Prognosis and management of invasive well-differentiated thyroid cancer

Sleeve resection with end-to-end anastomosis in the reconstruction of tracheal defects exceeding six rings: a clinical feasibility study and safety assessment

Objectives

Reconstruction is always required for tracheal defects and sleeve resection with end-to-end anastomosis is the most common used. The aim of the study was to present surgical techniques and evaluate the outcomes of sleeve resection with end-to-end anastomosis in the reconstruction of tracheal defects exceeding six rings.

Methods

The study included patients with primary or secondary malignancies and tracheal stenosis from 2014 to 2019, who were treated with sleeve resection exceeding six tracheal rings, and reconstructed with end-to-end anastomosis. Airway status and patient outcomes were the principal follow-up measures.

Results

A total of 16 patients were enrolled in the study including three primary tracheal malignancies, 12 invasive thyroid carcinomas and one with tracheal stenosis. The extent of tracheal resection ranged from seven to nine rings, and the primary end-to-end anastomosis was performed in all 16 patients. Performance of tracheostomy or cricothyroidotomy was done in 6 patients with decannulation at a median of 42 days (range, 28-56). No anastomotic dehiscence, infection or bleeding occurred postoperatively, and all 16 patients maintained an unobstructed airway through the end of follow-up.

Conclusions

Sleeve resection reconstructed with end-to-end anastomosis can serve as an appropriate therapeutic strategy for the tracheal defects even exceeding six rings. Adequate laryngeal release is the key to surgical success.

How I Do It: Sternocleidomastoid Flap Augmentation of Tracheal Repair After Resection for Invasive Thyroid Cancer

Surgical treatment for thyroid carcinoma invading the trachea often involves circumferential tracheal resection and primary tracheal repair. This procedure involves a significant risk of anastomotic breakdown. We present a novel approach to cricotracheal repair using an SCM flap bolster designed to reduce the risk of anastomotic complications. Laryngoscope, 133:3228-3231, 2023.

Surgical Methods and Social Factors Are Associated With Long-Term Survival in Follicular Thyroid Carcinoma: Construction and Validation of a Prognostic Model Based on Machine Learning Algorithms

Background

This study aimed to establish and verify an effective machine learning (ML) model to predict the prognosis of follicular thyroid cancer (FTC), and compare it with the eighth edition of the American Joint Committee on Cancer (AJCC) model.

Methods

Kaplan-Meier method and Cox regression model were used to analyze the risk factors of cancer-specific survival (CSS). Propensity-score matching (PSM) was used to adjust the confounding factors of different surgeries. Nine different ML algorithms,including eXtreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), Random Forests (RF), Logistic Regression (LR), Adaptive Boosting (AdaBoost), Gaussian Naive Bayes (GaussianNB), K-Nearest Neighbor (KNN), Support Vector Machine (SVM) and Multi-Layer Perceptron (MLP),were used to build prognostic models of FTC.10-fold cross-validation and SHapley Additive exPlanations were used to train and visualize the optimal ML model.The AJCC model was built by multivariate Cox regression and visualized through nomogram. The performance of the XGBoost model and AJCC model was mainly assessed using the area under the receiver operating characteristic (AUROC).

Results

Multivariate Cox regression showed that age, surgical methods, marital status, T classification, N classification and M classification were independent risk factors of CSS. Among different surgeries, the prognosis of one-sided thyroid lobectomy plus isthmectomy (LO plus IO) was the best, followed by total thyroidectomy (hazard ratios: One-sided thyroid LO plus IO, 0.086[95% confidence interval (CI),0.025-0.290], P<0.001; total thyroidectomy (TT), 0.490[95%CI,0.295-0.814], P=0.006). PSM analysis proved that one-sided thyroid LO plus IO, TT, and partial thyroidectomy had no significant differences in long-term prognosis. Our study also revealed that married patients had better prognosis than single, widowed and separated patients (hazard ratios: single, 1.686[95%CI,1.146-2.479], P=0.008; widowed, 1.671[95%CI,1.163-2.402], P=0.006; separated, 4.306[95%CI,2.039-9.093], P<0.001). Among different ML algorithms, the XGBoost model had the best performance, followed by Gaussian NB, RF, LR, MLP, LightGBM, AdaBoost, KNN and SVM. In predicting FTC prognosis, the predictive performance of the XGBoost model was relatively better than the AJCC model (AUROC: 0.886 vs. 0.814).

