The effect of extent of surgery and number of lymph node metastases on overall survival in patients with medullary thyroid cancer

Disease-free survival and the prognostic factors affecting disease-free survival in patients with medullary thyroid carcinoma: a multicenter cohort study

PURPOSE

Despite several factors that may have been associated with poor disease-free survival (DFS) in patients with medullary thyroid carcinoma (MTC), only a few studies have evaluated the prognostic factors affecting DFS in MTC patients. Therefore, this study evaluated the prognostic factors affecting DFS, in a large number of patients with MTC.

METHODS

Patients treated for MTC were retrospectively analyzed. Patients were stratified as having persistent/recurrent disease and no evidence of disease (NOD) at the last follow-up. The factors affecting DFS after the initial therapy and during the follow-up period were investigated.

RESULTS

This study comprised 257 patients [females 160 (62.3%), hereditary disease 48 (18.7%), with a mean follow-up time of 66.8 ± 48.5 months]. Persistent/recurrent disease and NOD were observed in 131 (51%) and 126 (49%) patients, respectively. In multivariate analysis, age > 55 (HR: 1.65, p = 0.033), distant metastasis (HR: 2.41, p = 0.035), CTN doubling time (HR: 2.7, p = 0.031), and stage III vs. stage II disease (HR 3.02, p = 0.048) were independent predictors of persistent/recurrent disease. Although 9 (8%) patients with an excellent response after the initial therapy experienced a structural recurrence, the absence of an excellent response was the strongest predictor of persistent/recurrent disease (HR: 5.74, p < 0.001).

CONCLUSIONS

The absence of an excellent response after initial therapy is the strongest predictor of a worse DFS. However, a significant proportion of patients who achieve an excellent response could experience a structural recurrence. Therefore, careful follow-up of patients, including those achieving an excellent response is essential.

Well-defined survival outcome disparity across age cutoffs at 45 and 60 for medullary thyroid carcinoma: a long-term retrospective cohort study of 3601 patients

Background

Medullary thyroid cancer (MTC) is a challenging malignancy. The survival outcome of MTC based on AJCC staging system does not render a discriminant classifier among early stages.

Methods

3601 MTC patients from 2000 to 2018 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Smooth curve fitting, Cox proportional hazard regression and competing risk analysis were applied.

Results

A linear correlation between age and log RR (relative risk of overall death) was detected. Overlaps were observed between K-M curves representing patients aged 45-50, 50-55, and 55-60. The study cohort was divided into 3 subgroups with 2 age cutoffs set at 45 and 60. Each further advanced age cutoff population resulted in a roughly "5%" increase in MTC-specific death risks and an approximately "3 times" increase in non-MTC-specific death risks.

Conclusions

The survival outcome disparity across age cutoffs at 45 and 60 for MTC has been well defined.

Axillary Node Metastases of Medullary Thyroid Cancer: A Hallmark of Terminal Disease

Little is known about axillary node metastasis of medullary thyroid cancer (MTC). To address this, a comparative study of patients with and without axillary node metastases of MTC was conducted. Among 1215 consecutive patients with MTC, 482 patients had node-negative MTC and 733 patients node-positive MTC. Among the 733 patients with node-positive MTC, 4 patients (0.5%) had axillary node metastases, all of which were ipsilateral. Patients with axillary node metastases had 5.7-6.9-fold more node metastases removed, both at the authors' institution (medians of 34.5 vs. 5 metastases; p=0.011) and in total (medians of 57 vs. 10 metastases; p=0.013), developed more frequently distant metastases (3 of 4 vs. 178 of 729 patients, or 75 vs. 24%; p=0.049), specifically to bone (2 of 4 vs. 67 of 729 patients, or 50 vs. 9%; p=0.046) and brain (1 of 4 vs. 4 of 729 patients, or 25 vs. 0.5%; p=0.027), and more often succumbed to cancer-specific death (3 of 4 vs. 52 of 729 patients, or 75 vs. 14%; p=0.005). Altogether, patients with axillary node metastases revealed 4-8-fold more node metastases in the ipsilateral lateral neck (medians of 11 vs. 3 metastases; p=0.021) and in the ipsilateral central neck (medians of 8 vs. 1 metastases; p=0.079) patients without axillary node metastases. Cancer-specific survival of patients with vs. patients without axillary node metastases of MTC was significantly shorter (means of 41 vs. 224 months; plog-rank<0.001). These findings show that patients with axillary node metastases of MTC have massive metastatic dissemination with poor survival.

Extent of Surgery for Medullary Thyroid Cancer and Prevalence of Occult Contralateral Foci

Importance

Standard treatment for patients with medullary thyroid cancer (MTC) consists of total thyroidectomy with central neck dissection, but the rationale for bilateral surgery in patients with unilateral disease on ultrasonography remains unclear.

Objective

To determine the presence of occult contralateral disease (lesions not seen on preoperative ultrasonography) in patients with MTC as a rationale for total thyroidectomy.

Design, Setting, and Participants

This multi-institutional, retrospective cohort study was conducted from September 1998 to April 2022 in academic medical centers and included patients with MTC who underwent thyroidectomy with preoperative imaging.

Main Outcomes and Measures

The primary end point was the prevalence of sonographically occult foci of MTC in the contralateral lobe among patients with sporadic MTC.

Results

The cohort comprised 176 patients with a median age at diagnosis of 55 years (range, 2-87 years), 69 (57.6%) of whom were female. Genetic testing was performed in 109 patients (61.9%), 48 (27.5%) of whom carried germline RET variants. Initial surgical management consisted of total thyroidectomy (161 [91.0%]), lobectomy followed by completion thyroidectomy (7 [4.0%]), and lobectomy alone (8 [4.5%]). Central and lateral neck dissections were performed as part of initial therapy for 146 patients (83.1%). In the entire cohort of 176 patients, 46 (26.0%) had contralateral foci disease and 9 (5.1%) had occult contralateral foci that were not identified on preoperative ultrasonography. Among 109 patients who underwent genetic testing, 38 (34.9%) had contralateral disease, 8 (7.3%) of whom had occult contralateral disease not seen on preoperative ultrasonography. Patients with sporadic MTC experienced a 95.7% reduction in the odds of having a focus of MTC in the contralateral lobe compared with patients with a germline RET variant (odds ratio, 0.043; 95% CI, 0.013-0.123). When adjusting for age, sex, tumor size, and lymph node involvement, the odds ratio of having contralateral MTC in patients with sporadic disease was 0.034 (95% CI, 0.007-0.116). Among patients who underwent lobectomy alone with postoperative calcitonin levels, 5 of 12 (41.7%) achieved undetectable calcitonin levels (<2.0 pg/mL; to convert to pmol/L, multiply by 0.292).

Conclusions and Relevance

The results of this cohort study suggest that a staged approach involving initial thyroid lobectomy could be considered in patients with sporadic MTC and no contralateral ultrasonography findings, with no further surgery if calcitonin levels became undetectable. Further work using prospective randomized clinical trials to evaluate lobectomy as a biochemical cure in patients presenting with unilateral disease is warranted.

A Proposed Modified Staging System for Medullary Thyroid Cancer: A SEER Analysis With Multicenter Validation

BACKGROUND

The 8th edition of the American Joint Committee on Cancer (AJCC) staging system for medullary thyroid cancer (MTC) was implemented in 2018. However, its ability to predict prognosis remains controversial.

PATIENTS AND METHODS

Patient data were obtained from the Surveillance, Epidemiology, and End Results (SEER) database and multicenter datasets. Overall survival was the primary end-point of the present study. The concordance index (C-index) was used to assess the efficacy of various models to predict prognostic outcomes.

RESULTS

A total of 1450 MTC patients were selected from the SEER databases and 349 in the multicenter dataset. According to the AJCC staging system, there were no significant survival differences between T4a and T4b categories (P = .299). The T4 category was thus redefined as T4a' category (≤3.5 cm) and T4b' category (>3.5 cm) based on the tumor size, which was more powerful for distinguishing the prognosis (P = .003). Further analysis showed that the T category was significantly associated with both lymph node (LN) location and count (P < .001). Therefore, the N category was modified by combining the LN location and count. Finally, the above-mentioned novel T and N categories were adopted to modify the 8th AJCC classification using the recursive partitioning analysis principle, and the modified staging system outperformed the current edition (C-index, 0.811 vs. 0.792).

CONCLUSIONS

The 8th AJCC staging system was improved based on the intrinsic relationship among the T category, LN location, and LN count, which would have a positive impact on the clinical decision-making process and appropriate surveillance.

Competing-risks model for predicting the prognostic value of lymph nodes in medullary thyroid carcinoma

BACKGROUND

Medullary thyroid carcinoma (MTC) is an infrequent form malignant tumor with a poor prognosis. Because of the influence of competitive risk, there may suffer from bias in the analysis of prognostic factors of MTC.

METHODS

By extracting the data of patients diagnosed with MTC registered in the Surveillance, Epidemiology, and End Results (SEER) database from 1998 to 2016, we established the Cox proportional-hazards and competing-risks model to retrospectively analyze the impact of related factors on lymph nodes statistically.

RESULTS

A total of 2,435 patients were included in the analysis, of which 198 died of MTC. The results of the multifactor competing-risk model showed that the number of total lymph nodes (19-89), positive lymph nodes (1-10,11-75) and positive lymph node ratio (25%-53%,>54%), age (46-60,>61), chemotherapy, mode of radiotherapy (others), tumor size(2-4cm,>4cm), number of lesions greater than 1 were poor prognostic factors for MTC. For the number of total lymph nodes, unlike the multivariate Cox proportional-hazards model results, we found that it became an independent risk factor after excluding competitive risk factors. Competitive risk factors have little effect on the number of positive lymph nodes. For the proportion of positive lymph nodes, we found that after excluding competitive risk factors, the Cox proportional-hazards model overestimates its impact on prognosis. The competitive risk model is often more accurate in analyzing the effects of prognostic factors.

