The pros and cons of routine central compartment neck dissection for clinically nodal negative (cN0) papillary thyroid cancer

Frozen section analysis of central lymph nodes in papillary thyroid cancer: the significance in determining the extent of surgery

BACKGROUND

The indolent feature of papillary thyroid cancer (PTC) has recently led to an increase in less aggressive treatment options instead of total thyroidectomy (TT). We aimed to investigate the clinical significance of elective central compartment neck dissection (CCND) with intraoperative frozen analyses of the central lymph nodes (LNs) to determine the surgical extent of unilateral clinically node-negative PTC.

METHODS

We retrospectively reviewed the medical records of 290 patients with unilateral clinically node-negative PTC who underwent surgery and performed frozen analyses of the central LNs from 2020 to 2021 using our own nodal criteria with cut-off size 5 mm. The patients were divided and investigated according to the surgical extent and the National Comprehensive Cancer Network (NCCN) guidelines; diagnostic accuracy of the frozen analyses was estimated.

RESULTS

TT was performed in 16.2% of patients. The TT group had more metastatic nodes with a larger size, higher LN ratio (LNR), and more extranodal extension. The analyses based on the NCCN guidelines showed similar findings, but more completion TT was required compared with our criteria. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the frozen analyses were 94.6%, 100%, 100%, and 96.1%, respectively.

CONCLUSIONS

Elective CCND with intraoperative frozen analyses is a highly reliable procedure that detects occult nodal metastasis in unilateral node-negative PTC patients. Our nodal criteria yielded significant aggressive nodal characteristics in the TT group while yielding less TTs compared with the NCCN guidelines. The concept and clinical significance of small-volume nodal metastasis in PTC should be further investigated.

[Three-dimensional reconstruction of cervical CT vs ultrasound for estimating residual thyroid volume]

OBJECTIVE

To compare the accuracy of three-dimensional reconstruction of cervical CT and ultrasound for estimating residual thyroid volume.

METHODS

We performed a retrospective analysis of 17 patients with 21 residual thyroid glands undergoing thyroidectomy surgery between February, 2017 and March, 2018 in our department. We compared the residual thyroid volume in preoperative ultrasound with the intraoperative measurement and the volume measured using threedimensional CT reconstruction before surgery.

RESULTS

The maximum vertical and anterioposterior diameters of the residual thyroid measured by preoperative ultrasound differed significantly from the volume data measured intraoperatively (P < 0.05), but the difference in the maximum left-right diameters was not statistically significant (P>0.05). The maximum vertical, leftright, and anteroposterior diameters estimated by three-dimensional reconstruction of cervical CT was all similar with those measured intraoperatively (P>0.05).

CONCLUSIONS

Compared with ultrasound examination, three-dimensional reconstruction of neck CT is more accurate for estimating the residual thyroid volume and provides more reliable evidence for clinical calculation of postoperative I131 dose for thyroid cancer.

Identification of Tissue-Specific DNA Methylation Signatures for Thyroid Nodule Diagnostics

PURPOSE

Thyroid cancer is frequently difficult to diagnose due to an overlap of cytologic features between malignant and benign nodules. This overlap leads to unnecessary removal of the thyroid in patients without cancer. While providing some improvement over cytopathologic diagnostics, molecular methods frequently fail to provide a correct diagnosis for thyroid nodules. These approaches are based on the difference between cancer and adjacent thyroid tissue and assume that adjacent tissues are the same as benign nodules. However, in contrast to adjacent tissues, benign thyroid nodules can contain genetic alterations that can be found in cancer.Experimental Design: For the development of a new molecular diagnostic test for thyroid cancer, we evaluated DNA methylation in 109 thyroid tissues by using genome-wide single-base resolution DNA methylation analysis. The test was validated in a retrospective cohort containing 65 thyroid nodules.

RESULTS

By conducting reduced representation bisulfite sequencing in 109 thyroid specimens, we found significant differences between adjacent tissue, benign nodules, and cancer. These tissue-specific signatures are strongly linked to active enhancers and cancer-associated genes. Based on these signatures, we developed a new epigenetic approach for thyroid diagnostics. According to the validation cohort, our test has an estimated specificity of 97% [95% confidence interval (CI), 81-100], sensitivity of 100% (95% CI, 87-100), positive predictive value of 97% (95% CI, 83-100), and negative predictive value of 100% (95% CI, 86-100).

CONCLUSIONS

These data show that epigenetic testing can provide outstanding diagnostic accuracy for thyroid nodules.See related commentary by Mitmaker et al., p. 457.

