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

ESTIMation of the ABiLity of prophylactic central compartment neck dissection to modify outcomes in low-risk differentiated thyroid cancer: a prospective randomized trial

BACKGROUND

Prophylactic central neck dissection in clinically low-risk cT1bT2N0 papillary thyroid carcinoma is controversial, due to a large number of conflicting retrospective studies, some showing an advantage in terms of locoregional recurrence, others showing no advantage. These previous studies all show high rates of excellent response. We aim to demonstrate the non-inferiority of thyroidectomy alone as compared to total thyroidectomy with prophylactic central neck dissection in conjunction with adjuvant RAI 30 mCi with rTSH stimulation in terms of excellent response at 1 year.

TRIAL DESIGN AND METHODS

Prospective randomized open multicenter phase III trial including patients with 11-40-mm papillary thyroid carcinoma (Bethesda VI) or suspicious cytology (Bethesda V) confirmed malignant on intra-operative frozen section analysis, with no suspicious lymph nodes on a specialized preoperative ultrasound examination. Patients will be randomized 1:1 into two groups: the reference group total thyroidectomy with bilateral prophylactic central neck dissection, and the comparator group total thyroidectomy alone. All patients will receive an ablative dose of 30mCi of radioactive iodine (RAI) within 4 months of surgery. The primary outcome is to compare the rate of excellent response at 1 year after surgery between the groups, as defined by an unstimulated serum thyroglobulin (Tg) level ≤ 0.2 ng/mL with no anti-Tg antibodies, an normal neck ultrasound and no ectopic uptake on the post-RAI scintiscan. Non-inferiority will be demonstrated if the rate of patients with excellent response at 1 year after randomization does not differ by more than 5%. Setting the significance level at 0.025 (one-sided) and a power of 80% requires a sample size of 598 patients (299 per group). Secondary outcomes are to compare Tg levels at 8 +/- 2 postoperative weeks, before RAI ablation, the rate of excellent response at 3 and 5 years, the rate of other responses at 1, 3, and 5 years (biochemical incomplete, indeterminate, and structurally incomplete responses), complications, quality of life, and cost-utility.

DISCUSSION (POTENTIAL IMPLICATIONS)

If non-inferiority is demonstrated with this high-level evidence, prophylactic neck dissection will have been shown to not be necessary in clinically low-risk papillary thyroid carcinoma.

TRIAL REGISTRATION

NCT03570021. June 26,2018.

Is Performance of Routine Central Compartment Neck Dissection in cN0 Papillary Thyroid Cancers Really Useful? 10-Year Prospective Observational Study

Central compartment nodes of neck are the first echelon nodes in papillary thyroid cancers (PTC). This study analyses the adverse parameters associated with central compartment nodal metastasis in cN0 PTC and also the usefulness of performing central compartment neck dissection routinely. A total of 236 patients with cNo PTC who underwent prophylactic central compartment neck dissection, from January 2008 to June 2017 in the Department of Oncology, Madurai Medical College, were included in study. Analysis of various adverse factors associated with central compartment nodal metastasis was made. Patients (46.18%) had metastatic nodes in the central compartment. Incidence of nodal metastasis increased with tumour size, capsular invasion, extrathyroidal extension, tracheal invasion and pulmonary metastasis. More than 50% patients did not have any of the statistically significant known adverse risk factors except for age and sex. Routine central compartment neck dissection has therapeutic value in PTC even in absence of known adverse factors and can be recommended in cases of clinically negative nodes. A meticulous dissection in experienced hands carries less complication rates as with thyroidectomy alone. In a resource limited country like ours, where the cost of re-surgery and radioiodine scans are high, a meticulous initial surgery incorporating central compartment neck dissection would really mean a difference.

Central Compartment Lymph Nodes Have Distinct Metastatic Patterns in Different Age Groups

BACKGROUND AND PURPOSE

Central compartment lymph node metastasis (CLNM) is a manifestation of tumor aggressiveness and an indicator of tumor prognosis. The purpose of this study was to construct a nomogram for evaluating CLNM patterns in papillary thyroid carcinoma (PTC) in different age groups.

METHOD

A total of 907 patients diagnosed with PTC from August 2014 to December 2018 were enrolled. A nomogram illustrating CLNM was generated using the results of multivariate logistic regression analysis.