CONCLUSIONS

After excluding the competitive risk, the number of lymph nodes, the number of positive and the positive proportion are the poor prognostic factors of medullary thyroid cancer, which can help clinicians more accurately evaluate the prognosis of patients with medullary thyroid cancer and provide a reference for treatment decision-making.

Validation of miRNAs as diagnostic and prognostic biomarkers, and possible therapeutic targets in medullary thyroid cancers

Introduction

Medullary thyroid cancer (MTC) is a rare type of neuroendocrine tumor that produces a hormone called calcitonin (CT). Thyroidectomy is the preferred treatment for MTC, as chemotherapy has been shown to have limited effectiveness. Targeted therapy approaches are currently being used for patients with advanced, metastatic MTC. Several studies have identified microRNAs, including miR-21, as playing a role in the development of MTC. Programmed cell death 4 (PDCD4) is a tumor suppressor gene that is an important target of miR-21. Our previous research has shown that high levels of miR-21 are associated with low PDCD4 nuclear scores and high CT levels. The aim of this study was to investigate the potential of this pathway as a novel therapeutic target for MTC.

Methods

We used a specific process to silence miR-21 in two human MTC cell lines. We studied the effect of this anti-miRNA process alone and in combination with cabozantinib and vandetanib, two drugs used in targeted therapy for MTC. We analyzed the effect of miR-21 silencing on cell viability, PDCD4 and CT expression, phosphorylation pathways, cell migration, cell cycle, and apoptosis.

Results

Silencing miR-21 alone resulted in a reduction of cell viability and an increase in PDCD4 levels at both mRNA and protein levels. It also led to a reduction in CT expression at both mRNA and secretion levels. When combined with cabozantinib and vandetanib, miR-21 silencing did not affect cell cycle or migration but was able to enhance apoptosis.

Conclusion

Silencing miR-21, although not showing synergistic activity with TKIs (tyrosine kinase inhibitors), represents a potential alternative worth exploring as a therapeutic target for MTC.

A Contemporary Review of the Treatment of Medullary Thyroid Carcinoma in the Era of New Drug Therapies

Medullary thyroid cancer (MTC) is a rare neuroendocrine tumor that can be sporadic or inherited and is often associated with mutations in the RET (Rearranged during Transfection) oncogene. The primary treatment for MTC is surgical resection of all suspected disease, but recent advances in targeted therapies for MTC, including the selective RET inhibitors selpercatinib and pralsetinib, have led to changes in the management of patients with locally advanced, metastatic, or recurrent MTC. In this article, we review updates on the evaluation and management of patients with MTC, focusing on new and emerging therapies that are likely to improve patient outcomes.

Guideline Adherence and Practice Patterns in the Management of Medullary Thyroid Cancer

INTRODUCTION

Little is known about nationwide practice patterns for the management medullary thyroid cancer (MTC) in relation to the 2015 American Thyroid Association guidelines and their impact on survival.

METHODS

Using the Surveillance, Epidemiology, and End Results Program database (2000-2018), MTC treatment patterns were evaluated in terms of adherence to the 2015 American Thyroid Association guidelines across three time periods (2000-2009, 2010-2015, and 2016-2018). Outcomes of interest were guideline concordance, treatment utilization trends, disease-specific survival (DSS), and overall survival (OS).

RESULTS

A total of 3332 patients with MTC were identified. Of which, 53.8%, 33.2%, and 11.4% of patients had localized, regional, and distant disease, respectively. In patients with locoregional disease, the rate of guideline-concordant surgery improved over time from 63.0% in 2000-2009 to 76.0% in 2016-2018 (P < 0.001). Guideline-concordant care was associated with increased OS (HR = 1.85, 95% CI: 1.42-2.43, P < 0.001) in patients with localized disease and increased DSS (HR = 1.65, 95% CI: 1.01-2.54, P < 0.001) and OS (HR = 1.89, 95% CI: 1.35-2.58, P < 0.001) in patients with regional disease. The median OS and DSS in patients with distant disease were 31 and 55 mo, respectively, and the rate of chemotherapy use rose from 21.6% to 39.2% (P = 0.003).

CONCLUSIONS

The rate of guideline-concordant surgery for locoregional MTC increased after guideline publication in 2015, with an observed prolongment in OS and DSS. Chemotherapy use among patients with distant disease has increased over time, but their prognosis remains variable.

A novel prognostic model based on log odds of positive lymph nodes to predict outcomes of patients with anaplastic thyroid carcinoma after surgery

OBJECTIVE

The eighth version of the American Joint Committee on Cancer (8th AJCC) system for anaplastic thyroid carcinoma (ATC) added lymph node (LN) metastasis as the staging element. This study aimed to explore the association between LN status and ATC's prognosis, identify the optimal LN index and establish a novel prognostic model.

DESIGN AND PATIENTS

Data of 199 ATC patients after surgery were collected from the Surveillance, Epidemiology and End Results (SEER) database, then randomly divided into training and validation cohorts.

MEASUREMENTS

We compared the prognostic value of AJCC N status, number of positive LN (PLNN), ratio of LN (LNR) and log odds of positive LN (LODDS). We conducted univariate and multivariate Cox analyses to determine the independent prognostic factors for ATC, and constructed a novel prognostic model. The concordance index (C-index), area under the receiver-operating characteristic curve (AUC), calibration curves and decision curve analysis (DCA) were used to assess the nomogram's predictive performance.

RESULTS

LODDS showed the highest accuracy among four LN systems to predict overall survival (OS) for ATC. In the training cohort, the C-index of the LODDS-based nomogram was 0.738. The AUCs were 0.813, 0.850 and 0.869 for predicting 1-, 2- and 3-year OS, respectively. The calibration plots and DCA indicated the great clinical applicability of the model. The above results were verified in the validation cohort.

CONCLUSIONS

LODDS showed better predictive performance than other LN schemes in ATC. The LODDS-incorporated nomogram has the potential to more precisely predict the prognosis for ATC patients than the AJCC system.

Total thyroidectomy vs thyroid lobectomy for localized medullary thyroid cancer in adults: A propensity-matched survival analysis

BACKGROUND

This study aimed to clarify whether the extent of thyroidectomy (total thyroidectomy vs thyroid lobectomy) influences survival in adults with localized medullary thyroid cancer.

METHODS

Patients with localized medullary thyroid cancer were identified using the Surveillance, Epidemiology, and End Results database (2000-2018). An independent cohort of patients with localized medullary thyroid cancer were retrospectively reviewed from three medical centers in China from 2010 to 2020. The patients were grouped by the extent of surgery (total thyroidectomy vs thyroid lobectomy). Primary end points were overall survival and disease-specific survival.

RESULTS

From 1,686 patients with medullary thyroid cancer identified in SEER, 1,122 patients met inclusion for matching, with a median follow-up of 99 months. After propensity score matching, 122 patients underwent a total thyroidectomy and 122 patients underwent a thyroid lobectomy. The 10-year overall survival was 85.2% (77.9%-90.7%) and 83.1% (75.5%-90.7%) in total thyroidectomy group and in thyroid lobectomy group, respectively. The 10-year disease-specific survival was 100% and 96.8% (93.1%-100%) in total thyroidectomy group and in thyroid lobectomy group, respectively. There was no statistically significant difference in overall survival or disease-specific survival in patients with localized medullary thyroid cancer undergoing total thyroidectomy or thyroid lobectomy (hazard ratio = 0.83, 95% confidence interval 0.44-1.57, P = .57 and hazard ratio = 0.49, 95% confidence interval 0.10-2.41, P = .39, respectively). Forty-seven patients with localized medullary thyroid cancer were identified in an independent Chinese cohort (n = 29 in total thyroidectomy group vs n = 18 in thyroid lobectomy group). After a median follow-up of 47 months, there was no mortality observed in either group.

CONCLUSION

This study suggests that the extent of thyroidectomy does not influence survival for patients with early-stage localized medullary thyroid cancer and that thyroid lobectomy might be adequate in this patient population.

Somatostatin receptor-directed molecular imaging for therapeutic decision-making in patients with medullary thyroid carcinoma

BACKGROUND

Somatostatin receptor (SSTR) positron emission tomography/computed tomography (PET/CT) is increasingly deployed in the diagnostic algorithm of patients affected with medullary thyroid carcinoma (MTC). We aimed to assess the role of SSTR-PET/CT for therapeutic decision making upon restaging.

METHODS

23 pretreated MTC patients underwent SSTR-PET/CT and were discussed in our interdisciplinary tumor board. Treatment plans were initiated based on scan results. By comparing the therapeutic regimen before and after the scan, we assessed the impact of molecular imaging on therapy decision. SSTR-PET was also compared to CT portion of the SSTR-PET/CT (as part of hybrid imaging).

RESULTS

SSTR-PET/CT was superior in 9/23 (39.1%) subjects when compared to conventional CT and equivalent in 14/23 (60.9%). Those findings were further corroborated on a lesion-based level with 27/73 (37%) metastases identified only by functional imaging (equivalent to CT in the remaining 46/73 (63%)). Investigating therapeutic decision making, no change in treatment was initiated after PET/CT in 7/23 (30.4%) patients (tyrosine kinase inhibitor (TKI), 4/7 (57.2%); surveillance, 3/7 (42.8%)). Imaging altered therapy in the remaining 16/23 (69.6%). Treatment prior to PET/CT included surgery in 6/16 (37.5%) cases, followed by TKI in 4/16 (25%), active surveillance in 4/16 (25%), and radiation therapy (RTx) in 2/16 (12.5%) subjects. After SSTR-PET/CT, the therapeutic regimen was changed as follows: In the surgery group, 4/6 (66.7%) patients underwent additional surgery, and 1/6 (16.7%) underwent surveillance and TKI, respectively. In the TKI group, 3/4 (75%) individuals received another TKI and the remaining subject (1/4, 25%) underwent peptide receptor radionuclide therapy. In the surveillance group, 3/4 (75%) underwent surgery (1/4, (25%), RTx). In the RTx group, one patient was switched to TKI and another individual was actively monitored (1/2, 50%, respectively). Moreover, in the 16 patients in whom treatment was changed by molecular imaging, control disease rate was achieved in 12/16 (75%) during follow-up.

