Pathological characteristics of low-risk papillary thyroid microcarcinoma with progression during active surveillance

Which Ultrasound Characteristics Predict Lymphatic Spread of Papillary Thyroid Cancer?

INTRODUCTION

The 2015 American Thyroid Association guidelines recommend lymph node mapping US in patients with definitive cytological evidence of thyroid cancer. Suspicious lymph node features on imaging including enlarged size (>1 cm in any dimension), architectural distortion, loss of fatty hilum, and microcalcifications often prompt evaluation with fine needle aspiration. There is no universally agreed upon model for determining which ultrasound characteristics most strongly correlate with metastatic disease.

METHODS

A retrospective review of patients with confirmed papillary thyroid cancer (PTC) undergoing lymph node mapping ultrasound from 2013 to 2019 was performed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value were calculated for each individual ultrasound characteristic as well as for characteristic combinations.

RESULTS

Data from 119 lymph nodes were included. Malignant lymph nodes were more likely to be enlarged (71% versus 61%, P < 0.001) and to have each individual suspicious feature. Loss of fatty hilum had the highest sensitivity (89%) but was not specific (19%) for metastatic disease. Architectural distortion was found to have the highest specificity (87%). A combination of the four features was found to have higher specificity (97%) and PPV (88%) than any individual feature or combination of two/three features.

CONCLUSIONS

A combination of four sonographic features correlates with metastatic PTC to lymph nodes and has the highest specificity and PPV for malignancy. A risk stratification model based on these features may lead to better classification of ultrasound findings in PTC patients with concern for nodal metastases.

Survival benefits of extensive surgery in patients with papillary thyroid microcarcinoma

BACKGROUND

Despite the guidelines recommending thyroid lobectomy, many papillary thyroid microcarcinoma (PTMC) patients still undergo total thyroidectomy. PTMC's optimal treatment remains unclear. We aimed to determine whether total thyroidectomy improves outcomes compared to less extensive surgery.

METHODS

We analyzed 6064 PTMC adult patients from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2019) who underwent either total thyroidectomy (n ​= ​3652) or less extensive surgery (n ​= ​2412). Endpoints were overall survival, cancer-specific survival, and recurrence.

RESULTS

Total thyroidectomy patients had a 5.2 ​% mortality rate versus 8.1 ​% with less extensive surgery. Recurrence occurred in 1 (0.03 ​%) total thyroidectomy patient compared to 24 (1.0 ​%) less extensive surgery patients (HR 0.07, p ​= ​0.01). Median survival was 8.1 years for total thyroidectomy versus 8.8 years for less extensive surgery. Overall survival favored total thyroidectomy (p ​= ​0.001) but cancer-specific survival did not differ.

CONCLUSION

Although total thyroidectomy may not improve cancer-specific survival, it lowers recurrence risk and confers an overall survival advantage for PTMC patients. These findings may help guide surgical decisions.

Survival outcomes of low-risk papillary thyroid carcinoma at different risk levels: a corollary for active surveillance

Background

This study aims to compare the outcomes of active surveillance (AS) in low-risk papillary thyroid carcinoma (PTC) patients with different tumor sizes and lymph node metastasis status, in order to establish appropriate management strategies. By analyzing these results, this study provides valuable insights for the effective management of such patients, addressing the issues and challenges associated with AS in practical clinical practice.

Methods

The study utilized the SEER database supported by the National Cancer Institute of the United States, extracting data of PTC diagnosed between 2000 and 2015. Statistical analyses were conducted using inverse probability weighting (IPTW) and propensity score matching (PSM), including Kaplan-Meier survival curves and Cox regression models, to evaluate the impact of different tumor sizes and lymph node metastasis status on thyroid cancer-specific survival (TCSS).

Results

A total of 57,000 PTC patients were included, with most covariates having standardized mean differences below 10% after IPTW and PSM adjustments. The TCSS of PTC with a diameter smaller than 13mm is significantly better than that of tumors with a diameter larger than 13mm, regardless of the presence of lymph node metastasis. Among PTC cases with a diameter smaller than 13mm, the TCSS of patients is similar, regardless of the presence of lymph node metastasis. However, in PTC cases with a diameter larger than 13mm, the presence of lateral neck lymph node metastasis (N1b stage) significantly impacts the TCSS, although the absolute impact on TCSS rate is minimal.

Conclusion

The treatment strategy of AS is safe for patients with T1a stage papillary thyroid microcarcinoma (PTMC). However, for patients with T1b stage, if the tumor diameter exceeds 13mm or there is lymph node metastasis in the lateral neck region, the TCSS will be significantly affected. Nevertheless, the absolute impact on survival is relatively small.

An Ultrasound-based Prediction Model for Occult Contralateral Papillary Thyroid Carcinoma in Adolescents and Young Adults

RATIONALE AND OBJECTIVES

To investigate the occult contralateral papillary thyroid carcinoma (PTC)-associated ultrasound (US) and clinical characteristics and establish a US-based model for the prediction of occult contralateral carcinoma in adolescents and young adults (AYAs) who were diagnosed with unilateral thyroid carcinoma preoperatively.

MATERIALS AND METHODS

From January 2015 to December 2020, patients who were diagnosed with unilateral thyroid carcinoma by preoperative US examination and underwent total thyroidectomy or thyroid lobectomy with more than 60 months of US follow-up at our hospital were retrospectively collected. Univariate and multivariate analyses were applied to identify the independent risk factors associated with occult contralateral PTC in AYAs, on which a prediction model was developed. The performance of the model was evaluated with accuracy, sensitivity, specificity, and the area under the receiver operating characteristic curve.

RESULTS

Occult contralateral PTC was found in 91 of 365 (24.9%) PTC patients with a median age at diagnosis of 26 years (interquartile range, 24-29 years). The multivariate analysis indicated that the presence of contralateral benign nodule, intra-tumoral calcification, and intraglandular dissemination were significantly associated with occult contralateral PTC in AYAs. The prediction model, which incorporated all independent predictors, yielded an area under the receiver operating characteristic curve of .661 (95% CI: .602-.719). The accuracy, sensitivity and specificity were 67.9%, 54.9%, and 72.3%, respectively.