RESULTS

According to the best Youden index, we set the cut-off age at 45 years. Multivariate logistic regression analysis showed that in patients aged <45 years, large tumor size (P<0.05), extra-thyroid extension (P<0.05) and thyroglobulin level >40 ng/ml (OR=2.985, 95% CI 1.379-6.462; P<0.05) were independent risk factors; meanwhile, Hashimoto's thyroiditis (OR=0.532, 95% CI 0.324-0.874; P<0.05) was a protective factor of CLNM. In the subgroup with age ≥45 years, large tumor size (P<0.05), extra-thyroid extension (P<0.05), unclear margin (OR=1.604, 95% CI 1.065-2.416; P<0.05), male gender (OR=2.009, 95% CI 1.257-3.212; P<0.05) were independent risk factors for CLNM. In the subgroup with age <45 years, an area under the curve (AUC) of 0.729 (95% CI 0.680-0.777); P<0.05) was obtained. In the ≥45 years subgroup, the AUC was 0.668 (95% CI 0.619-0.716; P<0.05).

CONCLUSION

CLNM of PTC in different age groups may have distinct patterns. Based on the potential risk factors for CLNM in patients with different age stratification, a user-friendly predictive model was established.

[De-escalation strategies in differentiated thyroid cancer]

Thyroid cancer runs the gamut from indolent micropapillary carcinoma to highly aggressive metastatic disease. Today, using prognostic algorithms, treatment and follow-up can be tailored to each patient in order to decrease overtreatment and over-medicalization of indolent disease. Active surveillance of papillary thyroid carcinoma less than 1cm avoids surgery and thyroid hormone replacement in a large proportion of patient whose tumors remain stable for years. Total thyroidectomy, once a dogma in the treatment of all thyroid cancer, is being supplanted by thyroid lobectomy for low-risk cancers, thereby decreasing the surgical risks involved and improving patients' quality of life. Indications for prophylactic central neck dissection, once mandatory, are now being adapted to the risk of cancer recurrence. Radioactive iodine therapy, also previously mandatory for all, is now only employed according to risk factors and expected outcomes. Follow-up is also being tailored to risk factors for recurrence, with less frequent visits and less use of ultrasound and scintigraphy. For more advanced disease, molecular therapies tailored to somatic mutations are opening opportunities for redifferentiation of aggressive tumors which become amenable to radioactive iodine therapy which carries fewer side effects than other systemic therapies. These advances in the management of thyroid cancer with a personalized approach and de-escalation of treatment and follow-up are improving the way we treat thyroid cancer, avoiding overtreatment and improving patients' quality of life.

Dual-energy computed tomography could reliably differentiate metastatic from non-metastatic lymph nodes of less than 0.5 cm in patients with papillary thyroid carcinoma

Background

Dual-energy computed tomography (DECT) has been widely applied to detect lymph node (LN) and lymph node metastasis (LNM) in various cancers, including papillary thyroid carcinoma (PTC). This study aimed to quantitatively evaluate metastatic cervical lymph nodes (LNs) <0.5 cm in patients with PTC using DECT, which has not been done in previous studies.

Methods

Preoperative DECT data of patients with pathologically confirmed PTC were retrospectively collected and analyzed between May 2016 and June 2018. A total of 359 LNs from 52 patients were included. Diameter, iodine concentration (IC), normalized iodine concentration (NIC), and the slope of the energy spectrum curve (λ_HU) of LNs in the arterial and the venous phases were compared between metastatic and non-metastatic LNs. The optimal parameters were obtained from the receiver operating characteristic (ROC) curves. The generalized estimation equation (GEE) model was used to evaluate independent diagnostic factors for LNM.

Results

A total of 139 metastatic and 220 non-metastatic LNs were analyzed. There were statistical differences of quantitative parameters between the two groups (P value 0.000-0.007). The optimal parameter for diagnosing LNM was IC in the arterial phase, and its area under the curve (AUC), sensitivity, and specificity were 0.775, 71.9%, and 73.6%, respectively. When the three parameters of diameter, IC in the arterial phase, and NIC in the venous phase were combined, the prediction efficiency was better, and the AUC was 0.819. The GEE results showed that LNs located in level VIa [odds ratio (OR) 2.030, 95% confidence interval (CI): 1.134-3.634, P=0.017], VIb (OR 2.836, 95% CI: 1.597-5.038, P=0.000), diameter (OR 2.023, 95% CI: 1.158-3.532, P=0.013), IC in the arterial phase (OR 4.444, 95% CI: 2.808-7.035, P=0.000), and IC in the venous phase (OR 5.387, 95% CI: 3.449-8.413, P=0.000) were independent risk factors for LNM in patients with PTC.