CONCLUSIONS

In patients with MTC, SSTR-PET/CT was superior to CT alone and provided relevant support in therapeutic decision-making in more than two thirds of cases, with most patients being switched to surgical interventions or systemic treatment with TKI. As such, SSTR-PET/CT can guide the referring treating physician towards disease-directed treatment in various clinical scenarios.

Superiority of metastatic lymph node ratio over number of node metastases and TNM/AJCC N classification in predicting cancer-specific survival in medullary thyroid cancer

BACKGROUND

In medullary thyroid cancer (MTC), it is unclear which nodal classification system, metastatic lymph node ratio (MLNR), number of node metastases, or TNM/AJCC N classification, predicts cancer-specific survival best.

METHODS

Kaplan-Maier analysis of cancer-specific survival after operation at a tertiary center.

RESULTS

Included were 505 MTC patients. The spread of the survival curves was greatest after stratification by MLNR (in 0.20 increments), followed by number of node metastases (in 10-node and 20-node increments) and TNM/AJCC classification (N0, N1a, N1b). After collapsing overlapping survival curves, all adjacent curves (MLNRs ≤0.20 vs. 0.21-0.60 vs. >0.60; 0 vs. 1-20 vs. >20 node metastases; and TNM/AJCC N classification N0/N1a vs. N1b) significantly differed between each other.

CONCLUSIONS

In MTC, MLNR, reflecting intensity of lymphatic spread, predicts cancer-specific survival better than number of node metastases or TNM/AJCC N classification. The applicability of these findings to patients with limited neck dissection requires more research.

Preoperative Identification of Medullary Thyroid Carcinoma (MTC): Clinical Validation of the Afirma MTC RNA-Sequencing Classifier

Background: Cytopathological evaluation of thyroid fine-needle aspiration biopsy (FNAB) specimens can fail to raise preoperative suspicion of medullary thyroid carcinoma (MTC). The Afirma RNA-sequencing MTC classifier identifies MTC among FNA samples that are cytologically indeterminate, suspicious, or malignant (Bethesda categories III-VI). In this study we report the development and clinical performance of this MTC classifier. Methods: Algorithm training was performed with a set of 483 FNAB specimens (21 MTC and 462 non-MTC). A support vector machine classifier was developed using 108 differentially expressed genes, which includes the 5 genes in the prior Afirma microarray-based MTC cassette. Results: The final MTC classifier was blindly tested on 211 preoperative FNAB specimens with subsequent surgical pathology, including 21 MTC and 190 non-MTC specimens from benign and malignant thyroid nodules independent from those used in training. The classifier had 100% sensitivity (21/21 MTC FNAB specimens correctly called positive; 95% confidence interval [CI] = 83.9-100%) and 100% specificity (190/190 non-MTC FNAs correctly called negative; CI = 98.1-100%). All positive samples had pathological confirmation of MTC, while all negative samples were negative for MTC on surgical pathology. Conclusions: The RNA-sequencing MTC classifier accurately identified MTC from preoperative thyroid nodule FNAB specimens in an independent validation cohort. This identification may facilitate an MTC-specific preoperative evaluation and resulting treatment.

Incidental T1 stage medullary thyroid carcinoma: The effect of tumour diameter on prognosis and therapeutic implications

OBJECTIVE

The definition of the tumour diameter of micro-medullary thyroid carcinoma (micro-MTC) is insufficient. It is controversial to perform a completion thyroidectomy immediately for incidental T1 stage MTC.

DESIGN

We used the Surveillance, Epidemiology and End Results (SEER) registry to retrospectively analyze all patients with T1 stage MTC diagnosed between 2004 and 2015. The tumour diameter 1.0 and 0.5 cm were used as the cut-off points to group and analyze the differences of clinicopathological features. We analyzed the prognosis of patients with less than total thyroidectomy.

METHODS

The disease-specific survival was the main outcome. Survival was estimated with Kaplan-Meier curves and Cox regression models estimated hazard ratios for tumour characteristics.

RESULTS

A total of 908 patients diagnosed with T1 stage MTC in the SEER database were included. Our study found that tumour diameter 1.0 cm is a key point affecting the prognosis of T1 stage MTC patients, although patients with tumour diameter ≤ 0.5 cm had a lower rate of lymph node metastasis and no distant metastasis. Cox proportional hazard multivariate analysis showed that distant metastasis was the only risk factor for survival in patients with T1 stage MTC. Kaplan-Meier survival analysis showed that, regardless of tumour diameter, there was no significant difference between less than total thyroidectomy and total thyroidectomy in T1 stage patients.

CONCLUSIONS

For incidental MTC with tumour diameter ≤ 1.0 cm and without distant metastasis, if there is no significant increase in serum calcitonin level after surgery and ret proto-oncogene (RET) gene mutation is negative, it may be not necessary to perform completion thyroidectomy immediately.

Novel Therapeutics and Treatment Strategies for Medullary Thyroid Cancer

Medullary thyroid cancer is a rare thyroid malignancy with unique management considerations. In general, small intrathyroidal tumors are cured by total thyroidectomy with central compartment dissection, while large tumors and those with disease spread to regional lymph nodes and distant organs (most commonly lung, liver, and bone) are more difficult to cure. The last decade has seen significant progress in the treatment of advanced MTC, largely due to the discovery and availability of novel targeted therapies, including new drugs specifically targeting the RET protooncogone.

Inclusion of the Number of Metastatic Lymph Nodes in the Staging System for Medullary Thyroid Cancer: Validating a Modified American Joint Committee on Cancer Tumor-Node-Metastasis Staging System

Background: The current American Joint Committee on Cancer (AJCC) staging system (8th edition) for medullary thyroid cancer (MTC) was originally extrapolated from the staging system for differentiated thyroid cancer. However, the current staging system does not accurately predict the prognosis of patients with MTC. Patients and Methods: The present study was based on data from the Surveillance, Epidemiology, and End Results (SEER) database and validated by multicenter data from the Shanghai Tenth People's Hospital, Tongji University School of Medicine, Xuzhou City Central Hospital, and Suzhou Ninth People's Hospital. Hazard ratio with its 95% confidence interval [CI] was estimated by Cox proportional hazards regression analysis. The concordance index (C-index) was used to evaluate the discrimination accuracy of the current AJCC tumor-node-metastasis (TNM) staging system and the modified AJCC (mAJCC) TNM staging system. Results: A total of 1175 MTC patients were selected from the SEER database and 312 from the three hospitals in China. We redefined the N category according to the number of metastatic lymph nodes (LNs) as follows: N'0 category (0 metastatic LNs), N'1 category (1-9 metastatic LNs), and N'2 category (≥10 metastatic LNs). The four distinct tumor stages were reclassified in the mAJCC staging system as follows: stage I (T1-4N'0M0, T1N'1M0), stage II (T2-3N'1M0, T1N'2M0), stage III (T4N'1M0, T2-4N'2M0), and stage IV (TanyN'anyM1). The C-index of the current AJCC staging system and the mAJCC staging system was 0.72 [CI, 0.67-0.78] and 0.78 [CI, 0.73-0.84], respectively. Similar results were observed in the survival analysis of the multicenter data set. Conclusions: The mAJCC staging system could discriminate the prognosis of MTC patients more effectively than the current AJCC staging system, indicating that it is feasible and appropriate to modify the current AJCC staging system by introducing the number of metastatic LNs instead of the location of LNs. These findings might be adopted in the next edition of the AJCC staging system and be used to guide clinical practice.

Lobectomy may be more appropriate for patients with early-stage medullary thyroid cancer older than 60 years old

PURPOSE

Clinical guidelines presently recommend total thyroidectomy for the treatment of medullary thyroid cancer (MTC). This study was aimed to investigate whether lobectomy could be the initial treatment for stage I MTC patients.

METHODS

The retrospective study was based on data from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. The risk factors of survival were estimated by the univariate and multivariate Cox proportional-hazards model. The effect of age on death risk was estimated using restricted cubic splines. Survival curves were constructed according to the Kaplan-Meier method.

RESULTS

A total of 988 stage I MTC patients was included in the study. Among them, 506 (51.2%) MTC patients received lobectomy and 482 (48.8%) received total thyroidectomy. The only independent prognostic factor for overall survival (OS) and disease-specific survival (DSS) was age, according to univariate and multivariate Cox regression analysis. The hazard ratio (HR) increased relatively slowly with age growing under the age of approximately 60 years. However, the death risk of MTC patients began to rise sharply with increasing age above 60 years. For patients under the age of 60, a significant survival difference for OS and DSS was observed between the lobectomy group and total thyroidectomy group (p < 0.05). However, for patients aged above 60, no significant survival difference was observed for OS or DSS (p > 0.05).

CONCLUSION

Total thyroidectomy was an appropriate treatment for stage I MTC patients under the age of 60, which was consistent with the recommendation of the clinical guidelines. However, for those over the age of 60, lobectomy may be explored as a better surgical option. The findings may provide the evidence base for improving the clinical management of stage I MTC patients. Further prospective multicenter clinical studies are needed including information regarding RET status as well as calcitonin and CEA levels.

