Management of well-differentiated thyroid cancer

Multifocal metastases to choroid plexus from papillary thyroid carcinoma: illustrative case

BACKGROUND

Choroid plexus metastases are extremely rare from all types of malignancy, with only 42 cases reported in the literature thus far. Most of these originate from renal cell carcinoma and present as a solitary choroid plexus lesion; only two cases of multifocal choroid plexus metastases have been reported to date.

OBSERVATIONS

The authors report the third case of multifocal metastases to the choroid plexus, that of a 75-year-old man who developed three measurable choroid plexus lesions approximately 3.5 years after undergoing total thyroidectomy and chemotherapy for papillary thyroid carcinoma. He underwent intraventricular biopsy of the largest lesion and subsequently died of hydrocephalus after opting for comfort care only.

LESSONS

This is the third case of multifocal choroid plexus metastasis in the literature and the second case of multifocal metastasis from thyroid carcinoma. As such, the natural disease course is not well characterized. This case is compared with the previous eight reports of choroid plexus metastases from thyroid carcinoma, seven of which involved solitary lesions. The eight prior cases are evaluated with attention to treatment modalities used and factors potentially influencing prognosis, specifically those that might contribute to hydrocephalus, a reported complication for this pathology.

Diagnostic Accuracy of Ultrasound for the Evaluation of Lateral Compartment Lymph Nodes in Papillary Thyroid Carcinoma

AIMS

To evaluate the diagnostic accuracy of ultrasound (US) assessing the lateral compartment lymph node metastasis in patients with primary papillary thyroid carcinoma (PTC), and to demonstrate the incidence and patterns of the lateral lymph node metastasis.

METHODS

We retrospectively reviewed 198 patients with primary PTC who underwent thyroidectomy in addition to modified lateral neck dissections (MLND) involving level II to level V due to clinically positive lateral neck disease. A skilled and experienced single operator performed all US examinations. Surgical pathology results were accepted as the reference method and sensitivity, specificity, and diagnostic accuracy of US in detecting metastatic lymph nodes established using level-by-level analysis.

RESULTS

In the study cohort, 10.1% of the patients had lateral compartment lymph node metastases without any central compartment involvement. For the lateral compartment, 48.5% had level II, 74.7% had level III, 64.6% had level IV, and 29.3% of the patients had level V metastasis. None of the patients had isolated level V metastasis. The sensitivity, specificity, and diagnostic accuracy of US in identifying lateral lymph compartment metastasis ranged from 87% to 91.4%, 92% to 98.6% 92.4% to 96%, respectively. However, the sensitivity (74.7%) and diagnostic accuracy (76.2%) of US significantly decreased for the central compartment while specificity (90%) remained similar.

CONCLUSION

US performed by a skilled operator has an excellent diagnostic accuracy for the evaluation of lateral cervical lymph nodes in primary PTC; thus, might enable precise tailoring of the management strategies. Moreover, the high incidence of level V involvement favors MLND over selective approaches.

Combination of peroxisome proliferator-activated receptor gamma and retinoid X receptor agonists induces sodium/iodide symporter expression and inhibits cell growth of human thyroid cancer cells

BACKGROUND

Thyroid tumors are the most frequent neoplasm of the endocrine system. The major treatment is surgical intervention followed by radioiodine therapy. The sodium/iodide symporter (NIS) has positive expression in thyroid carcinomas with good prognoses and plays a critical role in radioiodine therapy response. Low expression of NIS always leads to tumor recurrence or treatment failure. Redifferentiation therapy is more tumor specific than chemotherapy. Peroxisome proliferator-activated receptor gamma (PPARγ) agonists and retinoids are two types of redifferentiating agents. In this study, we examined whether the PPARγ agonist rosiglitazone and retinoid X receptor (RXR) agonist bexarotene could increase NIS expression and exhibit anticancer activity in human thyroid cancer cells.