CONCLUSION

The US-based prediction model proposed here exhibited a favorable performance for predicting occult contralateral PTC, which might be used to determine the appropriate extent of surgery for AYAs who had a preoperative diagnosis of unilateral thyroid carcinoma.

Frequency of TERT Promoter Mutations in Real-World Analysis of 2,092 Thyroid Carcinoma Patients

BACKGRUOUND

Telomerase reverse transcriptase (TERT) promoter mutations are associated with increased recurrence and mortality in patients with thyroid carcinoma. Previous studies on TERT promoter mutations were retrospectively conducted on a limited number of patients.

METHODS

We prospectively collected data on all consecutive patients who underwent thyroid carcinoma surgery between January 2019 and December 2020 at the Samsung Medical Center, Seoul, Korea. We included 2,092 patients with thyroid carcinoma.

RESULTS

Of 2,092 patients, 72 patients (3.4%) had TERT promoter mutations. However, the frequency of TERT promoter mutations was 0.5% in papillary thyroid microcarcinoma (PTMC) ≤1 cm and it was 5.8% in papillary thyroid carcinoma (PTC) >1 cm. The frequency of TERT promoter mutations was significantly associated with older age at diagnosis (odds ratio [OR], 1.12; P<0.001), larger primary tumor size (OR, 2.02; P<0.001), and aggressive histological type (OR, 7.78 in follicular thyroid carcinoma; OR, 10.33 in poorly differentiated thyroid carcinoma; OR, 45.92 in anaplastic thyroid carcinoma; P<0.001). Advanced T stage, advanced N stage, and distant metastasis at diagnosis were highly prevalent in mutated thyroid cancers. However, initial distant metastasis was not present in patients with TERT promoter mutations in PTMC. Although the C228T mutation was more highly detected than the C250T mutation (64 cases vs. 7 cases), there were no significant clinicopathological differences.

CONCLUSION

This study is the first attempt to investigate the frequency of TERT promoter mutations in a real-world setting. The frequency of TERT promoter mutations in PTC was lower than expected, and in PTMC, young patients, and female patients, the frequency was very low.

The BRAFV600E Mutation Is Not a Risk Factor for More Aggressive Tumor Behavior in Radiogenic and Sporadic Papillary Thyroid Carcinoma at a Young Age

Simple Summary

Analysis of the groups of young Ukrainian patients (aged ≤28 years) with radiogenic and sporadic papillary thyroid carcinomas (PTCs) showed that the frequency of BRAF^V600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAF^V600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAF^V600E-negative tumors. Comparison of the BRAF^V600E-positive PTCs across the groups found a virtual absence of differences, while the BRAF^V600E-negative tumors differed markedly and displayed a higher frequency of invasive tumor features in the radiogenic PTCs. Hence, there is evidence that BRAF^V600E does not confer a more aggressive course of PTC in young patients regardless of tumor etiology.

Abstract

Histopathological changes in the fusion oncogene-driven papillary thyroid carcinomas (PTCs) from children and adolescents exposed to Chernobyl fallout have been extensively studied. However, characteristics of the radiogenic BRAF^V600E-positive PTCs, whose proportion is growing with time, are not well described yet. We analyzed the relationship between the BRAF^V600E status (determined immunohistochemically with the VE1 antibody) and the clinicopathological features of 247 radiogenic and 138 sporadic PTCs from young Ukrainian patients aged ≤28 years. The frequency of BRAF^V600E was increasing with patient age, consistently remaining lower in radiogenic PTCs. In both etiopathogenic groups, the BRAF^V600E-positive PTCs more frequently had a dominant papillary growth pattern, smaller tumor size, higher Ki67 labeling index, and a frequency of the major indicators of tumor invasiveness that is lower than or equal to that of the BRAF^V600E-negative tumors. Comparison of the BRAF^V600E-positive PTCs across the groups found a virtual absence of differences. In contrast, the BRAF^V600E-negative radiogenic PTCs displayed less frequent dominant papillary and more frequent solid growth patterns, lower Ki67 labeling index, and higher invasiveness than the BRAF^V600E-negative sporadic tumors. Thus, BRAF^V600E is not associated with a more aggressive course of PTC in young patients regardless of etiology. The major clinicopathological differences between the radiogenic and sporadic PTCs are observed among the BRAF^V600E-negative tumors.

Position paper from the Japan Thyroid Association task force on the management of low-risk papillary thyroid microcarcinoma (T1aN0M0) in adults

The incidence of thyroid carcinoma has been increasing worldwide. This is interpreted as an increase in the incidental detection of papillary thyroid microcarcinomas (PTMCs). However, mortality has not changed, suggesting overdiagnosis and overtreatment. Prospective clinical trials of active surveillance for low-risk PTMC (T1aN0M0) have been conducted in two Japanese institutions since the 1990s. Based on the favorable outcomes of these trials, active surveillance has been gradually adopted worldwide. A task force on the management of PTMC in adults organized by the Japan Thyroid Association therefore conducted a systematic review and has produced the present position paper based on the scientific evidence concerning active surveillance. This paper indicates evidence for the increased incidence of PTMC, favorable surgical outcomes for low-risk PTMC, recommended criteria for diagnosis using fine needle aspiration cytology, and evaluation of lymph node metastasis (LNM), extrathyroidal extension (ETE) and distant metastasis. Active surveillance has also been reported with a low incidence of disease progression and no subsequent recurrence or adverse events on survival if conversion surgery was performed at a slightly advanced stage. Active surveillance is a safe and valid strategy for PTMC, because it might preserve physical quality of life and reduce 10-year medical costs. However, some points should be noted when performing active surveillance. Immediate surgery is needed for PTMC showing high-risk features, such as clinical LNM, ETE or distant metastasis. Active surveillance should be performed under an appropriate medical team and should be continued for life.

