Management of the central compartment in differentiated thyroid carcinoma

Incidental Node Metastasis as an Independent Factor of Worse Disease-Free Survival in Patients with Papillary Thyroid Carcinoma

INTRODUCTION

Papillary thyroid carcinoma (PTC) have high node metastasis rates. Occasionally after thyroidectomy, the pathological report reveals node metastasis unintentionally resected. The present study aimed to evaluate the prognosis of these patients.

METHODS

A retrospective cohort of patients submitted to thyroidectomy with or without central compartment neck dissection (CCND) due to PTC with a minimum follow-up of five years.

RESULTS

A total of 698 patients were included: 320 Nx, 264 pN0-incidental, 37 pN1a-incidental, 32 pN0-CCND and 45 pN1a-CCND. Patients with node metastasis were younger, had larger tumors, higher rates of microscopic extra-thyroidal extension, and angiolymphatic invasion and most received radioiodine therapy. Treatment failure was higher in patients pN1a-incidental and pN1a-CCND (32% and 16%, respectively; p < 0.001-Chi-square test). Disease-free survival (DFS) was lower in patients pN1a-incidental compared to patients Nx and pN0-incidental (p < 0.001 vs. Nx and pN0-incidental and p = 0.005 vs. pN0-CCND) but similar when compared to patients pN1a-CCND (p = 0.091)-Log-Rank test. Multivariate analysis demonstrated as independent risk factors: pT4a (HR = 5.524; 95%CI: 1.380-22.113; p = 0.016), pN1a-incidental (HR = 3.691; 95%CI: 1.556-8.755; p = 0.003), microscopic extra-thyroidal extension (HR = 2.560; 95%CI: 1.303-5.030; p = 0.006) and angiolymphatic invasion (HR = 2.240; 95%CI: 1.077-4.510; p = 0.030).

CONCLUSION

Patients that were pN1a-incidental were independently associated with lower DFS.

Differentiated thyroid cancer theranostics: radioiodine and beyond

The term theranostics is the combination of a diagnostic tool that helps to define the right therapeutic tool for specific disease. It signifies the "we know which sites require treatment (diagnostic scan) and confirm that those sites have been treated (post-therapy scan)" demonstrating the achievable tumor dose concept. This term was first used by John Funkhouser at the beginning of the 90s, at the same time the concept of personalized medicine appeared. In nuclear medicine, theranostics is easy to apply and understand because of an easy switch from diagnosis to therapy with the same vector. It helps in maximizing tumor dose and sparing normal tissue with high specific and rapid uptake in metastasis. The oldest application of this concept is radioactive iodine I-131 (RAI). The first treatment based on the theranostic concept was performed on thyroid cancer patients with RAI in 1946. From then on management of differentiated thyroid cancer (DTC) has evolved on the multimodality concept. We now use the term "our" patient instead of "my" patient to signify this. However, the initial surgical management followed by RAI as per the theranostics has remained the mainstay in achieving a cure in most of DTC patients. The normal thyroid cells metabolise iodine, the principle of which is utilized in imaging of the thyroid gland with isotopes of iodine. RAI treatment of DTC is based on the principle of sodium iodide symporter (NIS) expressing thyroid cells with DTC cells having the ability of trapping circulating RAI successfully helping in treatment of residual and metastatic disease. NIS is usually negative in poorly differentiated cells and is inversely proportional to Glucose transporter receptor Type 1 expression. Both positive and negative NIS are the key components of the theranostic approach in treatment of DTC. Presence or absence of NIS is documented by either whole body iodine scintigraphy (WBS) or 2-deoxy-2(18F) fludeoxyglucose (FDG) positron emission tomography computed tomography (PET-CT). Currently, single photon emission CT and CT (SPECT-CT) has significantly improved the precision and sensitivity of whole body iodine scintigraphy with its capability of accurate localization of disease foci whether iodine avid or non-avid. This has helped in a more personalized approach in treatment. This review will give an overview of the role of NIS in the theranostic approach to management with RAI, its current status and also the molecular approach to treatment in RAI refractory disease.

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.

Management of differentiated thyroid carcinomas

INTRODUCTION AND OBJECTIVES

Radioiodine is the principal treatment for differentiated thyroid carcinomas. The aim of this study is to present our experience in the management of these tumours.

MATERIAL AND METHOD

We present a retrospective study of 55 patients operated for differentiated thyroid carcinoma in our hospital between 2007 and 2011.

RESULTS

The mean age at time of diagnosis was 49 years, and females predominated (78% of cases). Seventy eight percent of the patients were in the initial stages (stages i and ii). The definitive histopathological diagnosis was papillary carcinoma in 84% and follicular carcinoma in the remaining 16%. All of the patients, with the exception of 2 (4%), underwent total thyroidectomy, with lymphadenectomy in 58% of cases. Nine percent of the patients had permanent hypoparathyroidism and although 18% suffered transitory unilateral paralysis, 40% of these female patients had completely recovered after 6 months. Eighty-nine percent of the patients were given radioiodine postoperatively. There was a recurrence rate of 40% most of which was at cervical level (29% of the patients). Survival at 5 years was 87%, 95% of the papillary subtype, falling to 56% of the follicular subtype (P=.001).

DISCUSSION/CONCLUSIONS

The prognosis for differentiated thyroid carcinomas is excellent after appropriate surgical treatment, thorough preoperative assessment,and strict postoperative follow-up due to the significant recurrence rates.