Metastatic Lymph Node Ratio for Predicting Recurrence in Medullary Thyroid Cancer

Simple Summary

The anatomical staging system for thyroid cancer only contains categories for lymph node compartments. The metastatic lymph node ratio (LNR), which is the ratio of metastasized lymph nodes to the total number of evaluated lymph nodes, is suggested as a quantitative evaluation tool for lymph node metastasis in patients with medullary thyroid cancer in this study. The initial stratification implemented in this study was helpful in predicting structural recurrence, and LNR was identified as a predictor of disease-free survival.

Abstract

The lymph node ratio (LNR) has been investigated as a prognostic factor in many different types of cancers, including differentiated thyroid cancer; however, reports regarding medullary thyroid cancer (MTC) are limited. Therefore, this study aims to evaluate LNR as a risk factor for structural recurrence in patients with MTC. Medical records of patients treated for MTC in a single tertiary center between 1995 and 2017 were retrospectively reviewed. LNR is defined as the number of metastatic lymph nodes or lymph node metastases (LNM) divided by the number of retrieved lymph nodes or lymph node yield (LNY). In the survival analysis, recurrence-free survival was defined as the time from the date of total thyroidectomy to recurrence or last follow-up. To identify risk factors influencing structural recurrence, univariable and multivariable Cox proportional hazard models were used. A total of 132 patients were enrolled. The mean age of study participants was 49.7 years, and 86 patients (65%) were women. Structural recurrence was identified in 39 patients at the end of the study period, and the median follow-up period was 8.7 years. In univariable analyses, gross extra thyroidal extension, N stage, postoperative serum calcitonin and carcinoembryonic antigen (CEA) levels, and LNR were significant (p < 0.05) predictors of structural recurrence. In multivariable analysis, postoperative serum calcitonin, postoperative serum CEA, and LNR were identified as a predictor of disease-free survival (p < 0.05). LNR can potentially predict structural recurrence as a quantitative evaluation tool for lymph node metastasis in patients with MTC.

Capsular extension at ultrasound is associated with lateral lymph node metastasis in patients with papillary thyroid carcinoma: a retrospective study

BACKGROUND

In patients with papillary thyroid cancer (PTC), cervical lymph node metastasis (LNM) must be carefully assessed to determine the extent of lymph node dissection required and patient prognosis. Few studies attempted to determine whether the ultrasound (US) appearance of the primary thyroid tumor could be used to predict cervical lymph node involvement. This study aimed to identify the US features of the tumor that could predict cervical LNM in patients with PTC.

METHODS

This was a retrospective study of patients with pathologically confirmed PTC. We evaluated the following US characteristics: lobe, isthmus, and tumor size; tumor position; parenchymal echogenicity; the number of lesions (i.e., tumor multifocality); parenchymal and lesional vascularity; tumor margins and shape; calcifications; capsular extension; tumor consistency; and the lymph nodes along the carotid vessels. The patients were grouped as no LNM (NLNM), central LNM (CLNM) alone, and lateral LNM (LLNM) with/without CLNM, according to the postoperative pathological examination.

RESULTS

Totally, 247 patients, there were 67 men and 180 women. Tumor size of > 10 mm was significantly more common in the CLNM (70.2%) and LLNM groups (89.6%) than in the NLNM group (45.4%). At US, capsular extension > 50% was most common in the LLNM group (35.4%). The multivariable analysis revealed that age (OR = 0.203, 95%CI: 0.095-0.431, P < 0.001) and tumor size (OR = 2.657, 95%CI: 1.144-6.168, P = 0.023) were independently associated with CLNM compared with NLNM. In addition, age (OR = 0.277, 95%CI: 0.127-0.603, P = 0.001), tumor size (OR = 6.069, 95%CI: 2.075-17.75, P = 0.001), and capsular extension (OR = 2.09, 95%CI: 1.326-3.294, P = 0.001) were independently associated with LLNM compared with NLNM.

CONCLUSION

Percentage of capsular extension at ultrasound is associated with LLNM. US-guided puncture cytology and eluent thyroglobulin examination could be performed as appropriate to minimize the missed diagnosis of LNM.

Abandoning node dissection for desmoplasia-negative encapsulated unifocal sporadic medullary thyroid cancer

BACKGROUND

Predictive criteria to determine the absence of node metastases from thyroid specimens are scarce for sporadic medullary thyroid cancer.

METHODS

Histopathologic stratification of patients with unifocal sporadic medullary thyroid cancer ≤25 mm with ≥10 neck nodes at thyroidectomy to evaluate the suitability of desmoplasia (7 increments) and tumor capsule integrity (5 decrements) for intraoperative prediction of node metastasis in unifocal sporadic medullary thyroid cancer.

RESULTS

Paraffin-embedded thyroid specimens were available for 139 eligible patients. Significant (P < .001) associations were found between increasing desmoplasia and decreasing tumor capsule integrity and nodal disease (from 0 to 79% and 0 to 62%); the number of node metastases (medians, from 0 to 3 and 0 to 2 nodes); and biochemical cure (from 100 to 36% and 100 to 58%). Desmoplasia (low-moderate to high, with fibrosis >10%) and breach of the tumor capsule (>3 extensions; 1 extension >3 mm in width; or diffuse growth without tumor capsule) yielded excellent sensitivity and negative predictive value (100%), with moderate specificity (57 and 48%) and positive predictive value (50 and 46%). In retrospect, node dissection proved unnecessary in 55 (57%) and 47 (48%) patients who harbored desmoplasia-negative and encapsulated tumors. When available frozen sections were histopathologically compared with matching paraffin-embedded thyroid tumor specimens, concordance was 98% (53 of 54 pairs): 1 of 7 upgrades changed the diagnosis to desmoplasia, whereas 1 of 3 downgrades shifted the diagnosis of tumor capsule breach from "present" to "absent."

CONCLUSIONS

Patients with desmoplasia-negative encapsulated sporadic medullary thyroid cancer may forgo node dissection at specialist centers.

Metastatic Risk Profile of Microscopic Lymphatic and Venous Invasion in Medullary Thyroid Cancer

The metastatic risk profile of microscopic lymphatic and venous invasion in medullary thyroid cancer is ill-defined. This evidence gap calls for evaluation of the suitability of microscopic lymphatic and venous invasion at thyroidectomy for prediction of lymph node and distant metastases in medullary thyroid cancer. In this study of 484 patients with medullary thyroid cancer who had≥5 lymph nodes removed at initial thyroidectomy, microscopic lymphatic and venous invasion were significantly associated with greater primary tumor size (27.6 vs. 14.5 mm, and 30.8 vs. 16.2 mm) and more frequent lymph node metastasis (97.0 vs. 25.9%, and 85.2 vs. 39.5%) and distant metastasis (25.0 vs. 5.1%, and 32.8 vs. 7.3%). Prediction of lymph node metastases by microscopic lymphatic invasion was better than prediction of distant metastases by microscopic venous invasion regarding sensitivity (97.0 vs. 32.8%) and positive predictive value (58.4 vs. 39.2%); comparable regarding negative predictive value (98.5 vs. 90.5%) and accuracy (80.4 vs. 85.1%); and worse regarding specificity (74.1 vs. 92.7%). On multivariable logistic regression, microscopic lymphatic invasion predicted lymph node metastasis better (odds ratio [OR] 65.6) than primary tumor size (OR 4.6 for tumors>40 mm and OR 2.7 for tumors 21-40 mm, relative to tumors≤20 mm), whereas primary tumor size was better in predicting distant metastasis (OR 8.3 for tumors>40 mm and OR 3.9 for tumors 21-40 mm, relative to tumors≤20 mm) than microscopic venous invasion (OR 3.2). These data show that lymphatic invasion predicts lymph node metastases better in medullary thyroid cancer than venous invasion heralds distant metastases.

Medullary thyroid cancer outcomes in patients with undetectable versus normalized postoperative calcitonin levels

BACKGROUND

Calcitonin (Ct) is a sensitive diagnostic biomarker and one of the most important prognostic factors in medullary thyroid cancer (MTC). This study aimed to evaluate progression-free survival and recurrence rates of MTC associated with undetectable compared with normalized serum Ct levels after surgery.

METHODS

This retrospective observational study included patients operated for MTC at the Digestive and Endocrine Surgery Department of Lyon Sud Hospital Centre between 2000 and 2019. Clinical and pathological factors were correlated with postoperative Ct concentrations. Undetectable and normalized Ct concentrations were defined as below 2 pg/ml and 2-10 pg/ml respectively.

RESULTS

Overall, 176 patients were treated for MTC, and 127 were considered biochemically cured after surgery. Of these, 24 and 103 had normalized and undetectable Ct concentrations respectively. Patients with Ct level normalization had a 25 per cent risk of disease recurrence, compared with 3 per cent in patients with undetectable Ct levels after surgery. The presence of metastasis in two or more compartments was predictive of failure to achieve undetectable Ct concentrations after surgery and an increased risk of recurrence.

CONCLUSION

Among patients with biochemically cured MTC, those with undetectable or normalized Ct concentrations after surgery had different risks of recurrence. Simply assessing postoperative Ct normalization can be falsely reassuring, and long-term follow-up is needed.

Construction and Validation of a Nomogram Based on the Log Odds of Positive Lymph Nodes to Predict the Prognosis of Medullary Thyroid Carcinoma After Surgery

BACKGROUND

This study aimed to explore the prognostic impact that the log odds of positive lymph nodes (LODDS) has on medullary thyroid cancer (MTC) and to develop a nomogram incorporating LODDS to predict the cancer-specific survival (CSS) of MTC.