Thyroid Parenchyma Microcalcifications on Ultrasound for Predicting Lymph Node Metastasis in Papillary Thyroid Carcinoma: A Prospective Multicenter Study in China

Objective: Cervical lymph node metastasis (LNM) was found to be clinically significant prognostic factors of patients with papillary thyroid carcinomas (PTC). Ultrasound (US) characteristics of thyroid nodules and thyroid parenchyma may be used to predict LNM. To investigate the value of nodular US features as well as thyroid parenchymal microcalcifications on US in predicting LNM in patients with PTC. Methods: This prospective study was approved by the Institutional Review Board. From January 2018 to June 2019, 971 consecutive patients with solitary PTC who underwent preoperative neck US evaluation were included from six hospitals in China. The US features of thyroid nodules as well as thyroid parenchyma microcalcifications were carefully evaluated based on the static images and dynamic clips. Univariate and multivariate analyses were performed to determine independent predictors of LNM. Results: Of the 971 patients, 760 were female, 211 were male. According to the pathological examination, 241(24.82%) patients were found with cervical LNM (LNM positive group), while 730 (75.18%) patients were not (LNM negative group). Multiple logistic regression analysis showed that young age (<55 years old) (OR = 1.522, P = 0.047), large size (>10 mm) (OR = 1.814, P < 0.001), intratumoral microcalcifications (OR = 1.782, P = 0.002) and thyroid parenchyma microcalcifications (OR = 1.635, P = 0.046) were independent risk factors for LNM of PTC. Conclusions: Young age, large nodule size, intratumoral microcalcifications, as well as thyroid parenchyma microcalcifications on US are independent predictors of cervical LNM for patients with PTC.

Choosing Optimal Microcarcinoma Patients for Active Surveillance Study (Compass): Effectiveness Evaluation of a Preoperative Clinical Framework

OBJECTIVE

Active surveillance (AS) is a management alternative for patients with low-risk papillary thyroid microcarcinoma (PTMC). To decide the best candidates for AS, clinicians can use a framework to classify PTMC patients as ideal, appropriate, or inappropriate. This study aimed to explore the correlation between the framework categories and surgical pathology.

METHODS

This multicenter retrospective study was conducted between 2014 and 2016. We included 1997 patients who underwent thyroid surgery for the first time due to suspected PTMC and were confirmed as PTMC by postoperative pathology. The consistency of modified preoperative risk stratification and the pathologic condition were evaluated using a consistency ratio and the Kappa coefficient. Stratified analysis was also performed to test consistency in different age groups.

RESULTS

Based on the decision-making framework, 558 (27.9%) patients could receive AS while 810 (40.6%) patients did not require immediate surgery according to the actual postoperative pathology. The sensitivity, false-positive rate, specificity, false-negative rate, and consistency rate were 82.39%, 56.91%, 43.09%, 17.61%, and 66.45%, respectively. The Kappa value was 0.268. Stratified analysis showed that the sensitivity was 87.7% among patients aged 18 to 59 years. In the group aged ≥60 years, the specificity was up to 87.5%, but the sensitivity was low.

CONCLUSION

The results of the modified risk-stratified clinical decision-making framework did not have a high consistency with the postoperative results. However, the framework showed a good effect in selecting patients for immediate surgery in the younger group and patients for AS in the older group.

Marked Decrease Over Time in Conversion Surgery After Active Surveillance of Low-Risk Papillary Thyroid Microcarcinoma

Background: Active surveillance for low-risk papillary microcarcinoma (PMC) of the thyroid is an accepted and safe management strategy. However, some patients undergo conversion surgery after the initiation of active surveillance for various reasons. We investigated the reasons for conversion surgery and whether and how they changed over time. Methods: We enrolled 2288 patients with PMC who underwent active surveillance. Of these, 162 (7.1%) underwent conversion surgery >12 months after initiating active surveillance due to disease progression (57 patients), patient preference (43 patients), physician preference (31 patients), other associated thyroid or parathyroid diseases (24 patients), and other reasons (7 patients). We analyzed cumulative conversion rates not only in the whole cohort but also in the first three major subsets based on the reasons for surgery. We also divided our whole cohort into two groups based on the period of active surveillance commencement: the first-half group (February 2005-November 2011; 561 patients) and the second-half group (December 2011-June 2017; 1727 patients). Results: The criteria for PMC progression did not differ between the first- and second-half groups. The proportion of female patients in the physician preference group was significantly higher than that in the disease progression and the patient preference groups. Tumor size at surgery was larger, and tumor volume-doubling rate was higher in the disease progression group than in the other two groups. Patients in the second-half group were significantly less likely to undergo conversion surgery than those in the first-half group. Furthermore, conversion surgery rates in the second-half group were significantly lower than those in the first-half group in the patient preference, physician preference, and disease progression groups. Conclusions: Patients with PMC in the second-half group were significantly less likely to undergo conversion surgery than those in the first-half group regardless of the reason. This is probably because data accumulation of favorable outcomes with active surveillance significantly contributed to physicians' confidence and patients' trust and understanding of this disease.

Indications and Strategy for Active Surveillance of Adult Low-Risk Papillary Thyroid Microcarcinoma: Consensus Statements from the Japan Association of Endocrine Surgery Task Force on Management for Papillary Thyroid Microcarcinoma