Conclusion

For high-risk groups, effective surgical methods and well marital status can improve the prognosis of FTC. Compared with the traditional AJCC model, the XGBoost model has relatively better prediction accuracy and clinical usage.

A novel classification of tracheal defects and the reconstruction strategies: A retrospective study based on 106 cases

Objective

The study aims to present a novel classification of tracheal defects and the corresponding reconstruction strategies.

Methods

The retrospective study was designed to analyze patients with diagnosed primary or secondary tracheal tumors from 1991 to 2020. Surgical techniques, complications and prognosis were reviewed. Airway status and patient outcomes were the principal follow-up measures. Tracheal defects were classified into two plane sizes (vertical (V) and horizontal (H) planes). Vertical defects were further categorized into three groups based on their tracheal ring numbers (V₁, ≤ 5 rings; V₂, 6-10 rings; and V₃, > 10 rings). Tracheal defects with horizontal plane size H₁ and H₂ represent defects less and more than one-half the circumference of trachea. Thus, suitable reconstruction strategies were planned primarily based on "V" and "H" classifications. The reconstruction strategies performed were sleeve resection followed by an end-to-end anastomosis, window resection with sternocleidomastoid myoperiosteal flap reconstruction, defects conversion with rotation anastomosis, and modified tracheostomy with secondary flap reconstruction.

Results

A total of 106 patients diagnosed with tracheal defects were enrolled in the study, of whom 59 patients underwent sleeve resection followed by end-to-end anastomosis; 40 patients received window resection alongside sternocleidomastoid (SCM) myoperiosteal flap reconstruction; five patients received converting defects with rotation anastomosis and two patients underwent modified tracheostomy with secondary stage flap reconstruction. Lumen stenosis occurred in three V₂H₁ defect cases and were treated by a second reconstruction surgery. Iatrogenic unilateral recurrent laryngeal nerve paralysis occurred in two patients with the V₃H₂ defect type, who were treated by temporary tracheotomy and partial vocal cord resection and extubated successfully during follow-up. All 106 patients achieved airway patency with adequate laryngeal function at the end of follow-up. No anastomotic dehiscence or bleeding occurred in any patient postoperatively.

Conclusion

Though a significant number of multicenter studies concerning the reconstruction and classification of tracheal defects are needed, the study herein provides a novel classification of tracheal defects, which is primarily developed on the defect size. Therefore, the study might serve as a potential source for identifying suitable reconstruction strategies for practitioners.

Tracheal window resection and reconstruction via sternocleidomastoid flap for invasive thyroid carcinoma

OBJECTIVES

The aim of this study was to present surgical techniques and evaluate outcomes of a sternocleidomastoid muscle (SCM) myoperiosteal flap used for the reconstruction of tracheal or laryngotracheal defects after the radical resection of invasive thyroid carcinoma.

METHODS

A retrospective study was performed for patients at Peking Union Medical College Hospital from January 2008 to December 2018 of papillary thyroid carcinoma with tracheal or laryngotracheal invasion. Patients were enrolled only when they received window resection and reconstruction via an SCM myoperiosteal flap. The primary outcome was a stable airway, and the secondary outcome was survival.

RESULTS

A total of 15 invasive thyroid carcinoma patients were enrolled in this study. Laryngotracheal and tracheal reconstruction were performed in 11 and 4 patients respectively, with a median vertical defect of 3.5 cm (3.0, 4.5). A stable airway was achieved in 14 patients postoperatively. One patient experienced tracheal stenosis and received a second operation of tracheal sleeve resection and end-to-end anastomosis 105 days after the first operation. Tracheostomy was conducted in 5 out of 15 patients in whom the vertical defects were larger than 4 cm, and the tubes were extubated after a median time of 56 days (32, 84). The median observation time was 55 months (48, 86), and all 15 patients achieved a stable airway and showed no evidence of local recurrence at the end of follow-up.

CONCLUSIONS

For thyroid carcinoma with tracheal or laryngotracheal invasions, window resection with the SCM myoperiosteal flap reconstruction presented positive results in terms of a stable airway as well as oncological outcomes. The SCM myoperiosteal flap can be an appropriate reconstruction strategy, especially when the defects reach the thyroid cartilage.

Well-Differentiated Thyroid Cancer Invading the Trachea in a Pediatric Patient

Objectives

Pediatric thyroid cancer is rare. Most cases are well-differentiated thyroid cancers (WDTCs). However, gross laryngotracheal invasion of WDTCs is unusual. This report details the first case in English medical literature of a pediatric WDTC invading the trachea.