METHODS

Data from 1110 MTC patients after total thyroidectomy were collected from the Surveillance, Epidemiology, and End Results (SEER) database and divided into training and validation cohorts. The prognostic efficiency of N status from the American Joint Committee on Cancer (AJCC) staging system, the number of positive lymph nodes (PLNN), and LODDS were compared using the Harrell concordance index (C-index), the Akaike information criterion (AIC), and area under the receiver operating characteristic (ROC) curve (AUC). A multivariate Cox analysis was performed to determine the independent prognostic factors, and a nomogram based on LODDS was constructed. The nomogram's performance was assessed with the C-index, AUC, calibration curves, and decision curve analysis (DCA).

RESULTS

Among the three lymph node (LN) staging systems, LODDS showed the highest accuracy in predicting CSS for MTC. In the training cohort, the C-index of the LODDS-based nomogram was 0.895. The AUCs were 0.949, 0.917, 0.925, and 0.901 for predicting 1-, 3-, 5- and 10-year CSS, respectively. The calibration plots and DCA showed the superior clinical applicability of the nomogram. These results were verified in the validation cohort.

CONCLUSIONS

As an independent prognostic factor for MTC, LODDS demonstrated superior prognostic efficiency over N status and PLNN. This LODDS-based nomogram yielded better performance than the AJCC tumor-node-metastasis (TNM) staging system in predicting CSS after surgery for MTC.

Initial treatment of patients with thyroid cancer: Outcomes and factors associated with care at academic versus nonacademic cancer centers

BACKGROUND

Factors associated with receiving initial care for thyroid cancer (TC) at academic centers (ACs) versus nonacademic centers (NACs) and their impact on patient outcomes have not been reported.

METHODS

The National Cancer Database with TC cases from 2004 to 2013 was evaluated for association of type of center for initial care with socioeconomic factors and disease and treatment characteristics, as well as overall survival (OS; all-cause mortality).

RESULTS

The patients with TC (n = 200,824) included were predominantly women (74%), non-Hispanic Whites (85%), and from metro areas (84%). Sixty percent received initial care at a NAC. There were no significant differences between treatment groups by age or gender. Among those treated at an AC, a higher proportion belonged to racial/ethnic minorities (16.5%) versus at a NAC (11.6%). Hormone therapy was used more in an AC versus a NAC (60% vs 47%). Patients with all TC pathologies combined had a lower likelihood of death when they received initial care at an AC (hazard ratio [HR], 0.948; P = .0006). Among individual pathologic subtypes, a lower likelihood of death was noted when initial care was received at an AC for follicular (HR, 0.828, P = .0010) and Hurthle cell cancers (HR, 792; P = .0008), as well as stage II papillary thyroid cancer (HR, 0.828; P = .0026), but not for other histopathologic subtypes.

CONCLUSIONS

Initial care at an AC was associated with lower likelihood of death for patients with TC, especially for those with follicular or Hurthle cell subtypes. Optimal resource use with consideration of patients' socioeconomic and demographic factors is imperative to ensure the most appropriate management of patients with TC in various treatment settings.

Limitations of preoperative cytology for medullary thyroid cancer: Proposal for improved preoperative diagnosis for optimal initial medullary thyroid carcinoma specific surgery

BACKGROUND

Preoperative diagnosis of medullary thyroid carcinoma (MTC) is often difficult, given the poor sensitivity of fine-needle aspiration (FNA) cytology for MTC. This study investigates this issue and presents recommendations for improving preoperative diagnostic paradigms in MTC cases.

DESIGN/METHOD

Histopathologically confirmed MTC patients with preoperative cytologic assessment of index nodules were enrolled. FNA diagnosis, final pathology, and surgery details were collected.

RESULTS

Out of 71 patients, 49 (69%) were diagnosed by FNA as either definitive MTC (35, 49%) or suspected MTC (14, 20%) and 22 (31%) patients had no indication of MTC on FNA.

CONCLUSION

In a tertiary-care setting, one-third of subjects had an FNA interpretation that did not suggest the possibility of MTC. The limitations of preoperative diagnosis are especially problematic for MTC as they can cause delayed or incomplete treatment. Additional testing is proposed to improve preoperative diagnosis and surgical care of MTC patients.

Association between age and disease specific mortality in medullary thyroid cancer

BACKGROUND

The aim of this study was to evaluate the association between age and disease specific mortality (DSM) among adults diagnosed with medullary thyroid cancer (MTC).

METHOD

Surveillance, Epidemiology, and End Results (SEER-18) was used to analyze adult MTC patients stratified by age (18-64, 65-79, ≥80 years). Associations between patient demographics, tumor size, nodal status, metastatic disease, and extent of surgery on DSM was assessed with multivariable Cox regression.

RESULTS

Among 1457 patients with MTC, 1008 (69.2%) were younger adults, 371 (25.5%) older adults, and 78 (5.4%) were super-elderly. A significantly higher proportion of older adults and super-elderly had less than the recommended operation for MTC. On multivariable analysis, older adults and super-elderly were 2.9 and 6.7 times more likely to have an increased DSM (HR:2.91, 95% CI: 1.83-4.63; p < 0.001 and HR: 6.70, 95%CI: 3.69-12.20; p < 0.001). Extent of surgery or lymphadenectomy did not affect DSM.

CONCLUSIONS

Increased age is an independent predictor of DSM in patients with MTC.

Risk Factors for Lateral Lymph Node Metastases in Patients With Sporadic Medullary Thyroid Carcinoma

PURPOSE

Medullary thyroid carcinoma is a rare endocrine malignancy; 75% of patients with this disease have sporadic medullary thyroid carcinoma. While surgery is the only curative treatment, the benefit of prophylactic lateral neck dissection is unclear. This study aimed to analyze the clinicopathological risk factors associated with lateral lymph node metastases and determine the indication for prophylactic lateral neck dissection in patients with sporadic medullary thyroid carcinoma.

METHODS

The medical records of patients with medullary thyroid carcinoma who were treated at our hospital between January 2002 and January 2020 were retrospectively reviewed; a database of their demographic characteristics, test results, and pathological information was constructed. The relationship between lateral lymph node metastases and clinicopathologic sporadic medullary thyroid carcinoma features were analyzed using univariate and multivariate analyses.

RESULTS

Overall, 125 patients with sporadic medullary thyroid carcinoma were included; 47.2% and 39.2% had confirmed central and lateral lymph node metastases, respectively. Univariate and multivariate analyses identified 2 independent factors associated with lateral lymph node metastases: positive central lymph node metastases (odds ratio = 9.764, 95% confidence interval: 2.610-36.523; p = 0.001) and positive lateral lymph nodes on ultrasonography (odds ratio = 101.747, 95% confidence interval: 14.666-705.869; p < 0.001).

CONCLUSION

Medullary thyroid carcinoma is a rare endocrine malignancy. Lymph node metastases are common in patients with sporadic medullary thyroid carcinoma. Prophylactic lateral neck dissection is recommended for patients who exhibit positive central lymph node metastases and/or positive lateral lymph nodes on ultrasonography.

Cabozantinib and vandetanib for unresectable locally advanced or metastatic medullary thyroid cancer: a systematic review and economic model

BACKGROUND

Medullary thyroid cancer (MTC) is a rare form of cancer that affects patients' health-related quality of life (HRQoL) and survival. Cabozantinib (Cometriq^®; Ipsen, Paris, France) and vandetanib (Caprelsa^®; Sanofi Genzyme, Cambridge, MA, USA) are currently the treatment modality of choice for treating unresectable progressive and symptomatic MTC.

OBJECTIVES

(1) To evaluate the clinical effectiveness and safety of cabozantinib and vandetanib. (2) To estimate the incremental cost-effectiveness of cabozantinib and vandetanib versus each other and best supportive care. (3) To identify key areas for primary research. (4) To estimate the overall cost of these treatments in England.

DATA SOURCES

Peer-reviewed publications (searched from inception to November 2016), European Public Assessment Reports and manufacturers' submissions.

REVIEW METHODS

A systematic review [including a network meta-analysis (NMA)] was conducted to evaluate the clinical effectiveness and safety of cabozantinib and vandetanib. The economic analysis included a review of existing analyses and the development of a de novo model.

RESULTS

The systematic review identified two placebo-controlled trials. The Efficacy of XL184 (Cabozantinib) in Advanced Medullary Thyroid Cancer (EXAM) trial evaluated the efficacy and safety of cabozantinib in patients with unresectable locally advanced, metastatic and progressive MTC. The ZETA trial evaluated the efficacy and safety of vandetanib in patients with unresectable locally advanced or metastatic MTC. Both drugs significantly improved progression-free survival (PFS) more than the placebo (p < 0.001). The NMA suggested that, within the symptomatic and progressive MTC population, the effects on PFS were similar (vandetanib vs. cabozantinib: hazard ratio 1.14, 95% credible interval 0.41 to 3.09). Neither trial demonstrated a significant overall survival benefit for cabozantinib or vandetanib versus placebo, although data from ZETA were subject to potential confounding. Both cabozantinib and vandetanib demonstrated significantly better objective response rates and calcitonin (CTN) and carcinoembryonic antigen (CEA) response rates than placebo. Both cabozantinib and vandetanib produced frequent adverse events, often leading to dose interruption or reduction. The assessment group model indicates that, within the EU-label population (symptomatic and progressive MTC), the incremental cost-effectiveness ratios (ICERs) for cabozantinib and vandetanib are > £138,000 per quality-adjusted life-year (QALY) gained. Within the restricted EU-label population (symptomatic and progressive MTC with CEA/CTN doubling times of ≤ 24 months), the ICER for vandetanib is expected to be > £66,000 per QALY gained. The maximum annual budget impact within the symptomatic and progressive population is estimated to be ≈£2.35M for cabozantinib and ≈£5.53M for vandetanib. The costs of vandetanib in the restricted EU-label population are expected to be lower.