Background: The question of how to manage patients with low-risk papillary thyroid microcarcinoma (PTMC; T1aN0M0) has recently become an important clinical issue. Two Japanese centers have conducted prospective clinical trials of active surveillance (AS) for low-risk PTMC since the 1990s, reporting favorable outcomes. This policy has thus seen gradual adoption worldwide to avoid overtreatment. Not all PTMCs are suitable for AS, however, and many physicians still hesitate to apply the management policy in daily clinical practice. A task force on management for PTMC created by the Japan Association of Endocrine Surgery collected and analyzed bibliographic evidence and has produced the present consensus statements regarding indications and concrete strategies for AS to facilitate the management of adult patients diagnosed with low-risk PTMC. Summary: These statements provide indications for AS in adult patients with T1aN0M0 low-risk PTMC. PTMCs with clinical lymph node metastasis, distant metastasis, recurrent laryngeal nerve (RLN) paralysis due to carcinoma invasion, or protrusion into the tracheal lumen warrant immediate surgery. Tumors suspected of aggressive subtypes on cytology are recommended for immediate surgery. Immediate surgery is also recommended for tumors adherent to the trachea or located along the course of the RLN. Practical strategies include diagnosis, decision-making, follow-up, and monitoring related to the implementation of AS. The rate of low-risk PTMC progression is lower in older patients. However, we recommend continuing AS as long as circumstances permit. Future tasks in optimizing management for low-risk PTMC are also described, including molecular markers and patient-reported outcomes. Conclusions: An appropriate multidisciplinary team is necessary to accurately evaluate primary tumors and lymph nodes at the beginning of and during AS, and to adequately reach a shared-decision with individual patients. If appropriately applied, AS of low-risk PTMC is a safe management strategy offering favorable outcomes and preserves quality of life at low cost.

Pros and cons of hemi-thyroidectomy for low-risk differentiated thyroid cancer

The debate regarding the surgical management of low-risk differentiated thyroid cancer (DTC) is ongoing. The recommended extent of surgery in DTC is based on an assessment of the predicted risk of recurrence and recent guidelines reflect an evolving philosophy of de-escalation of surgical management, informed by a growing understanding of the determinants of tumour biology and important prognostic factors. However, our current clinical and pathological risk stratification processes are imperfect and hence there is significant variation in clinical practice. Surgeons face the challenge of finding the balance between avoiding overtreatment, minimizing complications and providing adequate oncological management. This article discusses the nuances of the current management guidelines as well as the important considerations in preoperative decision making.

Thyroid Papillary Microtumor: Validation of the (Updated) Porto Proposal Assessing Sex Hormone Receptor Expression and Mutational BRAF Gene Status

Given the high incidence and excellent prognosis of many papillary thyroid microcarcinomas, the Porto proposal uses the designation papillary microtumor (PMT) for papillary microcarcinomas (PMCs) without risk factors to minimize overtreatment and patients' stress. To validate Porto proposal criteria, we examined a series of 190 PMC series, also studying sex hormone receptors and BRAF mutation. Our updated Porto proposal (uPp) reclassifies as PMT incidental PMCs found at thyroidectomy lacking the following criteria: (a) detected under the age of 19 years; (b) with multiple tumors measuring >1 cm adding up all diameters; and (c) with aggressive morphologic features (extrathyroidal extension, angioinvasion, tall, and/or hobnail cells). PMCs not fulfilling uPp criteria were considered "true" PMCs. A total of 102 PMCs were subclassified as PMT, 88 as PMC, with no age or sex differences between subgroups. Total thyroidectomy and iodine-131 therapy were significantly more common in PMC. After a median follow-up of 9.6 years, lymph node metastases, distant metastases, and mortality were only found in the PMC subgroup. No subgroup differences were found in calcifications or desmoplasia. Expression of estrogen receptor-α and estrogen receptor-β, progesterone receptor, and androgen receptor was higher in PMC than in nontumorous thyroid tissue. BRAF mutations were detected in 44.7% of PMC, with no differences between subgroups. In surgical specimens, the uPp is a safe pathology tool to identify those PMC with extremely low malignant potential. This terminology could reduce psychological stress associated with cancer diagnosis, avoid overtreatment, and be incorporated into daily pathologic practice.

Active surveillance for low-risk small papillary thyroid cancer in North American countries: past, present and future (bridging the gap between North American and Asian practices)

Papillary thyroid cancer (PTC) is increasingly being diagnosed worldwide; yet the mortality remains very low, suggesting widespread overdiagnosis. While traditional management of PTC includes thyroid surgery, sometimes followed by radioactive iodine treatment, there is a global trend towards more conservative approaches for patients who are considered as the lowest risk of recurrence or death from their disease. Active surveillance (AS), once called watchful waiting, involves close follow-up, with the intention to intervene if the cancer progresses, or on patient request. The Kuma Hospital in Japan was the first to introduce AS as an alternative to immediate thyroid surgery for low-risk papillary thyroid microcarcinomas (PTMC, <1 cm) in 1993. Accumulated evidence over the years has shown that AS is a safe and effective approach in select patients, with a low rate of cancer progression during AS. Consequently, the Japanese Clinical Guidelines for treatment of thyroid tumor approved AS as a first-line management for patients with asymptomatic PTMC in 2010. Subsequently, the latest 2015 American Thyroid Association guidelines endorsed AS as an alternative approach to immediate surgery for cytologically confirmed very low-risk PTC. However, the acceptance, feasibility and results of AS in patients with low-risk PTC outside of Japan are still largely unknown. Most guidelines recommend that thyroid nodules <1 cm should not be aspirated but instead monitored regardless of the ultrasonographic characteristics. In essence, these patients are also being subjected to AS. Specific recommendations and the role of molecular testing for the optimal selection of PTMC patients for an AS management approach are not well established. Furthermore, research is needed to assess the long-term clinical and psychosocial outcomes in patients with larger tumor sizes (>1 cm) who undergo screening and diagnosis according to the North American guidelines and practices. The first Canadian prospective observational study launched in 2016 is intended to complement the existing data for AS of small low-risk PTC (≤2 cm) and may provide insight into the different approaches in North American and Asian practices. This review intends to summarize the development and the rationale of AS for PTMC and highlights significant differences between North American and Japanese practices.

Ki67 in endocrine neoplasms: to count or not to count, this is the question! A systematic review from the English language literature

BACKGROUND

Endocrine neoplasms are generally slow-growing tumors that can show hormonal activity and give metastases. In most cases they are benign and clearly malignant forms are easy to diagnose. However, borderline forms may occur and be, for the pathologists, very difficult to classify. In these cases, there is a strong need to identify factors that may aid. Official classification systems for endocrine neoplasms are based on the evaluation of proliferation and, in most cases, they rely on mitotic count. In support, the study of Ki67 is carried out which, however, has not yet been included in any official classification system, except for neuroendocrine neoplasms of the gastro-entero-pancreatic tract.