Methods

Thyroid stimulating hormone, free triiodothyronine, free thyroxine, thyroglobulin, parathyroid hormone, calcitonin, thyroglobulin antibody, chest magnetic resonance imaging, neck ultrasound, neck computed tomography, and fine needle aspiration were performed.

Results

A 9-year-old boy with moderate persistent asthma presented with increasing upper respiratory symptoms. Spirometry suggested a fixed upper airway obstruction. Chest x-ray revealed a left tracheal shift, and chest magnetic resonance imaging identified a right thyroid mass. Thyroglobulin level was 809 ng/mL (normal, ≤33 ng/mL). Results of thyroid stimulating hormone, free triiodothyronine, free thyroxine, parathyroid hormone, calcitonin, and thyroglobulin antibody were normal. Neck ultrasound revealed 2 right thyroid lobe nodules. Neck computed tomography revealed tracheal compression. Fine needle aspiration of the largest nodule yielded atypia of undetermined significance. Bronchoscopy findings at his local hospital were concerning for tracheal invasion. He underwent total thyroidectomy, cricotracheal resection, reconstruction, and radioactive iodine therapy (220 mCi). Pathology demonstrated a well-differentiated papillary thyroid carcinoma without solid or diffuse sclerosing subtype components. Tumor cytogenetic and single nucleotide polymorphism microarray studies showed normal findings. One year postoperatively, neck ultrasound demonstrated no recurrence, and thyroglobulin levels were undetectable while on levothyroxine therapy.

Conclusion

Pediatric WDTC invading the trachea has not been reported.

Surgical Management of Tracheal Invasion by Well-Differentiated Thyroid Cancer

Simple Summary

Tracheal invasion is a poor prognostic factor in well-differentiated thyroid cancer. Appropriate resection can improve the prognosis and maintain the patient’s quality of life. Shaving resection for superficial tracheal invasion is minimally invasive because it does not involve the tracheal lumen, despite the problematic risk of local recurrence. Window resection for tracheal mucosal and luminal invasion provides good tumor control and does not cause postoperative airway obstruction; however, the need for surgical closure of the tracheocutaneous fistula is a disadvantage of this method. Circumferential (sleeve) resection and end-to-end anastomosis are highly curative, but the risk of fatal complications, such as anastomosis dehiscence, is a concern.

Abstract

Well-differentiated thyroid carcinoma (WDTC) is a slow-growing cancer with a good prognosis, but may show extraglandular progression involving the invasion of tumor-adjacent tissues, such as the trachea, esophagus, and recurrent laryngeal nerve. Tracheal invasion by WDTC is infrequent. Since this condition is rare, relevant high-level evidence about it is lacking. Tracheal invasion by a WDTC has a negative impact on survival, with intraluminal tumor development constituting a worse prognostic factor than superficial tracheal invasion. In WDTC, curative resection is often feasible with a small safety margin, and complete resection can ensure a good prognosis. Despite its resectability, accurate knowledge of the tracheal and peritracheal anatomy and proper selection of surgical techniques are essential for complete resection. However, there is no standard guideline on surgical indications and the recommended procedure in trachea-invading WDTC. This review discusses the indications for radical resection and the three currently available major resection methods: shaving, window resection, and sleeve resection with end-to-end anastomosis. The review shows that the decision for radical resection should be based on the patient’s general condition, tumor status, expected survival duration, and the treating facility’s strengths and weaknesses.

From the clavicle to the windpipe: Tracheal window resections reconstructed with calcifying periosteum in thyroid cancer

OBJECTIVES

We aimed to evaluate the outcomes of tracheal window resection and reconstruction using a vascularized periosteal flap (intended for calcification) harvested from the medial clavicle. This is one of several surgical techniques for tracheal resection and reconstruction used for patients with thyroid carcinoma invading the trachea. Importantly, in partial tracheal resection postoperative dynamic airway collapse must be prevented. Reconstruction of the tracheal defect with a vascularized periosteal flap is one method of achieving a stable airway.

METHODS

Twelve patients with locally advanced thyroid carcinoma who underwent tracheal resection and reconstruction at Oslo University Hospital from 2004 to 2017 were studied retrospectively. The primary outcome was a stable airway not requiring airway stenting. The secondary outcomes were the time to decannulation, morbidity, and survival.

RESULTS

Eleven of 12 patients did not require airway stenting postoperatively after a median of 111 days. Seven patients developed postoperative complications. The median observation time was 74.8 months (range 10.5-153.5) for all patients. The median disease-free survival was 40 months (range 0-147). By February 1, 2020, seven patients were alive, of whom five showed no evidence of disease.