Conclusions

DECT had good diagnostic performance in the differentiation of cervical metastatic LNs <0.5 cm in patients with PTC.

The sentinel lymph node biopsy technique in papillary thyroid carcinoma: The issue of false-negative findings

BACKGROUND

The management of papillary thyroid carcinoma (PTC) is changed after introduction of sentinel lymph node biopsy (SNB) technique for nodal staging. Some debate still surrounds the accuracy of this procedure in terms of wide heterogeneity of sentinel lymph node detection and false-negative findings.

AIM

to identify the key issues which make it difficult the usefulness of SNB in PTC.

METHODS

A comprehensive computer literature search of meta-analyses published in PubMed/MEDLINE and Cochrane library database until June 30, 2019 was conducted. We used a search algorithm based on this combination of terms: (i) "thyroid neoplasm" or "thyroid cancer" or "thyroid carcinoma" or "thyroid malignancy" or "meta-analysis" or "systematic review") AND (ii) "sentinel lymph node biopsy".

RESULTS

Comparing 4 written meta-analyses published in the literature, the diagnostic performance of SNB technique in PTC has been summarized. Relatively high false-negative rates (FNR) were reported for each SNB methods: vital-dye (VD: 12.7%; 7%; 0-38%), 99mTc-nanocolloid planar lymphoscintigraphy with the use of intraoperative hand-held gamma probes (LS: 11.3%; 16%; 0-40%), combined LS with VD (LS+VD: 0%; 0-17%), LS with the additional contribution of preoperative SPECT/CT (7-8%).

CONCLUSION

Evidence-based data about the diagnostic performance of SNB in PTC are increasing. The nuclear medicine community should reach a consensus on the operational definition of the SLN to better guide the surgeon in identifying the lymph nodes most likely contain metastatic cells. Standardization of SLN identification, removal and analysis are required.

Effect of prophylactic central neck dissection on the surgical outcomes in papillary thyroid cancer: experience in a single center

PURPOSE

Morbidity due to papillary thyroid carcinoma (PTC) is increased mostly due to lymph node (LN) metastases, which lead to reoperations and complications associated with these operations. The aim is to compare the outcomes of PTC having total thyroidectomy and prophylactic central lymph node dissection (TT + PCND) with patients having total thyroidectomy (TT) alone.

METHODS

This study is a retrospective cohort analysis of 358 PTC patients that were operated by a single surgeon in a single center. Data about the patients were extracted from the medical records.

RESULTS

Of the patient cohort, 258 patients had TT + PCND (42.5 ± 11.3 years) and 100 patients (41.2 ± 11.9 years) had only TT. Total number of LN extracted in the TT + PCND group was 8.1 ± 6.9. The mean number of metastatic LN were 2.2 ± 1.9. Percentage of patients that had RAI were less in the TT + PCND group compared to the TT group. Seven patients (2.7%) in the TT + PCND group and 19 (19.0%) in TT group had recurrent disease (p < 0.0001). Of the complications, only transient hypoparathyroidism was increased in TT + PCND group compared to TT group (26.7% vs 10%, p < 0.0001).

CONCLUSION

TT + PCND performed by an experienced surgeon seems to decrease the number of LN recurrences, and the need for reoperations.

Carbon nanoparticles guide contralateral central neck dissection in patients with papillary thyroid cancer

The treatment of contralateral central neck lymph node metastasis is controversial in patients with papillary thyroid cancer. The present study reports the use of carbon nanoparticles (CNs) as lymph node tracers and discusses the potential role of predicting contralateral central neck metastasis is evaluated, so as to guide contralateral central neck dissection (CND). A total of 70 consecutive patients with papillary thyroid cancer were enrolled in the present study. All patients underwent a total or near-total thyroidectomy plus bilateral CND, during which CNs were used as a lymph node tracer. Of the 70 enrolled patients, 51 (72.86%) were confirmed to have lymph node metastasis in the central neck, 50 (71.43%) patients in the ipsilateral central neck and 14 (20.00%) in the contralateral central neck. A total of 579 (84.90%) lymph nodes were stained black by CNs. Of the 193 metastatic lymph nodes, 168 were located in the ipsilateral central compartment and the other 25 in the contralateral central compartment. A total of 147 (76.17%) metastatic lymph nodes were stained black. A total of 21 metastatic lymph nodes were found in the contralateral central compartment, 4 metastatic lymph nodes of contralateral central compartment were not black-stained. The sensitivity and specificity of CNs for contralateral metastasis was 84 and 25%, respectively. Contralateral central lymph node metastasis was significantly associated with extrathyroid extension and the presence of ipsilateral central neck lymph node metastasis. Together, the results of the present study reveal that CNs might accurately predict contralateral central lymph nodes metastasis and could be used to direct CND.