PURPOSE

The aim of the present study was to investigate the proven or unproven role of Ki67 in endocrine neoplasms, in different districts, in order to bring to light the substantial differences, in terms of proliferation, existing between neoplasms so similar, but at the same time, so different.

METHODS

A thorough search of English language literature was performed, looking for articles concerning Ki67 in five endocrine neoplasms (pituitary adenomas, thyroid neoplasms, adrenocortical neoplasms, pheochromocytomas and paragangliomas).

RESULTS

From 2170, 236 articles were selected and it was seen that the endocrine neoplasm in which Ki67 was most studied was the pituitary, where it still shows a controversial role. In other neoplasms different roles were identified.

CONCLUSION

The pathologist should be aware of the contribution that this proliferative marker can give to the diagnosis and, sometimes, to the therapy selection, for the clinician.

Active surveillance of low-risk papillary thyroid microcarcinomas

In 1993, active surveillance of low-risk papillary thyroid microcarcinomas (PTMCs) started in Kuma Hospital, Kobe, Japan. It has spread globally after the publishing of American Thyroid Association (ATA) guidelines. During our hospital's active surveillance program, few patients (8.0%) showed tumor size enlargement ≥3 mm or the new appearance of node metastasis (3.8%) at 10-year follow-up. Conversion surgery was recommended for patients with disease progression. To date, no patients showed significant recurrence or metastasis or died with thyroid carcinoma when patients underwent active surveillance or after surgery due to PTMC progression. Unlike clinical papillary thyroid carcinoma (PTC), elderly patients' PTMCs were less progressive compared to those of young and middle-aged patients, indicating that elderly patients are strong candidates for the active surveillance of their PTMC. Although young patients' PTMCs are the most progressive, >50% and >75% of patients in their 20s and 30s would avoid conversion surgical treatment in their lifetime, respectively (according to estimated lifetime probability), indicating that such young patients are still candidates for active surveillance. It can thus be concluded that active surveillance is appropriate to be first management for PTMCs, based on the accumulation of favorable outcomes of PTMC patients who have undergone active surveillance, as well as the lower incidences of unfavorable events and lower medical cost than immediate surgery.

Active surveillance as a management strategy for papillary thyroid microcarcinoma

Active surveillance (AS) can be considered as a treatment strategy for low risk papillary thyroid microcarcinoma (PTMC), with the absence of clinically apparent lymph nodes, extrathyroidal extensions, and distant metastasis. After reviewing the reports on AS of low risk PTMCs worldwide, we introduced AS, and discussed the selection criteria for active surveillance candidates based on different guidelines and the follow-up schedules. Moreover, the requirement of cytological diagnosis, progression evaluation methods, necessity of thyrotropin suppression, and medical costs were issues that both clinicians and patients considered. The usefulness of AS for low risk PTMC patients depended on accurate and confidential evaluation of patient risk. Clinicians may adopt measures like dynamic monitoring, risk stratification, and making personal follow-up schedules to minimize these potential risks. By appropriately selecting PTMC patients, AS can be an effective alternative treatment to immediate surgery.

Active surveillance of low-risk papillary thyroid microcarcinomas in Japan and other countries: a review

Introduction: Active surveillance of low-risk papillary thyroid microcarcinomas (PTMCs) was initiated in Japan in 1993 and has since been adopted in many countries, especially after its approval by the American Thyroid Association in 2015.Areas covered: We performed a literature review in Medline/PubMed to identify studies that used active surveillance for PTMCs. Moreover, we performed a literature review about the increased incidence of thyroid microcarcinomas in relation to the relative stability of deaths due to thyroid carcinomas.Expert opinion: No patients showed life-threatening metastasis/recurrence or died of thyroid carcinoma during active surveillance or after conversion surgery following PTMC progression. Thus, active surveillance should be the first-line management of PTMCs without high-risk features. In the future, molecular testing of actively growing PTMCs using cytology specimens could be useful to guide the treatment plan.

Early Diagnosis of Low-Risk Papillary Thyroid Cancer Results Rather in Overtreatment Than a Better Survival

We are witnessing a rapid worldwide increase in the incidence of papillary thyroid carcinoma (PTC) in the last thirty years. Extensive implementation of cancer screening and wide availability of neck ultrasound or other imaging studies is the main reason responsible for this phenomenon. It resulted in a detection of a growing number of clinically asymptomatic PTCs, mainly low-risk tumors, without any beneficial impact on survival. An indolent nature of low-risk PTC, particularly papillary thyroid microcarcinoma (PTMC), and the excellent outcomes raise an ongoing discussion regarding the adequacy of treatment applied. The question of whether PTMC is overtreated or not is currently completed by another, whether PTMC requires any treatment. Current ATA guidelines propose less extensive preoperative diagnostics and, if differentiated thyroid cancer is diagnosed, less aggressive surgical approach and limit indications for postoperative radioiodine therapy. However, in intrathyroidal PTMCs in the absence of lymph node or distant metastases, active surveillance may constitute alternative management with a low progression rate of 1%-5% and without any increase in the risk of poorer outcomes related to delayed surgery in patients, in whom it was necessary. This review summarizes the current knowledge and future perspectives of active surveillance in low-risk PTC.

Active Surveillance of Papillary Thyroid Microcarcinoma: Where Do We Stand?

The recent sharp increase in thyroid cancer incidence is mainly due to increased detection of small papillary thyroid microcarcinoma (PTMC). Due to the indolent nature of the disease, active surveillance (AS) of low-risk PTMCs is suggested as an alternative to immediate surgery to reduce morbidity from surgery. For appropriately selected PTMC patients, AS can be a good management option and surgical intervention can be safely delayed until progression occurs. Many considerations must be taken into account at the time of initiation of AS, including radiological tumor characteristics and clinical characteristics of the patient. A specialized medical team should be assembled to monitor patients during AS with an appropriate follow-up protocol. The fact that some patients require surgery for disease progression after long-term follow-up is a major drawback of the current AS protocol. Evaluation of tumor kinetics by three-dimensional tumor volume measurement during the initial 2-3 years of AS may be helpful for discrimination of PTMCs that need early surgical intervention. In this review, we will discuss the clinical outcomes of surgical intervention and AS, considerations during AS, and unresolved questions about AS.