LIMITATIONS

The intention-to-treat populations of the EXAM and ZETA trials are notably different. The analyses of ZETA subgroups may be subject to confounding as a result of differences in baseline characteristics and open-label vandetanib use. Attempts to statistically adjust for treatment switching were unsuccessful. No HRQoL evidence was identified for the MTC population.

CONCLUSIONS

The identified trials suggest that cabozantinib and vandetanib improve PFS more than the placebo; however, significant OS benefits were not demonstrated. The economic analyses indicate that within the EU-label population, the ICERs for cabozantinib and vandetanib are > £138,000 per QALY gained. Within the restricted EU-label population, the ICER for vandetanib is expected to be > £66,000 per QALY gained.

FUTURE RESEARCH PRIORITIES

(1) Primary research assessing the long-term effectiveness of cabozantinib and vandetanib within relevant subgroups. (2) Reanalyses of the ZETA trial to investigate the impact of adjusting for open-label vandetanib use using appropriate statistical methods. (3) Studies assessing the impact of MTC on HRQoL.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016050403.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Thyroid Disease in Adults

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate thyroidectomy.

BACKGROUND

Surgical management of thyroid disease has evolved considerably over several decades leading to variability in rendered care. Over 100,000 thyroid operations are performed annually in the US.

METHODS

The medical literature from 1/1/1985 to 11/9/2018 was reviewed by a panel of 19 experts in thyroid disorders representing multiple disciplines. The authors used the best available evidence to construct surgical management recommendations. Levels of evidence were determined using the American College of Physicians grading system, and management recommendations were discussed to consensus. Members of the American Association of Endocrine Surgeons reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines analyze the indications for thyroidectomy as well as its definitions, technique, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Fine Needle Aspiration Biopsy Diagnosis, Molecular Testing, Indications, Extent and Outcomes of Surgery, Preoperative Care, Initial Thyroidectomy, Perioperative Tissue Diagnosis, Nodal Dissection, Concurrent Parathyroidectomy, Hyperthyroid Conditions, Goiter, Adjuncts and Approaches to Thyroidectomy, Laryngology, Familial Thyroid Cancer, Postoperative Care and Complications, Cancer Management, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal surgical management of thyroid disease.

Thyroid cancer histological subtypes based on tumor size: National perspective

BACKGROUND

Thyroid tumor size is an important prognostic factor. The aim of this study is to examine the histological subtypes and management of thyroid cancer based on tumor size (≤4 cm vs >4 cm).

METHODS

Retrospective cohort study utilizing the National Cancer Database, 2004-2014.

RESULTS

A total of 152 387 patients were included, 13 614 (8.9%) of whom had a tumor size >4 cm. Histological subtypes of tumors >4 cm were: 69.6% papillary thyroid carcinoma, 17.5% FTC, 7.9% HCC, and 2.8% medullary thyroid carcinoma (MTC). High-volume hospitals for thyroid surgery were less likely to perform two-stage thyroidectomy, particularly for tumors ≤4 cm. Low-volume hospitals had a higher risk of staged thyroidectomy for MTC ≤4 cm (19.8%) compared with high-volume hospitals (8.7%) (P < .001).

CONCLUSIONS

This study describes the prevalence of thyroid cancer subtypes. In the era of a conservative approach to differentiated thyroid carcinoma, there could be a potential increase in the risk of staged thyroidectomy.

Prediction of biochemical cure in patients with medullary thyroid cancer

BACKGROUND

The impact of number of node metastases versus metastatic lymph node ratio versus AJCC node category on biochemical cure in medullary thyroid cancer (MTC) is not well defined.

METHODS

Multivariable logistic regression analysis was used to determine clinical and histopathological variables that contribute to biochemical cure in node-positive MTC.

RESULTS

Some 584 of 1026 patients with MTC underwent systematic lymph node dissections for node-positive disease; 27·4 per cent (54 of 197) were biochemically cured after the initial operation and 13·5 per cent (42 of 310 patients) after repeat surgery. Cured patients had significantly less extrathyroid extension (11-14 versus 33·2-55·6 per cent), fewer lymph node metastases (median 2-4 versus 12-16), a lower metastatic lymph node ratio (median 0·05-0·08 versus 0·23-0·28), and were less likely to have AJCC pN1b disease (56-76 versus 89·9-91·6 per cent) and distant metastases (0 versus 28·4-37·1 per cent) than patients who were not cured. Biochemical cure curves advanced steadily up to 7-12 node metastases and a metastatic lymph node ratio of 0·33, eventually levelling off after 16-17 node metastases and metastatic lymph node ratios of 0·45-0·65. In logistic regression analysis, number of lymph node metastases (odds ratio (OR) 17·24 for more than 20 metastases, OR 5·28 for 11-20 metastases, OR 2·22 for 6-10 metastases), preoperative basal serum calcitonin (OR 6·24 for over 1000 pg/ml), reoperation (OR 5·34) and extrathyroid extension (OR 2·42) independently predicted failure to reach biochemical cure.

CONCLUSION

Number of lymph node metastases, unlike metastatic lymph node ratio or AJCC node category, determines likelihood of biochemical cure after initial and repeat surgery for node-positive MTC.

Quantitative metastatic lymph node burden and survival in Merkel cell carcinoma

BACKGROUND

Current lymph node (LN) staging for Merkel cell carcinoma (MCC) does not account for the number of metastatic LNs, which is a primary driver of survival in multiple cancers.

OBJECTIVE

To determine the impact of the number of metastatic LNs on survival in MCC.

METHODS

Patients with MCC undergoing surgery were identified from the National Cancer Database (NCDB). The association between metastatic LN number and survival was modeled with restricted cubic splines. A novel nodal classification system was derived by using recursive partitioning analysis. MCC patients undergoing surgery in the Surveillance, Epidemiology, and End Results (SEER) Program were used as validation cohort.

RESULTS

Among 3670 patients in the NCDB, increasing metastatic LN number was associated with decreased survival (P < .001). Mortality risk increased continuously with each additional positive LN when using multivariable, nonlinear modeling. According to a novel staging system derived via recursive partitioning analysis, the hazard ratio for death in multivariable regression compared with patients without LN involvement was 1.24 (P = .049), 2.08 (P < .001), 3.24 (P < .001), and 6.13 (P < .001) for the proposed N1a (1-3 metastatic LNs with microscopic detection), N1b (1-3 metastatic LNs with macroscopic detection), N2 (4-8 metastatic LNs), and N3 (≥9 metastatic LNs), respectively. This system was validated in the SEER cohort and showed improved concordance compared with the American Joint Committee on Cancer, Eighth Edition.

LIMITATIONS

Retrospective design.

CONCLUSIONS

Number of metastatic LNs is the dominant nodal factor driving survival in patients with MCC.

The role of molecular genetics in the clinical management of sporadic medullary thyroid carcinoma: A systematic review

BACKGROUND

The significant variation in the clinical behaviour of sporadic medullary thyroid carcinoma (sMTC) causes uncertainty when planning the management of these patients. Several tumour genetic and epigenetic markers have been described, but their clinical usefulness remains unclear. The aim of this review was to evaluate the evidence for the use of molecular genetic and epigenetic profiles in the risk stratification and management of sMTC.

METHODS

MEDLINE and Embase databases were searched using the MeSH terms "medullary carcinoma", "epigenetics", "molecular genetics", "microRNAs"; and free text terms "medullary carcinoma", "sporadic medullary thyroid cancer", "sMTC", "RET", "RAS" and "miR". Articles containing less than ten subjects, not focussing on sMTC, or not reporting clinical outcomes were excluded. Risk of bias was assessed using a modified version of the Newcastle-Ottawa Scale.

RESULTS

Twenty-three studies met the inclusion criteria, and key findings were summarized in themes according to the genetic and epigenetic markers studied. There is good evidence that somatic RET mutations predict higher rates of lymph node metastasis and persistent disease, and worse survival. There are also several good quality studies demonstrating associations between certain epigenetic markers such as tumour miR-183 and miR-375 expression and higher rates of lymph node and distant metastasis, and worse survival.

CONCLUSIONS

There is a growing body of evidence that tumour genetic and epigenetic profiles can be used to risk stratify patients with sMTC. Further research should focus on the clinical applicability of these findings by investigating the possibility of tailoring management to an individual's tumour mutation profile.

Long-Term Oncologic Outcomes After Curative Resection of Familial Medullary Thyroid Carcinoma

INTRODUCTION

Long-term outcomes after curative resection in patients with germline RET mutations and medullary thyroid cancer (MTC) are highly variable and mutation-specific oncologic outcomes are not well-described.

METHODS

Sixty-six patients identified from 1986 to 2017 from a single-institution cancer database were assessed for recurrence and survival using Kaplan-Meier estimates, and correlated with clinicopathologic features using log-rank or Cox proportional hazards.

RESULTS

Median follow-up was 9.3 years (range 0.3-31.5), median tumor diameter was 1.5 cm (range 0.1-7.5), and preoperative calcitonin was known in 41 patients [median 636 (range 0-9600)]. Overall survival (OS) of the cohort was 94% at 10 years, the cumulative incidence of locoregional recurrence was 38% at 10 years, and 19/24 (79%) patients underwent repeat neck operation. The cumulative incidence of distant recurrence was 27% at 10 years. Predictors of distant recurrence were tumor size, positive lymph nodes, and pre- and postoperative carcinoembryonic antigen, but not calcitonin. M918T mutation-bearing patients had 10-year distant recurrence-free survival of 0%, compared with 83% in all other patients (p < 0.001), and equivalent 10-year OS (100% vs. 92%; p = 0.49).

CONCLUSIONS

Structural and metastatic recurrence is common in patients with germline RET mutations, and MTC and can occur 20 years after initial treatment, however survival remains high. Management should focus on optimal surveillance strategies and long-term control of structural disease.

