy.

Lenvatinib and selpercatinib successfully treated RET fusion gene-positive papillary thyroid carcinoma cardiac metastases: a case report.

Background: Cardiac metastasis from thyroid cancer is rare and has an extremely poor prognosis. Although some patients who undergo heart surgery survive, the therapeutic effectiveness of systemic therapy is limited. Case Description: A 53-year-old woman with a history of papillary thyroid carcinoma (PTC) presented with cough and right chest discomfort. She underwent total thyroidectomy, followed by three rounds of radioactive iodine therapy, to treat pulmonary metastasis. Metastases to the lung, chest wall, liver, heart, and lymph nodes were observed on computed tomography. Core needle biopsy of the tumor in the right chest wall revealed the recurrence of PTC. Cardiac metastasis was discovered by echocardiography and cardiac magnetic resonance imaging, and blood test indicated a thyroglobulin level of 851 ng/mL. Based on the presence of cardiac metastasis and strong clinical symptoms, the condition was assumed to be fatal, and lenvatinib was started right away. Three weeks after starting lenvatinib, every metastatic lesion shrank. Once the ERC1-RET fusion gene was identified, we switched to selpercatinib therapy. Ten weeks after starting selpercatinib, every tumor shrank and blood thyroglobulin dropped to 68.1 ng/mL. Initial symptoms such as cough and right chest pain improved. Lenvatinib- and selpercatinib-related adverse effects can be managed with supportive care. Conclusions: To the best of our knowledge, this is the first case of successful systemic therapy for cardiac metastasis from PTC. Conventionally, cardiac surgery is the main treatment for cardiac metastasis, but now systemic therapy is also an important alternative.

Validation of EZH2 Inhibitor Efficiency in Anaplastic Thyroid Carcinoma Cell Lines.

BACKGROUND/AIM: The prognosis of anaplastic thyroid carcinoma (ATC) is poor, and there is currently no established treatment to improve its outcome. We previously reported that enhancer of zeste homolog 2 (EZH2) was highly expressed in ATC, and may be a therapeutic target; however, the effects of EZH2 on ATC growth currently remain unknown. MATERIALS AND METHODS: We investigated the effects of an EZH2 inhibitor (DZNep) on four ATC cell lines (8305C, KTA1, TTA1 and TTA2). We performed a gene panel analysis of all ATC cell lines to identify differences in DZNep sensitivity between the cell lines. To investigate the effects of DZNep on the recovery of differentiation, we assessed changes in thyroid differentiation markers (TDMs) before and after the DZNep treatment using PCR. RESULTS: EZH2 was expressed in all ATC cell lines. The cell-reducing effects of DZNep were detected in all ATC cell lines, and were the strongest in KTA1 cells followed by TTA2 cells. The TTA1 and 8305C cell lines, which showed weak cell-reducing effects, had TP53 mutations. No changes in TDMs were observed in any ATC cell line. CONCLUSION: DZNep, an EZH2 inhibitor, exerted suppressive effects on the growth of ATC cell lines and has potential as a therapeutic strategy; however, its effects may be attenuated in ATC with TP53 mutations.

Clinical Significance of Cancer Stem Cell Markers in Primary and Metastatic Tissues in Patients With Breast Cancer.

BACKGROUND/AIM: This study aimed to examine the clinical significance of the protein expression of the cancer stem cell (CSC) markers ALDH1A1, CD133, CD44, and MSI-1 in primary and metastatic tissues of patients with breast cancer (BC). PATIENTS AND METHODS: ALDH1A1, CD133, CD44, and MSI-1 protein expression in pairs of primary and metastatic tissues of 55 patients with BC with metastases treated at Kanagawa Cancer Center between January 1970 and December 2016 were evaluated using immunohistochemical assay and their association with clinicopathological factors and survival was examined. RESULTS: There were no significant differences in CSC marker expression rates between primary and metastatic tissues for any CSC markers. Regarding the relationship between CSC marker expression in primary tissues and survival, patients with high CD133 expression had significantly lower recurrence-free survival (DFS) and overall survival. On multivariate analysis, they were also a poor independent predictor of DFS (hazard ratio=4.993, 95%CI=2.189-11.394, p=0.0001). In contrast, there was no significant association between the expression of any CSC marker in metastatic tissues and survival. CONCLUSION: CD133 expression in the primary BC tissue may be a useful risk factor for recurrence in patients with BC.

Effect of Vandetanib Treatment on Cystic Changes in the Liver following Metastasis from Medullary Thyroid Carcinoma.