CONCLUSIONS

Tracheal reconstruction with a vascularized periosteal flap yielded good results in terms of establishing a stable airway. This procedure is a viable reconstructive option that allows for decannulation by preventing airway collapse, thereby potentially mitigating the need for end-to-end (ETE) anastomosis or sleeve resections. For selected patients, this procedure may prevent local fatal complications from thyroid cancer invading the trachea.

LEVEL OF EVIDENCE

Level 4.

Microarray analysis of formalin-fixed, paraffin-embedded follicular thyroid carcinoma samples from patients who developed postoperative distant metastasis

Objective

Although follicular thyroid carcinoma (FTC) generally has a good prognosis, it occasionally metastasises, leading to poor prognosis. Unfortunately, minimally invasive FTC (mi-FTC) and encapsulated angioinvasive FTC (ea-FTC) cannot be distinguished cytopathologically from thyroid follicular adenoma (FTA), a benign tumour with a good prognosis. Therefore, a molecular diagnosis to distinguish mi- or ea-FTC from FTA is needed for clinical treatment. Several transcriptomics/proteomics studies have searched for FTC biomarkers. However, the results of these studies were not consistent, which could be partly explained by inaccurate diagnosis of the specimens analysed.

Data description

We conducted a microarray-based genome-wide transcriptome analysis using formalin-fixed paraffin-embedded mi- or ea-FTC specimens from patients who developed distant metastasis up to 10 years postoperatively, which ensured the accuracy of diagnosis.

Stair-step tracheal repair: Surgical technique

Typical surgical treatment for invasive thyroid carcinoma at the level of the cricoid substantially reduces surrounding cartilaginous support and risks damage to the recurrent laryngeal nerve (RLN). We present a novel tracheal reconstructive technique that minimizes this injury risk. A 72-year-old man with recurrent invasive thyroid carcinoma underwent cricotracheal resection and reconstruction using a stair-step approach. Diseased cartilage was removed by a left hemitracheal and hemicricoid resection. A portion of normal trachea was also resected on the contralateral right side, removing the third and fourth hemitracheal rings, to close the defect with a sliding tracheoplasty and avoid dissection near the right cricothyroid joint on the side of the functioning RLN. The trachea was elevated superiorly and reanastomosed to the cut margin of the cricoid. This novel stair-step approach to tracheal reconstruction offers reduced risk of injury to the contralateral RLN while still establishing a patent airway.

Tracheal/Laryngeal Infiltration in Thyroid Cancer: a Single-Centre Experience

Around 1/3 of patients of locally advanced carcinoma thyroid present with tracheal infiltration either alone or along with infiltration of other adjacent structures. Even though trachea is infiltrated, adequate resection is the main modality of treatment in these patients. We retrospectively analysed carcinoma thyroid patients who were operated at our institute, between January 2011 and December 2018, and underwent thyroidectomy with tracheal or laryngeal resection. Seventeen patients underwent tracheal/laryngeal resection with thyroidectomy. The mean age of patients was 57 years. Six and eleven were male and female, respectively, 0.14 (82%) patients had dyspnoea on presentation, 6 had hoarseness of voice, 6 had haemoptysis, and in 2 patients, neck swelling was the only complain. Two patients in our study presented with acute stridor, underwent emergency intubation and subsequently surgery. Two other patients had bulky pedunculated tumour in preoperative bronchoscopy and required tracheostomy for intubation before proceeding with surgery. In 11 patients, sleeve resection followed by end-to-end anastomosis was done, window resection was done in 3 patients, partial laryngectomy in 1, and total laryngectomy in 2 patients. In 10 patients (59%), the site of infiltration was in the lateral tracheal wall, with relatively small posterior primary (mean size 3.7 cm) in the thyroid lobe. Two patients developed postoperative complication, one patient with sleeve resection had secondary haemorrhage, and one patient who underwent window resection with myochondrial thyroid lamina flap reconstruction developed salivary fistula. These patients underwent re exploration with tracheostomy and were subsequently decannulated. Preoperative diagnosis of tracheal infiltration helps in better planning of surgery and counseling the patients of any possible complication. Clinical workup and pre-emptive diagnosis is therefore of paramount importance.