Rationality in prophylactic central neck dissection in clinically node-negative (cN0) papillary thyroid carcinoma: Is there anything more to say? A decade experience in a single-center

AIM

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy. Despite its extremely favorable prognosis, cervical lymph node metastases are a common feature of PTC and a known independent risk factor for local recurrence. However, the role of prophylactic central neck dissection (PCND) remains a matter of debate in patients with clinically node-negative (cN0) PTC. To better clarify the current role of PCND in the surgical treatment of PTC, evaluating advantages and disadvantages of PCND and outcome of cN0 PTC patients who have been treated with either total thyroidectomy alone or in combination with PCND. A review of recent literature data is performed.

METHODS

Between January 2000 and December 2015, 186 consecutive patients with cN0 PTC were identified to be included in the present study. 74 of these underwent total thyroidectomy associated with PCND, while 112 patients underwent total thyroidectomy alone. The epidemiological and clinical-pathological data of all patients included were collected at diagnosis and during follow-up.

RESULTS

Overall complication rate was significantly higher in the group of patients undergoing PCND (39.2% vs. 17.8%, p = 0.0006). To be specific, they presented a considerably increased risk of temporary recurrent laryngeal nerve injury (p = 0.009) and of permanent hypothyroidism (p = 0.016). Overall survival and recurrence rates did not differ between those undergoing PCND and those undergoing total thyroidectomy alone (p = 1.000 and p = 0.715, respectively).

CONCLUSIONS

The results of the present study do not support the routine use of PCND in the treatment of cN0 PTC patients.

Preliminary study on the diagnostic value of single-source dual-energy CT in diagnosing cervical lymph node metastasis of thyroid carcinoma

Background

To investigate the value of single-source dual-energy spectral CT imaging in improving the accuracy of preoperative diagnosis of lymph node metastasis of thyroid carcinoma.

Methods

Thirty-four thyroid carcinoma patients were enrolled and received spectral CT scanning before thyroidectomy and cervical lymph node dissection surgery. Iodine-based material decomposition (MD) images and 101 sets of monochromatic images from 40 to 140 keV were reconstructed after CT scans. The iodine concentrations (IC) of lymph nodes were measured on the MD images and was normalized to that of common carotid artery to obtain the normalized iodine concentration (NIC). The CT number of lymph nodes as function of photon energy was measured on the 101 sets of images to generate a spectral HU curve and to calculate its slope λ_HU. The measurements between the metastatic and non-metastatic lymph nodes were statistically compared and receiver operating characteristic (ROC) curves were used to determine the optimal thresholds of these measurements for diagnosing lymph nodes metastasis.

Results

There were 136 lymph nodes that were pathologically confirmed. Among them, 102 (75%) were metastatic and 34 (25%) were non-metastatic. The IC, NIC and the slope λ_HU of the metastatic lymph nodes were 3.93±1.58 mg/mL, 0.70±0.55 and 4.63±1.91, respectively. These values were statistically higher than the respective values of 1.77±0.71 mg/mL, 0.29±0.16 and 2.19±0.91 for the non-metastatic lymph nodes (all P<0.001). ROC analysis determined the optimal diagnostic threshold for IC as 2.56 mg/mL, with the sensitivity, specificity and accuracy of 83.3%, 91.2% and 85.3%, respectively. The optimal threshold for NIC was 0.289, with the sensitivity, specificity and accuracy of 96.1%, 76.5% and 91.2%, respectively. The optimal threshold for the spectral curve slope λ_HU was 2.692, with the sensitivity, specificity and accuracy of 88.2%, 82.4% and 86.8%, respectively.

Conclusions

The measurements obtained in dual-energy spectral CT improve the sensitivity and accuracy for preoperatively diagnosing lymph node metastasis in thyroid carcinoma.