Active Surveillance for Small Papillary Thyroid Cancer: A Systematic Review and Meta-Analysis

Background: The rapid increase in the incidence of small papillary thyroid carcinoma (PTC) appears to be caused by the detection of small thyroid cancers. Active surveillance (AS) was therefore suggested to overcome this problem. As the results were favorable with low rates of size enlargement and lymph metastasis, the 2015 American Thyroid Association Management Guidelines endorsed AS as an alternative to immediate surgery. As the clinical value of AS is a subject of ongoing active discussions and surveys, we considered a systematic review and meta-analysis to be timely and necessary. Methods: Ovid-MEDLINE and EMBASE databases were searched up to January 5, 2019, for studies reporting patients who were followed up with AS for PTC. Data extraction and methodological quality assessment were performed independently by two radiologists. The primary outcomes were to identify the annual pooled proportions of size enlargement of 3 mm or more and the detection of lymph node metastases at a 5-year follow-up period. These were calculated using an inverse-variance weighting model. An additional outcome was evaluation of the reasons for surgery during AS. Results: The pooled proportion of size enlargement occurring at 5 years was 5.3% [95% confidence interval (CI), 4.4-6.4%], and the pooled proportion of 5-year lymph node metastasis was 1.6% [CI, 1.1-2.4%]. In many subjects undergoing delayed operations, the reasons for operation were often other than those of size enlargement or lymph node metastasis. Conclusions: AS is effective for the management of small PTC, with a low proportion of size enlargement or lymph node metastasis occurring at 5 years. However, a substantial proportion of the causes of delayed surgery were other than size enlargement or lymph node metastasis, and these situations need to be optimally managed.

Active surveillance of low-risk papillary thyroid carcinoma: a promising strategy requiring additional evidence

PURPOSE

Papillary thyroid carcinoma (PTC), the most common malignant tumor of the thyroid, has been criticized as overtreated by some researchers in recent years. Active surveillance (AS) was first proposed at Kuma Hospital in 1993, and popularized in other institutes ever since. We provide a brief review of low-risk PTC active monitoring studies to date, and discuss the advantages of AS and limitations of existing studies.

RESULTS

Most papillary thyroid microcarcinomas do not show significant growth or new lymph node metastasis in a 10-year AS period. Patients who undergo delayed surgery during AS generally have a good prognosis. Tumor progression correlates with age, calcification pattern, and Ki-67 positivity. Serum thyroid stimulating hormone concentration and pregnancy might also influence tumor progression in some studies.

CONCLUSION

Active surveillance for low-risk PTC has shown its safety and feasibility in certain populations. In the future, it is warranted to determine valuable tumor progression predictors and most suitable PTC patients for AS.

Conservative Surveillance Management of Low-Risk Papillary Thyroid Microcarcinoma

Most low-risk papillary thyroid microcarcinomas are indolent. Ten years of active surveillance at Kuma Hospital revealed that only 8.0% of patients showed enlargement of 3 mm or greater, whereas only 3.8% showed nodal metastasis. None, including those who underwent rescue surgery after the detection of progression, showed life-threatening recurrence or distant metastasis, and none died of thyroid carcinoma. Adverse events were significantly more frequent in patients who underwent immediate surgery than in those who had active surveillance. Medical costs were significantly higher. Therefore, active surveillance ought to be the primary method of low-risk papillary thyroid microcarcinoma management.

Histopathological analysis of papillary thyroid carcinoma detected during ultrasound screening examinations in Fukushima

Thyroid ultrasound screening of young residents in Fukushima Prefecture, Japan, showed a high detection rate of papillary thyroid carcinoma (PTC). Detailed morphological analysis of these tumors was not presented to date. This study sets out to evaluate changes in histopathological and invasive characteristics of Fukushima PTC with time after the nuclear accident of March 2011 in all available cases and in different age subgroups. Histological specimens of 115 PTCs from patients aged 18 years or younger at the time of the Fukushima Dai‐ichi Nuclear Power Plant accident, who underwent surgical resection at Fukushima Medical University during 2012‐2016, were reviewed. Patients were divided into those treated during the first 4 years after the accident (n = 78, shorter‐onset) or later (n = 37, longer‐onset). The whole group and 3 age subgroups: children (aged less than 15 years), adolescents (aged from 15 to less than 19 years), and young adults (aged from 19 years) at surgery were analyzed. No statistically significant time‐related changes in tumor structure or invasiveness were found in the whole group or in age‐matched subgroups. Statistically significant age‐related downtrend was observed for intrathyroid spread in the whole group of patients. The absence of temporal changes in tumor morphological characteristics and tumor invasiveness strongly suggests common etiology of the shorter‐ and longer‐onset Fukushima PTCs, which are unlikely related to the effect of exposure to very low doses of radiation.

Active Surveillance as First-Line Management of Papillary Microcarcinoma

Papillary thyroid microcarcinoma (PMC) is defined as papillary thyroid carcinoma ≤10 mm. Active surveillance of PMC without high-risk features, such as clinical node metastasis, distant metastasis, and clinical evidence of significant extrathyroid extension, was initiated in two Japanese hospitals in the mid-1990s. This strategy was incorporated into guidelines in Japan in 2010 and in the United States in 2015. In studies conducted by the two hospitals, most PMCs grew very slowly or did not grow, and none of the patients during active surveillance showed distant metastasis or died of thyroid carcinoma. Furthermore, none of the patients who underwent surgery after progression signs were detected showed significant recurrence. Therefore, we conclude that active surveillance should be the first line in management of low-risk PMC, because it is safer and less costly than immediate surgery. Active surveillance helps in avoiding adverse events of surgery and is an economical strategy.