The Clinical Importance of Tumor Thrombus in Internal Jugular Vein Related to Papillary Thyroid Cancer

Objective: We aimed to present a case with a previous thyroid surgery, who developed an internal jugular vein thrombus due to papillary thyroid cancer (PTC) in the remnant tissue. Case: A 54-year-old female patient, with a previous subtotal thyroidectomy, presented with a mass on the left side of her neck. Thyroid ultrasound disclosed a heterogeneous nodule of 67x48x32 mm in the left thyroid lobe. An isoechoic tumor thrombus was observed extending intraluminally from the middle thyroid vein to the internal jugular vein. No lymph node or solid organ invasion were detected in the neck. Fine needle aspiration biopsy revealed cytological findings consistent with PTC. Total thyroidectomy, left sided central neck dissection and partial left jugular vein resection was performed. The pathologic examination revealed mid-differentiated unifocal encapsulated follicular variant of PTC. The whole-body scan performed after the postoperative treatment of 150 mCi of radioactive iodine, revealed multiple lung metastases. Conclusion: The presence of a tumor thrombus in the thyroid vein or internal jugular vein is strongly suspicious for malignancy even in the absence of malignant findings on cytology. It is an important finding that is highly suspicious for distant metastasis in the cytologically diagnosed patients.

A Successful Tracheal Resection and Anastomosis in Papillary Thyroid Carcinoma with Tracheal Invasion

BACKGROUND:

Well-differentiated thyroid carcinoma (DTC) can be locally aggressive, invading aerodigestive tract. The rationale for aggressive surgical resection in this clinical setting is supported by a long-term local control with a positive impact on survival.

CASE REPORT:

A 60-year-old male patient was consulted by a digestive surgeon of unaware thyroid enlargement. Physical and imaging examination showed a suspect of thyroid malignancy. During surgery, we found that a tumour had invaded the anterior side of the trachea. Resection of three tracheal rings was performed, with end-to-end anastomosis. Surgical outcome regarding nervous preservation and parathyroid glands was good as well as cosmetic aspect. During one-year follow-up, no indication of tumour recurrence was found. The management of locally invasive DTC has been controversial yielding the palliative surgery modalities. Advances in surgical technique have given a new perspective of resection in a difficult case. This case report was managed by sleeve resection with end-to-end anastomosis which showed a satisfactory outcome functionally and cosmetically.

CONCLUSION:

Sleeve resection with primary reconstruction of the trachea is a simple one-stage procedure which can adequately address the problem of tracheal invasion by thyroid cancer.

TIPE2 acts as a biomarker for tumor aggressiveness and suppresses cell invasiveness in papillary thyroid cancer (PTC)

Background

Tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a newly described negative immune regulator and is closely associated with various tumors. However, the expression and roles of TIPE2 in PTC is unknown.

Results

In the present study, TIPE2 upregulation in PTC tissues was found to be negatively associated with tumor size, capsule infiltration, peripheral infiltration and tumor T stage, which could be used to predict tumor invasiveness. TIPE2 overexpression significantly suppressed the viability, proliferation, migration and invasion of PTC cells. Moreover, TIPE2 suppressed tumor invasiveness by inhibiting Rac1, leading to decreased expression of uPA and MMP9.

Conclusions

These results indicate that TIPE2 is a potential biomarker for predicting tumor aggressiveness and suppresses tumor invasiveness in a Rac1-dependent manner.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0247-x) contains supplementary material, which is available to authorized users.

Tracheal and Crico-Tracheal Resection and Anastomosis for Malignancies Involving the Thyroid Gland and the Airway

Objectives:

To evaluate outcomes in different malignancies involving the thyroid and infiltrating the airway submitted to tracheal (TRA) or crico-tracheal resection and anastomosis (CTRA).

Methods:

Retrospective charts review of 27 patients affected by thyroid malignancies involving the airway treated by TRA/CTRA in a single academic institution. Kaplan-Meier curves were used to evaluate the overall (OS) and disease-specific (DSS) survivals and local (LC) and loco-regional control (LRC). Impact on survival of age, comorbidities, previous radiotherapy, types of TRA/CTRA, Shin’s stage (II, III, IV), grading (well vs poorly differentiated), and length of airway resected was calculated by the log-rank test.

Results:

Overall survival and DSS at 3 and 5 years were 82.3% and 71.6%, respectively. Local control and LRC in the entire group were 82.3% at 3 and 5 years. Crico-tracheal resection and anastomosis involving the cricoid arch and plate (type C) and tumor differentiation significantly affected OS and DSS (both P < .001). Type C CTRA and tumor differentiation significantly impacted on LC ( P = .002 and P = .009, respectively).

