Casler, John D.

Context and Objective:Oncocytic thyroid carcinoma, also known as Hürthle cell thyroid carcinoma, accounts for only a small percentage of all thyroid cancers. However, this malignancy often presents at an advanced stage and poses unique challenges to patients and clinicians. Surgical resection of the tumor accompanied in some cases by radioactive iodine treatment, radiation, and chemotherapy are the established modes of therapy. Knowledge of the perturbed oncogenic pathways can provide better understanding of the mechanism of disease and thus opportunities for more effective clinical management.Design and Patients:Initially, two oncocytic thyroid carcinomas and their matched normal tissues were profiled using whole genome sequencing. Subsequently, 72 oncocytic thyroid carcinomas, one cell line, and five Hürthle cell adenomas were examined by targeted sequencing for the presence of mutations in the multiple endocrine neoplasia I (MEN1) gene.Results:Here we report the identification of MEN1 loss-of-function mutations in 4% of patients diagnosed with oncocytic thyroid carcinoma. Whole genome sequence data also revealed large regions of copy number variation encompassing nearly the entire genomes of these tumors.Conclusion:Menin, a ubiquitously expressed nuclear protein, is a well-characterized tumor suppressor whose loss is the cause of MEN1 syndrome. Menin is involved in several major cellular pathways such as regulation of transcription, control of cell cycle, apoptosis, and DNA damage repair pathways. Mutations of this gene in a subset of Hürthle cell tumors point to a potential role for this protein and its associated pathways in thyroid tumorigenesis.

Abstract Context: Hürthle cell cancer (HCC) of the thyroid remains the subject of controversy with respect to natural course, treatment, and follow-up. Objective: The objective of the study was to evaluate the clinical and molecular features associated with outcome in HCC. Design: The study was a review of 173 HCC cases treated at Mayo Clinic over 11 years with a median 5.8-year follow-up. Results: None of the patients with minimally invasive histology had persistent disease, clinical recurrence, or disease-related death. Male gender and TNM stage were independently associated with increased risk of clinical recurrence or death in widely invasive patients. The 5-year cumulative probability of clinical recurrence or death was higher in patients with TNM stage III–IV (females, 74%; males, 91%) compared with patients with TNM stage I–II (females, 0%; males, 17%). Pulmonary metastases were best identified by computed tomography, whereas radioactive iodine scans were positive in only two of 27 cases. Thyroglobulin was detectable in patients with clinical disease, with the notable exception of five patients with distant metastases. The common TERT C228T promoter mutation was detected in both widely invasive and minimally invasive tumors. TERT mRNA was below the limit of detection in all samples. Conclusion: Widely invasive HCC with TNM stage III–IV is aggressive, with low probability of recurrence-free survival. Males have worse outcomes than females. Minimally invasive HCC appears to be considerably less aggressive. Radioactive iodine scan performs poorly in detecting distant disease. Although the TERT gene is mutated in HCC, the role of this mutation remains to be demonstrated.

Context: The BRAF V600E mutation (BRAF-MUT) confers an aggressive phenotype in papillary thyroid carcinoma, but unidentified additional genomic abnormalities may be required for full phenotypic expression. Objective: RNA sequencing (RNA-Seq) was performed to identify genes differentially expressed between BRAF-MUT and BRAF wild-type (BRAF-WT) tumors and to correlate changes to patient clinical status. Design: BRAF-MUT and BRAF-WT tumors were identified in patients with T1N0 and T2–3N1 tumors evaluated in a referral medical center. Gene expression levels were determined (RNA-Seq) and fusion transcripts were detected. Multiplexed capture/detection and digital counting of mRNA transcripts (nCounter, NanoString Technologies) validated RNA-Seq data for immune system-related genes. Patients: BRAF-MUT patients included nine women, three men; nine were TNM stage I and three were stage III. Three (25%) had tumor infiltrating lymphocytes. BRAF-WT included five women, three men; all were stage I, and five (62.5%) had tumor infiltrating lymphocytes. Results: RNA-Seq identified 560 of 13 085 genes differentially expressed between BRAF-MUT and BRAF-WT tumors. Approximately 10% of these genes were related to MetaCore immune function pathways; 51 were underexpressed in BRAF-MUT tumors, whereas 4 (HLAG, CXCL14, TIMP1, IL1RAP) were overexpressed. The four most differentially overexpressed immune genes in BRAF-WT tumors (IL1B; CCL19; CCL21; CXCR4) correlated with lymphocyte infiltration. nCounter confirmed the RNA-Seq expression level data. Eleven different high-confidence fusion transcripts were detected (four interchromosomal; seven intrachromosomal) in 13 of 20 tumors. All in-frame fusions were validated by RT-PCR. Conclusion: BRAF-MUT papillary thyroid cancers have reduced expression of immune/inflammatory response genes compared with BRAF-WT tumors and correlate with lymphocyte infiltration. In contrast, HLA-G and CXCL14 are overexpressed in BRAF-MUT tumors. Sixty-five percent of tumors had between one and three fusion transcripts. Functional studies will be required to determine the potential role of these newly identified genomic abnormalities in contributing to the aggressiveness of BRAF-MUT and BRAF-WT tumors.

The development of subspecialty tumor groups for uncommon malignancies represents an effective approach to building experience, increasing patient volumes and referrals, and fostering development of increased therapeutic options and clinical trials for patients afflicted with otherwise historically neglected cancers.

ObjectiveTo identify major arteries in relationship to large pharyngeal tumors during transoral laser microsurgery.Study DesignCase series with planned data collection.SettingMayo Clinic, Jacksonville, Florida.Subjects and MethodsWe developed a new technique that combines three‐dimensional CT angiography and enhanced soft‐tissue neck CT for evaluation of pharyngeal tumors before transoral laser microsurgery. Data from CT angiography were used to create three‐dimensional images of the tumor and adjacent arterial branches to better orient the surgeon to the spatial relationships of major arteries and pharyngeal tumors. Included were selected patients who had large tumors involving the pharynx and who underwent transoral laser microsurgery.ResultsEighteen patients were studied from June 2008 through January 2009. Tumor enhancement was absent or modest in four of 18 patients. Three of these four patients had superficial squamous cell carcinomas and one had adenoid cystic carcinoma. The remaining 14 patients had good tumor enhancement. The tumor involved the lingual artery in three and displaced the lingual or facial artery in two of these 14 patients. One anomalous right inferior thyroid artery was identified. Compared with routine enhanced soft‐tissue neck CT, three‐dimensional CT angiography greatly enhanced the anatomical relationships of the major arteries. In one patient, the surgeon's approach was changed after three‐dimensional CT angiography demonstrated an encased lingual artery.ConclusionThree‐dimensional CT angiography was useful in identifying the anatomical orientation of major arteries and the planning of transoral laser microsurgery to treat tumors involving the pharynx.