Predictive factors of lateral lymph node metastasis in solitary papillary thyroid microcarcinoma without gross extrathyroidal extension

BACKGROUND

Solitary papillary thyroid microcarcinoma (PTMC) without gross extrathyroidal extension (ETE) were the main candidates for active surveillance (AS). Predictive factors of lateral lymph node metastasis (LLNM) in solitary PTMC without gross ETE were essential but still unknown.

METHODS

Altogether, 171 patients of solitary PTMC without gross ETE were enrolled in our study and divided into two groups. Group A: 123 patients without lateral lymph node dissection (LLND) were considered to be LLNM negative because there was no lateral recurrence by at least 8-year follow up for all patients. Group B: 48 patients with LLND were considered to be LLNM positive which confirmed by postoperative pathology.

RESULTS

Multivariate logistic regression showed male gender, upper location of tumor and diameter of tumor ≥7 mm to be predictive factors (odds ratio = 4.237 [confidence interval (CI) 1.365-13.149, p = 0.012; odds ratio = 2.933 [CI 1.117-7.700, p = 0.029; odds ratio = 4.557 [CI 1383-15.016, p = 0.013) for LLNM in solitary PTMC patients without gross ETE. Multiple level metastasis happened in 29 (60.42%) cases while single level metastasis in 19 (39.58%). Within the lateral cervical lymph node chain, level Ⅲ nodes were consistently the most frequently involved (38/48, 79%), following by level Ⅳ (27/48, 56%), level Ⅱ (25/48, 52%) and level V (5/48, 10%). Most interesting, there are 12 (12/48, 25%) skip metastatic (positive in lateral neck and negative in central neck) patients among LLNM positive group.

CONCLUSIONS

Male gender, upper location of tumor and diameter of tumor ≥0.7 cm to be predictive factors of LLNM in solitary PTMC without gross ETE.

Risk factors associated with intrathyroid extension of thyroid microcarcinomas

PURPOSE

The aims of this study were to investigate the rate of intrathyroid extension of papillary thyroid microcarcinoma (PTMC) in patients operated for benign thyroid disease and to identify independent risk factors associated with it.

METHODS

A retrospective study of 301 patients operated for benign thyroid diseases (hyperthyroid diseases, multinodular goitre, Hashimoto thyroiditis and benign thyroid tumours) was performed at a high-volume endocrine surgery unit of a tertiary referral academic hospital, in a 5-year period. These patients had a PTMC incidentally discovered on definite histopathological findings following total or near-total thyroidectomy. Since distinguishing between intrathyroid extension of PTMC as the result of intrathyroid dissemination or as the result of multicentricity is challenging, we observed them together as multifocality. In statistical analysis, we used standard descriptive statistics and univariate and multivariate logistic regression analysis to determine independent risk factors associated with multifocality.

RESULTS

In our study, there were 85.4% females and 14.6% males with a median age of 54 years. A multinodular goitre (32.5%) was the most common indication for an operation. Most patients (68.4%) had a PTMC that was 5 mm or smaller. The most frequent histological variants of PTMC were the follicular variant (52.8%), followed by the papillary variant (22.6%) and the mixed follicular-papillary variant (18.6%). A multifocal PTMC was present in 26.6% of cases. An independent protective factor for multifocality of PTMC was a thyroid gland that weighed more than 38 g (OR 0.55, 95% CI 0.31-0.97, p = 0.039). Size of PTMC greater than 5 mm was an independent risk factor for a multifocal PTMC (OR 3.26, 95% CI 1.85-5.75, p = 0.000). Finally, the mixed follicular-papillary variant of PTMC represents an independent risk factor for a multifocal PTMC (OR 2.42, 95% CI 1.09-5.36, p = 0.030).

CONCLUSIONS

Intrathyroid extension is present in more than a quarter of PTMCs found in patients operated for benign thyroid disease. Independent risk factors for intrathyroid extension are size of PTMC greater than 5 mm and the mixed follicular-papillary variant of PTMC, while a large thyroid gland is an independent protective factor.

Insights into the Management of Papillary Microcarcinoma of the Thyroid

BACKGROUND

Rapid increases in the incidence of thyroid carcinoma with stable mortality rates from thyroid carcinoma have been reported from many countries, and these increases are thought to be due mostly to the increased detection of small papillary thyroid carcinomas (PTCs), including papillary microcarcinomas (PMCs; i.e., PTCs ≤10 mm). Some researchers have suggested that small PTCs have been overdiagnosed and overtreated. In Japan, the active surveillance of patients with low-risk PMCs was initiated by Kuma Hospital (1993) and Tokyo's Cancer Institute Hospital (1995) based on the extremely higher incidences of both latent thyroid carcinomas in autopsy studies and small PTCs detected in mass screening studies using ultrasound examinations compared to the prevalence of clinical thyroid carcinomas.

METHODS

The above two institutions' data are summarized regarding the active surveillance of low-risk PMCs, and future prospects for their management are discussed.

RESULTS

At 10-year observations in the Kuma Hospital series of 1235 patients, only 8% and 3.8% of the PMC patients showed size enlargement by ≥3 mm and the novel appearance of node metastasis, respectively. In contrast to clinical PTC, PMCs are most unlikely to grow in older patients (≥60 years). In the Kuma Hospital series, the 974 patients who underwent immediate surgery had significantly higher incidences of unfavorable events than the 1179 patients who chose active surveillance. The total cost of immediate surgery, including the costs for salvage surgery and postoperative care for 10 years, was 4.1 times the total cost of 10-year management by active surveillance. Only 8% of the 51 PMC patients showed tumor enlargement during pregnancy, and the rescue surgeries after delivery were successful. In the Cancer Institute Hospital series of 230 patients with 300 lesions, only 7% and 1% of the patients showed size enlargement and novel node metastasis, respectively, and that institution's analysis also revealed that macroscopic or rim calcification and poor vascularity were correlated with non-progressing disease. In both series, none of the patients who underwent rescue surgery after progression signs were detected showed significant recurrence or died of PTC.