Risk Factors Associated With Reoperation and Disease-Specific Mortality in Patients With Medullary Thyroid Carcinoma

Importance

The association of initial neck dissection with recurrence in medullary thyroid carcinoma (MTC) has not been evaluated on a population level to date.

Objective

To elucidate risk factors associated with reoperation in MTC and disease-specific mortality.

Design, Setting, and Participants

A retrospective analysis was performed of hospital data obtained from the California Cancer Registry and the Office of Statewide Health Planning and Development from January 1, 1999, through December 31, 2012. The dates of the analysis were January 1, 1999, to December 31, 2012. A population-based sample of 953 patients with MTC was identified. Patients who underwent thyroid surgery and had a minimum postoperative follow-up of 2 years (n = 609) were included in the analysis.

Exposure

Initial neck dissection in MTC.

Main Outcomes and Measures

Recurrent MTC leading to reoperation and disease-specific mortality.

Results

Of the 609 patients with MTC who underwent thyroid surgery, the mean (SD) patient age at diagnosis was 52.6 (17.5) years, and 60.8% (n = 370) of the patients were female. The mean (SD) tumor size was 2.8 (2.0) cm. Although initial central neck dissection is recommended by published MTC guidelines, only 35.5% (216 of 609) of patients underwent central neck dissection at the time of the initial thyroidectomy. The rate of reoperation was 16.3% (99 of 609), and the median time to reoperation was 6.4 months. The presence of lymph node metastasis increased the risk of reoperation (hazard ratio [HR], 3.43; 95% CI, 2.00-5.90), while central and lateral neck dissection performed at the initial operation was protective (HR, 0.53; 95% CI, 0.30-0.93). In patients who underwent reoperation, 45.5% (45 of 99) were disease free at a median follow-up of 7.7 years. Five-year disease-specific mortality for the entire cohort was 13.5% (82 of 609). Independent risk factors for disease-specific mortality included older age (HR, 1.36 per decade; 95% CI, 1.17-1.59), tumor size greater than 2 cm (HR, 2.83; 95% CI, 1.08-7.44 for >2 to 4 cm and HR, 2.89; 95% CI, 1.09-7.71 for >4 cm), and regional (HR, 4.77; 95% CI, 2.29-9.94) and metastatic (HR, 21.08; 95% CI, 9.90-44.89) disease. Reoperation was not associated with increased mortality.

Conclusions and Relevance

Lymph node dissection may decrease recurrence leading to reoperation for patients with MTC. Reoperation is a viable strategy to achieve long-term disease-free survival in appropriately selected patients. Central neck dissection remains underused.

Evaluation of Lymph Node Ratio Association With Long-term Patient Survival After Surgery for Node-Positive Merkel Cell Carcinoma

Importance

Merkel cell carcinoma (MCC) carries the highest mortality rate among cutaneous cancers and is rapidly rising in incidence. Identification of prognostic indicators may help guide patient counseling and treatment planning. Lymph node ratio (LNR), the ratio of positive lymph nodes to the total number of examined lymph nodes, is an established prognostic indicator in other cancers.

Objectives

The primary objective was to evaluate the association between LNR and patient survival after surgery for node-positive MCC. The secondary objective was to evaluate whether the survival rates associated with adjuvant therapies vary by patient LNR status.

Design, Setting, and Participants

Retrospective cohort study of patients with node-positive MCC treated with surgery and lymphadenectomy. We queried the National Cancer Database (NCDB) and the Surveillance, Epidemiology, and End Results (SEER) registry for patient records. Data originated from 2004 through 2017 for the NCDB and from 1973 through 2016 for the SEER registry. The SEER registry comprises a population-based US cohort while cases from the NCDB include all reportable cases from Commission on Cancer-accredited facilities and represents approximately 70% of all newly diagnosed cancers in the United States. All data analysis took place between August 1, 2018, and February 11, 2019.

Exposures

The ratio of positive lymph nodes to the total number of examined lymph nodes, LNR, was stratified into quartiles.

Main Outcomes and Measures

Overall survival (NCDB) and disease-specific survival (SEER).

Results

We identified 736 eligible cases in the NCDB and 538 eligible cases in the SEER registry. Among these 1274 patients, the mean (SD) age was 71.1 (11.5) years, and 401 (31.5%) were women. After controlling for clinical and tumor factors including AJCC N staging, patient LNR of 0.07 to 0.31 (hazard ratio [HR], 1.37; 95% CI, 1.03-1.81) and greater than 0.31 (HR, 2.84; 95% CI, 2.10-3.86) was associated with significantly worse survival than an LNR less than 0.07. Univariate supplementary analysis performed in the SEER data set revealed a similar association of LNR with disease-specific survival. For patients with an LNR greater than 0.31, treatment with surgery and adjuvant chemoradiation therapy was associated with improved survival compared with surgery and adjuvant radiation therapy alone (HR, 0.61; 95% CI, 0.38-0.97), while this was not found for patients with an LNR of 0.31 or lower (HR, 0.93; 95% CI, 0.65-1.33).

Conclusions and Relevance

For lymph node-positive MCC, LNR offers a potentially prognostic metric alongside traditional TNM staging that may be useful for both patient counseling and treatment planning after surgery.

Prognostic value of numbers of metastatic lymph node in medullary thyroid carcinoma: A population-based study using the SEER 18 database

Lymph node (LN) metastases are widely considered as a vital assessment of disease progression, as well as an essential indicator for biochemical cure of medullary thyroid carcinoma (MTC). Prognostic effect of numbers of metastatic LN has not been fully studied and the optimal cut-point of LN numbers has not been established. This population-based study designed to investigate prognostic value of numbers of positive LN and determinate the prognostic factors.Data were generated from Surveillance, Epidemiology, and End Results (SEER) database between 1998 and 2013. X-tile program was applied and cut points for division of LN numbers as low-, medium- and high-risk were 0, 1 to 10, and ≥11. The relationship between numbers of metastatic LN, age, tumor size, extent of tumor, and radiotherapy on overall survival (OS) and disease-specific survival (DSS) were evaluated.A total of 1466 diagnosed primary MTC patients without metastases were eligible for analysis in current study. 945 (64%) patients were classified as no positive LNs, 327 (22%) as 1 to 10 positive LNs, 194 (14%) as ≥11 positive LNs. Patients with older age, tumor size, ≥11 positive LN were associated with unfavorable OS. Those dispensed with radiation had statistically better prognosis than the others. When stratified by age, there was a significant difference in patients ≥45 years within LN categories (log-rank P < .001). When stratified by tumor size, a significant correlation was noted between rising numbers of involved nodes and falling rates of OS in tumor measuring >2cm setting (2-4 cm setting, log-rank P = .003 and >4 cm setting, log-rank P = .014, separately). There was no statistical difference of the area under the curve (AUC) for OS and DSS prediction between LN group and N stage, suggesting the 2 LN systems had the same predictive power for OS and DSS.Numbers of metastatic LN showed prognostic power in survival analysis and remained an independent survival predictor which can be evaluated in MTC treatment decisions for optimum assessment.

Replication of newly proposed TNM staging system for medullary thyroid carcinoma: a nationwide study

A recent study proposed new TNM groupings for better survival discrimination among stage groups for medullary thyroid carcinoma (MTC) and validated these groupings in a population-based cohort in the United States. However, it is unknown how well the groupings perform in populations outside the United States. Consequently, we conducted the first population-based study aiming to evaluate if the recently proposed TNM groupings provide better survival discrimination than the current American Joint Committee on Cancer (AJCC) TNM staging system (seventh and eighth edition) in a nationwide MTC cohort outside the United States. This retrospective cohort study included 191 patients identified from the nationwide Danish MTC cohort between 1997 and 2014. In multivariate analysis, hazard ratios for overall survival under the current AJCC TNM staging system vs the proposed TNM groupings with stage I as reference were 1.32 (95% CI: 0.38-4.57) vs 3.04 (95% CI: 1.38-6.67) for stage II, 2.06 (95% CI: 0.45-9.39) vs 3.59 (95% CI: 1.61-8.03) for stage III and 5.87 (95% CI: 2.02-17.01) vs 59.26 (20.53-171.02) for stage IV. The newly proposed TNM groupings appear to provide better survival discrimination in the nationwide Danish MTC cohort than the current AJCC TNM staging. Adaption of the proposed TNM groupings by the current AJCC TNM staging system may potentially improve accurateness in survival discrimination. However, before such an adaption further population-based studies securing external validity are needed.

EF24 (a Curcumin Analog) and ZSTK474 Emphasize the Effect of Cabozantinib in Medullary Thyroid Cancer

XL184 is a small-molecule kinase inhibitor recently included in first-line systemic therapy for patients with advanced, progressive medullary thyroid cancer (MTC). EF24 is a curcumin analog with a high bioavailability, and ZSTK474 is an inhibitor of the phosphatidylinositol 3-kinase signaling pathway. We investigated the effect of these compounds, alone and in combination, in two rearranged during transfection (RET)-mutated TT and MZ-CRC-1 MTC cell lines and in six mostly RET wild-type human MTC primary cultures. Low IC50 values demonstrated the efficacy of the drugs, whereas the combination index revealed an important synergistic effect of combinations of XL184 + ZSTK474 and XL184 + EF24. Cell-cycle changes and the induction of apoptosis or necrosis were modulated by single compounds or combinations thereof. Both XL184 and EF24, alone or combined, were effective in reducing calcitonin secretion. Western blot and in-cell Western analysis showed that the compounds prompted a decrease in general reactivity to phosphorylated antibodies. Our data confirm XL184 alone as the reference drug for RET-mutated MTC, but we also demonstrated that EF24 alone is effective in inhibiting MTC cell viability. We tested the combinations XL184 + ZSTK474 and XL184 + EF24 too, finding that they act synergistically, irrespective of RET mutation status.