Conclusions:

Grading and extension of CTRA to the cricoid plate are the most important factors for oncologic outcomes in thyroid malignancies infiltrating the airway. Except for poorly differentiated tumors, TRA/CTRA allows adequate LC even in advanced stage lesions involving the crico-tracheal junction.

Resection margins and prognosis in locally invasive thyroid cancer

BACKGROUND

Invasive thyroid cancer is rare, and the extent of surgery controversial. The purpose of this study was to present and evaluate therapeutic prognostic factors.

METHODS

We conducted a retrospective single-center study of differentiated thyroid carcinoma invading the larynx, trachea, and/or esophagus treated surgically with macroscopic complete resection.

RESULTS

Forty-six patients (average age, 57 years; average follow-up, 4 years) were included. Free margins (R0) were obtained for 22 of 46 (49%) and microscopic residual tumor was present after surgery (R1) for 24 (51%). Ten-year actuarial local control was 100% for R0 and 75% for R1 (p = .08). Five-year local control was lower for recurrent tumors versus inaugurally invasive disease (63% vs 87%; log-rank p = .011). Five-year and 10-year actuarial disease-specific survival (DSS) was correlated with preoperative distant metastases (100% and 87%, respectively, for M0 vs 68% and 34% for M1; p = .01).

CONCLUSION

A trend toward lower local control was observed for R1 versus R0. The morbidity of surgery should be weighed against the prognosis if metastases are present.

Management of well-differentiated thyroid cancer

This review provides an overview of current guideline recommendations for the clinical evaluation and surgical management of well-differentiated thyroid cancer, and further examines the evidence for controversial topics such as the minimum degree of primary resection, the role of elective central neck dissection, and the extent of lateral neck dissection. Well-differentiated thyroid cancer comprises the majority of thyroid cancers, about 90%, and includes both papillary and follicular carcinomas. Despite convergence of the medical community in establishing treatment guidelines under the American Thyroid Association, there still remain many areas of disagreement.

Role of Caspase 8, Caspase 9 and Bcl-2 polymorphisms in papillary thyroid carcinoma risk in Han Chinese population

Dysregulation of apoptosis plays a key role in carcinogenesis. This study was designed to investigate the association of apoptosis-related gene Caspase 8, Caspase 9 and Bcl-2 polymorphisms with papillary thyroid carcinoma (PTC) susceptibility. We undertook a case-control study of 118 patients and 213 controls to investigate the association between Caspase 8 (-652 6 N ins/del), Caspase 9 (-1263 A>G) and Bcl-2 (-938 C>A) polymorphisms and PTC susceptibility by polymerase chain reaction restriction-fragment length polymorphism and DNA sequencing methods. We further analyzed the distribution of genotype frequency, as well as the association of genotype with clinicopathological characteristics. Overall, no statistically significant association was observed in Caspase 8 (-652 6 N ins/del). Nevertheless, Caspase 9 -1263 GG genotype was at increased risk of PTC (P=0.045; odds ratio (OR)=1.12). Furthermore, GG genotype thyroid cancers were significantly more common in older patients than AA or AG genotypes PTC and in cases of advanced pathological stages. However, Bcl-2 -938 AA genotype demonstrated a protective effect in PTCs (P=0.004; OR=0.35). Polymorphism in Caspase 9 (-1263 A>G) was observed to be associated with susceptibility of PTC. However, Bcl-2 (-938 C>A) polymorphism indicated to play a protective role in susceptibility to PTC. Nevertheless, further investigation with a larger sample size is needed to support our results.

The role of epigenetic alterations in papillary thyroid carcinogenesis

Papillary thyroid carcinoma (PTC) accounts for over 80% of all thyroid malignancies. The molecular pathogenesis remains incompletely clarified although activation of the RET fusion oncogenes, and RAS and BRAF oncogenes, has been well characterized. Novel technologies using genome-wide approaches to study tumor genomes and epigenomes have provided great insights into tumor development. Growing evidence shows that acquired epigenetic abnormalities participate with genetic alterations to cause altered patterns of gene expression/function. It has been established beyond doubt that promoter cytosine methylation in CpG islands, and the subsequent gene silencing, is intimately involved in cancer development. These epigenetic events very likely contribute to significant variation in gene expression profiling, phenotypic features, and biologic characteristics seen in PTC. Hypermethylation of promoter regions has also been analyzed in PTC, and most studies have focused on individual genes or a small cohort of genes implicated in tumorigenesis.