METHODS

Using a TCGA data set, we analyzed the expression of NIS (SLC5A5), PPARγ, and RXR in clinical thyroid tumors and assessed their correlations with the relapse-free survival (RFS) of thyroid tumor patients. Moreover, two human thyroid cancer cell lines, differentiated thyroid papillary BCPAP cells and follicular follicular thyroid cancer-131 cells, were treated with different concentrations of the PPARγ agonist rosiglitazone alone or in combination with the RXR agonist bexarotene. Cell growth was analyzed by the MTT assay. NIS protein expression was determined by Western blotting.

RESULTS

From analysis of the TCGA data set, we found that thyroid tumors have lower expression of both NIS (SLC5A5) and PPARγ than nontumor controls. Higher expression levels of NIS, PPARγ, and RXR are associated with higher RFS in patients with thyroid tumors. Moreover, rosiglitazone treatment reduced cell growth and increased NIS protein expression in thyroid cancer cells under normoxic or hypoxic conditions. In addition, bexarotene potentiated the effects of rosiglitazone on cell growth and NIS protein expression.

CONCLUSION

Our results suggest that the combination of PPARγ and RXR agonists has potential as a chemotherapeutic strategy for thyroid cancer.

Neck Dissection in the Surgical Treatment of Thyroid Cancer

The incidence of thyroid cancer is increasing, largely attributable to overdetection related to prevalent diagnostic and radiologic imaging modalities. Papillary thyroid cancer remains the most common thyroid malignancy. It has a high tendency for regional metastasis to the cervical lymph nodes. The optimal management of the neck in patients with thyroid carcinoma has long been an important topic of debate. This article addresses central and lateral neck dissection, providing a simplified guide to the most up-to-date and evidence-based practices.

Standards and Definitions in Neck Dissections of Differentiated Thyroid Cancer

Papillary and follicular thyroid carcinomas arising from the follicular epithelial cells and forming differentiated thyroid cancer (DTC) consist of >95% of thyroid cancers. Lymph node metastasis to the neck is common in DTC, especially in papillary thyroid cancer. The removal of only the metastatic lymph nodes (berry picking) does not help to achieve a potential positive contribution to the survival and recurrence of lymph node dissection in the DTC. Thus, systematic dissection of the cervical lymph nodes is needed. Today, according to the widely accepted and commonly used definitions and lymph node staging, the deep lymph nodes of the lateral side of the neck are divided into five regions. Based on the fact that some groups have biologically independent regions, Groups I, II, and V are divided into the A and B subgroups. The central region lymph nodes contain VI and VII region lymph nodes, which consist of the prelaryngeal, pretracheal, and right and left paratracheal lymph node groups. Radical neck dissection (RND) is accepted as the standard basic procedure in defining neck dissections. In this method, in addition to all the regions of the Groups I-V lymph nodes at one side, the ipsilateral spinal accessory nerve, internal jugular vein, and sternocleidomastoid muscle are removed. Sparing of one or more of the routinely removed non-lymphatic structures in the RND is called modified RND (MRND), whereas the preservation of one or more of the routinely removed lymph node groups in the RND is termed as selective neck dissection (SND). In difference, the procedure with an addition of a lymph node and/or non-lymphatic structures to routinely removed neck structures in RND is called extended RND. Generally, involving one or more regions of SND are applied for DTC. The removal of the paratracheal, prelaryngeal, and pretracheal lymph node groups at one side is termed as ipsilateral central dissection, whereas the removal of the bilateral paratracheal lymph node groups, in other words, the excision of four lymph node groups in the central region (Groups VI and VII), is defined as bilateral central dissection. In conclusion, bilateral central neck dissection (CND) is the SND in which the regions of VI and VII are removed. In the DTC, CND is prophylactically and therapeutically applied, whereas lateral neck dissection is performed only therapeutically in the presence of clinical metastasis (N1b) in the lateral neck region. Debates on the extent of SNDs to be made in the central and lateral neck regions are still ongoing. Central dissection should be made at least unilaterally. In the lateral side of the neck, SNDs can be applied in different combinations in which at least one region from Groups I to V is removed. The main variables that determine the extent of SND in the central and lateral regions in DTC are the complication rates, the effect of the procedure, and its effect on prognosis and recurrence.

Recurrence of differentiated thyroid carcinoma during full TSH suppression: is the tumor now thyroid hormone dependent?