Role of prophylactic central neck dissection in clinically node-negative differentiated thyroid cancer: assessment of the risk of regional recurrence

Prophylactic central neck dissection in clinically node-negative patients remains controversial. The aim of this multicenter retrospective study was to determine the rate of metastases in the central neck in clinically node-negative differentiated thyroid cancer patients, to examine the morbidity, and to assess the risk of regional recurrence in patients treated with total thyroidectomy with concomitant bilateral or ipsilateral central neck dissection compared with those undergoing total thyroidectomy alone. 258 consecutive clinically node-negative patients were divided into three groups according to the procedures performed: total thyroidectomy only (group A), total thyroidectomy with concomitant ipsilateral central neck dissection (group B), and total thyroidectomy combined with bilateral central neck dissection (group C). Mean operative time and postoperative stay were shorter in Group A (p < 0.01). The incidence of postoperative transient hypoparathyroidism was lower in Group A (p = 0.03), whereas no differences in the incidence of permanent hypoparathyroidism and nerve palsy were present. Postoperative radioactive iodine administration was higher in group B and particularly C (p = 0.03) compared with group A. There were no statistically significant differences in terms of regional recurrence. Differentiated thyroid cancer has a high rate of central lymph node metastasis even in clinically node-negative patients; in the present study there was no statistically significant difference in the rates of locoregional recurrence between the three modalities of treatment. Total thyroidectomy appears to be an adequate treatment for clinically node-negative differentiated thyroid cancer. Prophylactic central neck dissection might be considered for differentiated thyroid cancer patients with large tumor size or extrathyroidal extension.

Recombinant human thyrotropin-stimulated thyroglobulin level at the time of radioactive iodine ablation is an independent prognostic marker of differentiated thyroid carcinoma in the setting of prophylactic central neck dissection

OBJECTIVE

We investigated the value of the stimulated thyroglobulin (Tg) level at the time of recombinant human thyrotropin (rhTSH)-aided remnant ablation for predicting disease status 1 year later in patients with DTC who underwent total thyroidectomy with central neck dissection (CND).

DESIGN, SETTING, AND PARTICIPANT

This was a prospective observational study of 253 consecutive patients with DTC who underwent rhTSH-aided RAI ablation after total thyroidectomy and prophylactic CND. Patients with evidence of initial distant metastasis or positive Tg antibodies were excluded.

MAJOR OUTCOME MEASURE

We compared rhTSH-stimulated Tg level at RAI ablation according to the disease status at 1 year and evaluated optimal cut-off value of rhTSH-stimulated Tg. Binary logistic regression analysis was performed to investigate the independent predictive factors for disease status 1 year after ablation.

RESULTS

Among study participants, 228 (90·1%) were considered disease free at 1 year after remnant ablation. Patients with persistent or recurrent disease were more likely to be aged ≥45 years, and to have N1b stage, TNM stage III or IV, and higher rhTSH-stimulated Tg level at RAI ablation. The optimal cut-off of rhTSH-stimulated Tg for predicting persistent or recurrent disease was 1·79 ng/ml, with a negative predictive value of 99·5%. A serum rhTSH-stimulated Tg level ≥1·79 at the time of ablation was independently associated with persistent or recurrent disease 1 year later. N1b stage tended to be associated with persistent or recurrent disease.

CONCLUSION

A low stimulated serum Tg level at rhTSH-aided RAI ablation may be a favourable prognostic marker in the setting of prophylactic CND.

Pattern of nodal involvement in papillary thyroid cancer: a challenge of quantitative analysis

INTRODUCTION

Backgrounds of this study were to examine and analyse the relationship among the number of lymph nodes with metastases harvested in central and lateral compartments, the characteristics of tumours and patients, and the recurrences rate.

METHODS

A retrospective review of 118 patients treated for a papillary thyroid cancer and underwent to neck dissection, including in all cases both central and lateral compartment, was realised. A quantitative analysis, on this homogeneous cohort of patients, was performed to hypothesize the minimum number of cervical lymph nodes to be necessarily excised in order to obtain an adequate management of these patients.

RESULTS

The mean follow-up time was 75.9 months. Five-year overall survival was 96.6%. The correlation among the metastatic lymph node number of the ipsilateral central compartment, isolated or pooled with those of the ipsilateral lateral compartment, age of patient and tumour size revealed a statistical significance (P=0.01); both parameters, tumour size and age, may be considered as dependent predictor variables.

CONCLUSION

We suppose, notwithstanding the limited number of patients, that the number of lymph nodes harvested to achieve an optimal cervical dissection may be superior to 8 and 11 in central and lateral compartments, and 6 and 10 in contralateral ones, respectively. Moreover we recommend the bilateral dissection of central nodes compartment in presence of tumour localised in the isthmus.