CONCLUSION

Active surveillance of low-risk PMC can be the first-line management. Interestingly, older patients with low-risk PMCs are the best candidates for active surveillance.

Active Surveillance for Papillary Thyroid Microcarcinoma: Challenges and Prospects

Active surveillance (AS) can be considered as an alternative to immediate surgery in low-risk papillary thyroid microcarcinoma (PTMC) without clinically apparent lymph nodes, gross extrathyroidal extension (ETE), and/or distant metastasis according to American Thyroid Association. However, in the past AS has been controversial, as evidence supporting AS in the management of PTMC was scarce. The most prominent of these controversies included, the limited accuracy and utility of ultrasound (US) in the detection of ETE, malignant lymph node involvement or the advent of novel lymph node malignancy during AS, and disease progression. We summarized publications and indicated: (1) US, performer-dependent, could not accurately diagnose gross ETE or malignant lymph node involvement in PTMC. However, the combination of computed tomography and US provided more accurate diagnostic performance, especially in terms of selection sensitivity. (2) Compared to immediate surgery patients, low-risk PTMC patients had a slightly higher rate of lymph node metastases (LNM), although the overall rate for both groups remained low. (3) Recent advances in the sensitivity and specificity of imaging and incorporation of diagnostic biomarkers have significantly improved confidence in the ability to differentiate indolent vs. aggressive PTMCs. Our paper reviewed current imagings and biomarkers with initial promise to help select AS candidates more safely and effectively. These challenges and prospects are important areas for future research to promote AS in PTMC.

Active Surveillance of Papillary Thyroid Microcarcinoma: A Mini-Review from Korea

In Korea, the incidence of thyroid cancer increased explosively in the early 2000s, and reached a plateau in the early 2010s. Most cases of newly diagnosed thyroid cancer are small indolent microcarcinoma and could be good candidates for active surveillance (AS) instead of immediate surgery. Many considerations must be taken into account for establishing selection criteria for candidates for AS of papillary thyroid microcarcinoma (PTMC), including the characteristics of the tumor, the patient, and the medical team. If possible, AS of PTMC should be a part of a prospective clinical trial to ensure long-term safety and to identify clinical and/or molecular markers of the progression of PTMC. In this review, we discuss lessons regarding surgical interventions for PTMC, and then describe the concept, application, caveats, unanswered questions, and future perspectives of AS of PTMC. For appropriately selected patients with PTMC, AS can be a good alternative to immediate surgery.

Low-risk papillary microcarcinoma of the thyroid: A review of active surveillance trials

Papillary microcarcinoma (PMC) of the thyroid is defined as papillary thyroid carcinoma (PTC) measuring ≤1 cm. Many autopsy studies on subjects who died of non-thyroidal diseases reported latent small thyroid carcinoma in up to 5.2% of the subjects. A mass screening study for thyroid cancer in Japanese adult women detected small thyroid cancer in 3.5% of the examinees. This incidence was close to the incidence of latent thyroid cancer and more than 1000 times the prevalence of clinical thyroid cancer in Japanese women reported at that time. The question of whether it was correct to treat such PMCs surgically then arose. In 1993, according to Dr. Miyauchi's proposal, Kuma Hospital initiated an active surveillance trial for low-risk PMC as defined in the text. In 1995, Cancer Institute Hospital in Tokyo, Japan, started a similar observation trial. The accumulated data from the trials at these two institutions strongly suggest that active surveillance (i.e., observation without immediate surgery) can be the first-line management for low-risk PMC. Although our data showed that young age and pregnancy might be risk factors of disease progression, we think that these patients can also be candidates for active surveillance, because all of the patients who showed progression signs were treated successfully with a rescue surgery, and none of them died of PTC. In this review, we summarize the data regarding the active surveillance of low-risk PMC as support for physicians and institutions that are considering adopting this strategy.

Total thyroidectomy may be more reasonable as initial surgery in unilateral multifocal papillary thyroid microcarcinoma: a single-center experience

BACKGROUND

The extent of surgery in patients with unilateral multifocal papillary thyroid microcarcinoma (UMPTMC) remains to be controversial. Aimed to improve surgical management of UMPTMC, this study was performed to identify the recurrence of UMPTMC and analyze its predictive factors.

METHODS

This study was approved by the Ethical Committee of The First Hospital of the Jilin University, and written informed consent was given by participants for their clinical records to be used in this study. We retrospectively analyzed a total of 97 consecutive patients who underwent initial surgery for the treatment of UMPTMC at The First Hospital of Jilin University, between October 2005 and October 2006.

RESULTS

Altogether, 97 patients of UMPTMC have been enrolled in our study, in which 57 cases were performed with hemithyroidectomy (HT) while other 40 cases with total thyroidectomy (TT). The sum diameter of all tumors >1 cm was more frequent in HT group than in TT group (40.35 vs 20%; p = 0.046). Positive central lymph nodes were found more frequently in the TT patients than in the HT patients (80 vs 59.65%; p = 0.046). Tumor recurrence was seen more frequently in the HT cases than in the TT cases (26 vs 5%; p = 0.007). The disease-free survival period was significantly shorter for the HT patients than for the TT patients (p = 0.0059 by the log-rank test). The disease-free survival rates at 5 and 10 years were 91.23 and 73.68%, respectively, in the HT group and 100 and 92.5%, respectively, in the TT group. Univariate analysis by Cox's proportional hazards method showed male gender, sum diameter of all tumors >1 cm, and central lymph node metastases (CLNM) to be risk factors for recurrence of HT patients. Male gender and sum diameter >1 cm were factors identified for multivariate analysis by Cox's proportional hazards method which yielded risk ratios of 3.037 [CI 1.026-8.988; p = 0.045] and 5.475 [CI 1.389-21.572; p = 0.015] in the HT group.

CONCLUSIONS

In summary, with an increased risk of recurrence, TT may be more reasonable as initial surgery in UMPTMC, especially with male gender and total tumor diameter greater than 1 cm.