Well-standardized primary treatment and long-term management of differentiated thyroid carcinoma (DTC) include lowering or suppression of host thyrotropin (TSH) with exogenous L-thyroxine (T₄). This treatment recognizes the trophic action of TSH on DTC cells. Suppression of endogenous TSH with T₄ is continued in recurrent disease. However, T₄ can induce proliferation of follicular and papillary thyroid carcinoma cell lines and of other human carcinoma cells. The proliferative mechanism is initiated at a cell surface receptor for T₄ on integrin αvβ3, a receptor by which the hormone also inhibits p53-dependent apoptosis in tumor cells. In recurrent DTC with satisfactory suppression of endogenous TSH, we discuss here the possibility that the tumor is no longer TSH dependent and that T₄ has become a critical growth factor for the cancer.

Serum thyroglobulin improves the sensitivity of the McGill Thyroid Nodule Score for well-differentiated thyroid cancer

BACKGROUND

The McGill Thyroid Nodule Score (MTNS) is a scoring system devised to help physicians to assess the preoperative risk that a thyroid nodule is malignant. It uses 22 different known risk factors for thyroid cancer (radiation exposure, microcalcifications on ultrasound, positive HBME-1 stain on biopsy, etc.) and attributes a percentage risk that the nodule is malignant. Recently, preoperative thyroglobulin (Tg) levels have been shown to correlate with the risk of malignancy. The aim of this study was to incorporate Tg levels into the already established MTNS.

METHODS

This is a retrospective analysis of 184 thyroidectomy patients at the McGill University Thyroid Cancer Center. Patients with preoperative Tg levels were included in the study, and patients with incidental papillary microcarcinoma without extrathyroidal extent on final pathology were excluded. MTNS scores were calculated for all patients. Preoperative Tg levels of 75 ng/mL added one point to the MTNS, and levels of 187.5 ng/mL added two points. The new system is named MTNS+.

RESULTS

Malignancy rates were calculated for each MTNS+ score. Patients with a score of 0-1 were <5% at risk of malignancy. The malignancy rate for scores of 2-3 was 14.29%, followed by 28.95% for scores of 4-6, 32.65% for scores of 7-8, 64.86% for scores of 9-11, 71.43% for scores of 12-14, 78.57% for scores of 15-18, and 92.31% for scores of 19-22. All patients (five of five) with an MTNS+ score of 23 or more had a malignant final pathology result. Patients with scores greater than eight had a relative risk of 2.5 [CI 1.79-3.49] of malignancy compared to patients with lower scores. MTNS+ showed good specificity at higher scores, with 89%, 96%, and 100% at scores above 11, 14, and 20 respectively. Compared to MTNS, adding Tg levels did not improve positive predictive values (PPV) or specificity, but improved sensitivity by 7.89% for scores greater than eight, and by up to 10.48% for scores greater than seven.

CONCLUSION

This study shows that adding Tg to the MTNS increases the sensitivity of this scoring system. Moreover, it suggests that a combined scoring system such as the MTNS+ can accurately stratify the risk of well-differentiated malignancy in patients with thyroid nodules.

Complications of completion versus total thyroidectomy

INTRODUCTION

The objective of this study was to analyze the complication rates after completion thyroidectomy and compare them with primary total benign and malign thyroidectomy causes in total of 647 patients.

PATIENTS AND METHODS

Among 647 patients, there were 159 receiving completion thyroidectomy for differentiated thyroid cancer (DTC) (Group 1); 217 patients receiving total thyroidectomy for DTC (Group 2) and 271 given total thyroidectomy for benign diseases (Group 3).

RESULTS

When groups were compared for complications, there were no significant difference except temporary hypocalcemia between completion thyroidectomy and total thyroidectomy for DTC. When the total thyroidectomies were compared (Group 2 and 3), there were no significant difference observed except unilateral temporary RLN palsy.

CONCLUSION

With improvements in surgical technique and experience, complication rates of thyroidectomy performed for benign or malign diseases are reduced. In spite of the improvement in surgical experience, temporary RLN palsy and hypoparathyroidism are the main complications in completion thyroidectomies which need special attention. To evaluate the patients more carefully in preoperative period and performing adequate thyroidectomy appears more logical.