A number of causes are responsible for the development of cystic lesions in the liver. However, metastasis is a rare cause, and cystic metastasis from medullary thyroid carcinoma has not yet been reported. A 46-year-old Japanese man presented to our hospital with a mass in the left side of his neck. Neck and thyroid ultrasonography revealed a thyroid tumor with calcification and enlarged cervical lymph nodes. He had a family history of medullary thyroid cancer. Computed tomography revealed a tumor in the thyroid and multiple cysts in the liver. Total thyroidectomy with modified neck and upper mediastinum dissections were performed. After surgery, vandetanib treatment was initiated owing to tumor progression; following this, the liver cysts increased in size, abdominal distension appeared, and serum liver enzyme levels were found to be elevated. Percutaneous liver cyst puncture was performed to reduce abdominal distension; however, it was ineffective. The liver enzyme levels improved after replacing vandetanib with lenvatinib treatment. The liver cysts in this case were indicated to be associated with medullary thyroid carcinoma.

Hyperthyroidism due to thyrotropin receptor antibody stimulation of metastatic thyroid carcinoma during lenvatinib treatment: a case report.

BACKGROUND: Hyperthyroidism after total thyroidectomy is extremely rare. No studies have investigated hyperthyroidism during multiple kinase inhibitor treatment for advanced thyroid carcinoma. CASE DESCRIPTION: A 57-year-old man with a history of radioactive iodine refracted thyroid follicular carcinoma presented to our hospital with back pain. Computed tomography (CT) showed a huge tumor at the left ilium and multiple metastases in the lung, liver, and bone. His serum thyroglobulin was 322,000 ng/mL and bone biopsy revealed thyroid carcinoma metastasis. After left iliac tumor decompression surgery, lenvatinib and denosumab treatment were initiated. Serum thyroglobulin decreased to 88,600 ng/mL, and no progression was observed on CT. Although thyrotropin (TSH) was suppressed at 125 µg of levothyroxine sodium, serum free T3 started to increase at 70 weeks after lenvatinib initiation. Levothyroxine sodium was gradually reduced to 25 µg. At 83 weeks after initiation, the patient was hospitalized due to nausea, diarrhea, and anorexia. Serum free T3 increased to 13.98 pg/mL, whereas CT showed progression of lung and liver metastasis. Given the patient's positivity for anti-thyrotropin receptor antibody (TRAb), levothyroxine sodium and lenvatinib were discontinued and methimazole was administered at the dose of 15 mg/day. Lenvatinib was restarted after 2 weeks withdrawal. Methimazole was gradually reduced to 5 mg/day as thyroid function normalized. However, CT showed pleural effusion and enlargement of the lung, liver, and adrenal metastases. The patient died at 100 weeks after lenvatinib initiation due to disease progression. CONCLUSIONS: The patient developed Graves' disease after lenvatinib treatment for radioactive iodine refracted thyroid follicular carcinoma. Persistent TSH stimulation caused by TRAb can be involved in tumor growth and thyroid hormone secretion from metastases.

Pulmonary cavitation in a patient with coronavirus disease 2019 during lenvatinib treatment for thyroid carcinoma: a case report.

Lenvatinib, a multi-tyrosine kinase inhibitor, is used for the treatment of thyroid carcinoma. However, it can cause pneumonia and pulmonary cavitation leading to pneumothorax. The mechanism underlying the occurrence of cavitation and pneumothorax is not well understood. Coronavirus disease 2019 (COVID-19), which is an infectious condition characterized primarily by pneumonia, is sometimes accompanied by pulmonary cavitation. Patients with COVID-19 who present with pulmonary cavitation may have a poor prognosis. In the present case, a patient with papillary thyroid carcinoma presented with multiple pulmonary metastatic tumors that were treated with lenvatinib. After 9 weeks from treatment initiation, he experienced fever and presented with pulmonary consolidation and ground-glass opacity (GGO). Pneumonia improved after the withdrawal of lenvatinib. After 21 weeks from treatment initiation, he developed fever again and the clinical tests led to the diagnosis of COVID-19. Computed tomography (CT) showed new GGO in both sides of the lung. Therefore, the patient was diagnosed with moderate COVID-19. He was treated with dexamethasone plus remdesivir, and GGO due to COVID-19 disappeared. However, the previous pulmonary shadow associated with lenvatinib became a cavitary lesion. The initial CT findings of COVID-19 and pneumonia associated with lenvatinib are similar. Thus, both conditions must be considered for a differential diagnosis in patients presenting with GGO during lenvatinib treatment.