Analysis of risk factors for cervical lymph node metastases in patients with sporadic medullary thyroid carcinoma

Objective

Medullary thyroid carcinoma (MTC) is classified as either sporadic or inherited. This study was performed to analyze the risk factors for cervical lymph node metastases and predict the indication for prophylactic lateral neck dissection in patients with sporadic MTC.

Methods

Sixty-five patients with sporadic MTC were retrospectively reviewed. Univariate analysis with the chi-square test and multiple logistic regression analysis were applied to identify the clinicopathological features (sex, age, tumor size, number of tumor foci, capsule or vascular invasion, and others) associated with cervical lymph node metastases.

Results

The metastasis rates in the central and lateral compartments were 46.2% (30/65) and 40.0% (26/65), respectively. The incidence of cervical lymph node metastases was significantly higher in patients with a tumor size of >1 cm, tumor multifocality, and thyroid capsule invasion. Only thyroid capsule invasion was an independent predictive factor for central compartment metastases and lateral neck metastases. The possibility of central compartment metastases was significantly higher when the preoperative serum carcinoembryonic antigen concentration was >30 ng/mL (60.0% vs. 34.3%).

Conclusions

MTC is associated with a high incidence of cervical lymph node metastases. Prophylactic lateral node dissection is necessary in patients with thyroid capsule invasion or a high serum carcinoembryonic antigen concentration.

Survival in patients with medullary thyroid cancer after less than the recommended initial operation

BACKGROUND AND OBJECTIVES

We aimed to evaluate the disease specific-survival (DSS) of patients with Medullary Thyroid Cancer (MTC) confined to the central neck based on the extent of the initial operation.

METHODS

This retrospective review of patients with MTC from the SEER registry from 2004 to 2012 excluded patients with lateral neck involvement or distant metastases.

RESULTS

The cohort (n = 766) included 85(11%) less than total thyroidectomies (TT), 212(28%) TT alone, and 469(61%) TT with lymph node excision. Mean tumor size was similar (2.2cm for <TT, 1.9 for TT alone, and 2.2 for TT with nodes, p=0.13). Patients receiving a TT with nodal excision were more likely to have multifocal tumors (8% <TT, 22% TT alone, and 27% TT with nodes, P < 0.001), and extrathyroidal extension (1% <TT, 4% TT alone, and 9% TT with nodes, P = 0.005). Even after controlling for significant predictors of DSS, extent of the initial operation did not predict survival (HR 0.28 for <TT, 95% CI 0.26-3.11 and HR 0.62 for TT alone, 95% CI 0.17-2.22 compared to TT with nodes, P = NS for all).

CONCLUSION

According to population-based SEER registry data, the extent of initial resection may not significantly change DSS in patients with MTC confined to the central neck.

Medullary Thyroid Carcinoma in MEN2A: ATA Moderate- or High-Risk RET Mutations Do Not Predict Disease Aggressiveness

CONTEXT

High-risk RET mutations (codon 634) are associated with earlier development of medullary thyroid carcinoma (MTC) and presumed increased aggressiveness compared with moderate-risk RET mutations.

OBJECTIVE

To determine whether high-risk RET mutations are more aggressive.

DESIGN

Retrospective cohort study using institutional multiple endocrine neoplasia type 2 registry.

SETTING

Tertiary cancer care center.

PATIENTS

Patients with MTC and moderate- or high-risk germline RET mutation.

INTERVENTION

None (observational study).

MAIN OUTCOME MEASURES

Proxies for aggressiveness were overall survival (OS) and time to distant metastatic disease (DMD).

RESULTS

A total of 127 moderate-risk and 135 high-risk patients were included (n = 262). Median age at diagnosis was 42.3 years (range, 6.4 to 86.4 years; mean, 41.6 years) for moderate-risk mutations and 23.0 years (range, 3.7 to 66.8 years; mean, 25.6 years) for high-risk mutations (P < 0.0001). Moderate-risk patients had more T3/T4 tumors at diagnosis (P = 0.03), but there was no significant difference for N or M stage and no significant difference in OS (P = 0.40). From multivariable analysis for OS, increasing age [hazard ratio (HR), 1.05/y; 95% confidence interval (CI), 1.03 to 1.08], T3/T4 tumor (HR, 2.73; 95% CI, 1.22 to 6.11), and M1 status at diagnosis (HR, 3.93; 95% CI, 1.61 to 9.59) were significantly associated with worse OS but high-risk mutation was not (P = 0.40). No significant difference was observed for development of DMD (P = 0.33). From multivariable analysis for DMD, only N1 status at diagnosis was significant (HR, 2.10; 95% CI, 1.03 to 4.27).

CONCLUSIONS

Patients with high- and moderate-risk RET mutations had similar OS and development of DMD after MTC diagnosis and therefore similarly aggressive clinical courses. High-risk connotes increased disease aggressiveness; thus, future guidelines should consider RET mutation classification by disease onset (early vs late) rather than by risk (high vs moderate).

Chemotherapy and tyrosine-kinase inhibitors for medullary thyroid cancer

Medullary thyroid cancer (MTC) represents 3% of all clinical thyroid cancers and arises from thyroid C cells that produce calcitonin. Locally advanced or metastatic MTC requires a careful work-up including measurement of serum calcitonin and carcinoembryonic antigen, determination of their doubling time and comprehensive imaging to determine the extent of the disease, its aggressiveness, and the need for treatment. Cytotoxic chemotherapy can control tumor burden in some patients with response rates of around 20% in old series. For the last 10 years, systemic therapy for MTC patients with large tumor burden and documented progression of the disease has involved the use of tyrosine kinase inhibitors targeting VEGFR and ret. Progression-free survival benefits have been demonstrated for both vandetanib and cabozantinib, as compared to placebo. Although these molecules are effective, they also have specific toxicity profiles which require a thorough clinical management in specialized centers. In the present review, we describe the work-up and treatment modalities of patients with advanced or metastatic medullary thyroid cancer with a focus on chemotherapy and targeted therapy results.

Trends in the presentation, treatment, and survival of patients with medullary thyroid cancer over the past 30 years

BACKGROUND

The impact of recent medical advances on disease presentation, extent of operation, and disease-specific survival for patients with medullary thyroid cancer is unclear.

METHODS

We used the Surveillance, Epidemiology, and End Results registry to compare trends over 3 time periods, 1983-1992, 1993-2002, and 2003-2012.

RESULTS

There were 2,940 patients diagnosed with medullary thyroid cancer between 1983 and 2012. The incidence of medullary thyroid cancer increased during this time period from 0.14 to 0.21 per 100,000 population, and mean age at diagnosis increased from 49.8 to 53.8 (P < .001). The proportion of tumors ≤1 cm also increased from 11.4% in 1983-1992, 19.6% in 1993-2002, to 25.1% in 2003-2012 (P < .001), but stage at diagnosis remained constant (P = .57). In addition, the proportion of patients undergoing a total thyroidectomy and lymph node dissection increased from 58.2% to 76.5% during the study period (P < .001). In the most recent time interval, 5-year, disease-specific survival improved from 86% to 89% in all patients (P < .001) but especially for patients with regional (82% to 91%, P = .003) and distant (40% to 51%, P = .02) disease.

CONCLUSION

These data demonstrate that the extent of operation is increasing for patients with medullary thyroid cancer. Disease-specific survival is also improving, primarily in patients with regional and distant disease.

Role of CDKN2C Copy Number in Sporadic Medullary Thyroid Carcinoma

BACKGROUND

The cyclin-dependent-kinase inhibitors (CDKN)/retinoblastoma (RB1) pathway has been implicated as having a role in medullary thyroid carcinoma (MTC) tumorigenesis. CDKN2C loss has been associated with RET-mediated MTC in humans but with minimal phenotypic correlation provided. The objective of this study was to evaluate the association between tumor RET mutation status, CDKN2C loss, and aggressiveness of MTC in a cohort of patients with sporadic disease.

METHODS

Tumors from patients with sporadic MTC treated at a single institution were evaluated for somatic RET^M918T mutation and CDKN2C copy number loss. These variables were compared to patient demographics, pathology detail, clinical course, and disease-specific and overall survival.

RESULTS

Sixty-two MTC cases with an initial surgery date ranging from 1983 to 2009 met the inclusion criteria, of whom 36 (58%) were male. The median age at initial surgery was 53 years (range 22-81 years). The median tumor size was 30 mm (range 6-145 mm) with 29 (57%) possessing extrathyroidal extension. Nodal and/or distant metastasis at presentation was found in 47/60 (78%) and 12/61 (20%) patients, respectively. Median follow-up time was 10.5 years (range 1.1-27.8 years) for the censored observations. The presence of CDKN2C loss was associated with worse M stage and overall AJCC stage. Median overall survival of patients with versus without CDKN2C loss was 4.14 [confidence interval (CI) 1.93-NA] versus 18.27 [CI 17.24-NA] years (p < 0.0001). Median overall survival of patients with a combined somatic RET^M918T mutation and CDKN2C loss versus no somatic RET^M918T mutation and CDKN2C loss versus somatic RET^M918T mutation and CDKN2C 2N versus no somatic RET^M918T mutation and CDKN2C 2N was 2.38 [CI 1.67-NA] years versus 10.81 [CI 2.46-NA] versus 17.24 [CI 9.82-NA] versus not reached [CI 13.46-NA] years (p < 0.0001).

CONCLUSIONS

The detection of somatic CDKN2C loss is associated with the presence of distant metastasis at presentation as well decreased overall survival, a relationship enhanced by concomitant RET^M918T mutation. Further defining the genes involved in the progression of metastatic MTC will be an important step toward identifying pathways of disease progression and new therapeutic targets.