Morbidity of central neck dissection for papillary thyroid cancer

Thyroid cancer has a very well-known propensity for nodal involvement, either in the central and lateral neck compartments. Neck dissection addressing the central compartment may be performed with an elective or therapeutic intent, the former concomitantly to a thyroidectomy whereas the latter may be accomplished also as a revision procedure for recurrent disease. In this paper complications of central compartment neck dissection will be described, analyzing separately primary and revision procedures.

Are there disparities in the presentation, treatment and outcomes of patients diagnosed with medullary thyroid cancer?-An analysis of 634 patients from the California Cancer Registry

BACKGROUND

Race, gender and socioeconomic disparities have been suggested to adversely influence stage at presentation, treatment options and outcomes in patients with cancer. Underserved minorities and those with a low socioeconomic status (SES) present with more advanced disease and have worse outcomes for differentiated thyroid cancer, but this relationship has never been evaluated for medullary thyroid cancer (MTC).

METHODS

We used the California Cancer Registry (CCR) to evaluate disparities in the presentation, treatment and outcomes of patients diagnosed with MTC.

RESULTS

We identified 634 patients with MTC diagnosed between 1988 and 2011. Almost everyone (85%) underwent thyroidectomy with 50% having a central lymph node dissection (CLND). There were no statistically significant differences by age, race or SES in mean tumor size or the proportion of patients diagnosed with localized disease, but men were diagnosed with larger tumors than women and were less likely to be diagnosed at a localized stage. Younger patients and women were more likely to be treated with a thyroidectomy. There were no statistically significant differences in surgical treatment by race or SES. Patients in the highest SES category had a better overall survival, but not disease specific survival, than those in the lowest SES (HR =0.3, CI =0.1-0.7). Patients treated with thyroidectomy had a better overall and cause specific survival, but the effect of CLND was not statistically significant after adjustment for other factors.

CONCLUSIONS

In MTC, we did not find that race, gender or SES influenced the presentation, treatment or outcomes of patients with MTC. Men with MTC present with larger tumors and are less likely to have localized disease. Half of the MTC patients in California do not undergo a CLND at the time of thyroidectomy, which may suggest a lack appropriate care across a range of healthcare systems.

To Identify Predictors of Central Lymph Node Metastasis in Patients with Clinically Node-Negative Conventional Papillary Thyroid Carcinoma

Objective. The aim of this study was to identify the risk factors associated with central lymph node metastasis (CLNM) in patients with clinically node-negative conventional papillary thyroid carcinoma (cN₀ CPTC). Methods. A total of 190 cN₀ CPTC patients who underwent thyroidectomy with prophylactic central neck dissection (pCND) in the Department of General Surgery at Guangdong General Hospital between March 2014 and December 2015 were assessed retrospectively. The relations of CLNM with clinicopathologic characteristics of cN₀ CPTC were analyzed by univariate and multivariate logistic regression. Results. The incidence of CLNM in patients with cN₀ CPTC was 63.2% (120 of 190 cases). Univariate analysis showed that age <45 years (P = 0.000), tumor size >2 cm (P = 0.009), multifocality (P = 0.001), and bilaterality (P = 0.000) were significantly associated with the increased incidence of CLNM in cN₀ CPTC. No significant correlations were found between CLNM and other variables such as gender (P = 0.150), capsular invasion (P = 0.973), extrathyroidal invasion (P = 0.616), and lymphadenectomy (P = 0.062). Multivariate logistic regression analysis revealed that age <45 years (P = 0.000), tumor size >2 cm (P = 0.025), and bilaterality (P = 0.000) were independent risk factors of CLNM in patients with cN₀ CPTC. Conclusions. Metastatic disease to central compartment lymph nodes is prevalent in patients with cN₀ CPTC. Age <45 years, tumor size >2 cm, and bilaterality are independent risk factors of CLNM, which allow for selective CND in patients with cN₀ CPTC.

Impact of prophylactic central neck dissection on oncologic outcomes of papillary thyroid carcinoma: a review

Prophylactic neck dissection (PND) for papillary thyroid carcinoma (PTC) is controversial. Our aim was to assess current levels of evidence (LE) according to the Oxford Centre for Evidence-based Medicine ( http://www.cebm.net/?O=1025 ) regarding the oncologic benefits of PND. Data were analyzed via MEDLINE keywords: PTC, differentiated thyroid carcinoma, PND, central lymph node metastases, central compartment, recurrence-free survival. There was conflicting evidence regarding the rate of reoperation for recurrence, with some studies showing a lower rate after PND with increased recurrence-free survival and a higher rate of undetectable pre- and post-ablation thyroglobulin levels (LE 4), whereas other studies did not show a difference (LE 4). Only one study (LE 4) showed improved disease-specific survival with PND. PND may improve recurrence-free survival, although this is supported by only a low LE. Current recommendations can only be based on low-level evidence.