Insights and clinical questions about the active surveillance of low-risk papillary thyroid microcarcinomas [Review]

The Preferred Route for the Diagnosis and Management of Thyroid Carcinoma Among the General Population in Saudi Arabia

BACKGROUND

 Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. Papillary thyroid microcarcinoma (PTMC) is a specific subgroup of PTC. Given their small size, PTMCs are often asymptomatic and behave benignly. This puts physicians in a challenging situation about how to prevent overdiagnosis and overtreatment of PTMC. This study aimed to assess the preferences regarding the route of PTMC diagnosis and treatment among Saudi Arabia's general population.

METHODS

 This is a cross-sectional questionnaire-based-study conducted among the general population in Saudi Arabia. The target subjects were the general population of Saudi Arabia both genders and different age groups from various regions of Saudi Arabia (Western, Central, Eastern, Southern, and North). Participants who did not complete the questionnaire or did not agree to participate were excluded. A self-administered questionnaire was distributed on different social media platforms to collect data from different regions. Data analysis was conducted by using Statistical Package for the Social Sciences (SPSS) 24.0 version (IBM Inc., Chicago, USA) statistical software. A Chi-square test was used to compare categorical variables.

RESULTS

 A total of 1,428 participants were included. The majority of them were females (64.4%), and most of them were aged between 19 and 25 years. Moreover, we found that 4.8% of the study population had a medical history of thyroid cancer. Our results revealed that more than half of respondents (54.6%) would select surgical operation immediately if they have a thyroid nodule less than 1 cm in maximal diameter, which turns out to be a PTC. The vast majority of participants (90.1%) would prefer to do cytologic confirmation immediately if they have a thyroid nodule less than 1 cm in maximal diameter, which has suspicious characteristics of PTC in neck ultrasound examination. Regarding PTMC operation, 59.8% of responders were more concerned about complications than recurrences. We found that neither age nor gender significantly affects decision-making for management or operative extent for PTC. There was a significant difference between age and decision-making for the diagnosis of suspicious thyroid nodules (p value = 0.041).

CONCLUSION

 Our results concluded that most of the participants preferred to select immediate surgery and cytologic confirmation regarding the management and diagnosis of PTC. More research is advised. The need to inform patients about their disease state and treatment options should be highlighted more.

Study on Changes in Immune Function After Microwave Ablation of Papillary Thyroid Microcarcinoma

Background

In recent years, papillary thyroid microcarcinoma (PTMC) has been a main cause of the high incidence of thyroid carcinoma. No existing study has reported whether microwave ablation (MWA) affects patients' immunity. Therefore, this study explored the effects of MWA treatment on the immune functions of patients with PTMC.

Methods

This study included 50 patients diagnosed with PTMC who received MWA treatment under ultrasound guidance at the ultrasound department of our hospital from January 2019 to October 2020. Changes in immune function after MWA treatment in PTMC patients were detected by T lymphocyte subsets and cytokines secreted by T helper cells.

Results

At 1 day and 2 weeks after MWA treatment, the proportions of CD3⁺, CD4⁺ and CD4⁺/CD8⁺ T lymphocyte subsets and the levels of the cytokines interleukin (IL)-2 and interferon (IFN)-γ in the peripheral blood of the patients were significantly higher than those before MWA treatment (P<0.05). The levels of CD8⁺ T lymphocytes, tumour necrosis factor (TNF)-α, IL-4, IL-6, IL-10 and IL-17A were not significantly different from those before MWA treatment (P>0.05). One month after MWA treatment, the proportions of CD3⁺, CD4⁺, CD8⁺ and CD4⁺/CD8⁺ T lymphocytes and the levels of the cytokines IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α and IL-17A were not significantly different from those before MWA treatment (P>0.05).

Conclusion

The immune functions of patients with PTMC are temporarily enhanced after MWA treatment, which has important clinical significance for patients' anti-PTMC ability.

Ultrasound-Guided Percutaneous Laser Ablation of the Thyroid Gland in a Swine Model: Comparison of Ablation Parameters and Ablation Zone Dimensions

BACKGROUND

To compare laser ablation (LA) zone dimensions at two predetermined energy parameters to cover a theoretical 10 mm zone + 2 mm margin in a thyroid swine model.

METHODS

Approval of the Institutional Animal Care and Use Committee was obtained. After hydrodissection, an ultrasound-guided LA (Elesta Echolaser X4 with Orblaze technology, 1064 nm) was performed in the periphery of the thyroid in 10 swine. Two cohorts were established to ablate a region of 10mm diameter with 2mm margin based on manufacturer's ex vivo data (n= 5 at 3W/1400J and n= 5 at 3W/1800J). The ablation zone was measured on contrast-enhanced computed tomography (CT) and compared to the pathological specimen. Euthanasia was performed 48 hours following ablation.

RESULTS

All ablations in the 3W/1800J group achieved a diameter of 12 mm ± 1 mm in three dimensions. In the 3W/1400J group, 1 ablation reached 12 mm ± 1 mm in 2 dimensions and 4 ablations reached this size in one dimension. Maximum diameter was higher in the 3W/1800J compared to the 3W/1400J group, both on histology (1.46 cm ± 0.05 vs. 1.1 cm ± 0.0, p< 0.01) and CT (1.52 cm ± 0.04 vs. 1.18 cm ± 0.04, p< 0.01). Similar results were obtained regarding volumes, both on histology (1.12 mL ± 0.13 vs. 0.57 mL ± 0.06, p< 0.01) and CT (1.24 mL ± 0.13 vs. 0.59 mL ± 0.07, p< 0.01). Histology showed coagulation necrosis and correlated well with CT measurements.

CONCLUSION

Optimal parameters to obtain a LA zone of 10 mm with 2 mm margin utilizing a single needle are 3W/1800J.

Thyroid lobectomy as a cost-effective approach in low-risk papillary thyroid cancer versus active surveillance

BACKGROUND

An ongoing debate exists over the optimal management of low-risk papillary thyroid cancer. The American Thyroid Association supports the concept of active surveillance to manage low-risk papillary thyroid cancer; however, the cost-effectiveness of active surveillance has not yet been established. We sought to perform a cost-effectiveness analysis comparing active surveillance versus surgical intervention for patients in the United States.

METHODS

A Markov decision tree model was developed to compare active surveillance and thyroid lobectomy. Our reference case is a 40-year-old female who was diagnosed with unifocal (<15 mm), low-risk papillary thyroid cancer. Probabilistic outcomes, costs, and health utilities were determined using an extensive literature review. The willingness-to-pay threshold was set at $50,000/quality-adjusted life year gained. Sensitivity analyses were performed to account for uncertainty in the model's variables.

RESULTS

Lobectomy provided a final effectiveness of 21.7/quality-adjusted life years, compared with 17.3/quality-adjusted life years for active surveillance. Furthermore, incremental cost effectiveness ratio for lobectomy versus active surveillance was $19,560/quality-adjusted life year (<willing-to-pay threshold of $50,000/quality-adjusted life year), and thus surgical intervention proved to be cost-effective in patients between 40 and 69 years old. Further analysis revealed that, at the age of 69 years, active surveillance is more cost-effective than lobectomy, with a final effectiveness of 17.3/quality-adjusted life years. Compared to active surveillance, the incremental cost effectiveness ratio for lobectomy at the age of 69 was $27,235/quality-adjusted life year, which decreases quality-adjusted life years by 1.5.

CONCLUSION

Lobectomy is a cost-effective strategy in middle-aged patients with low-risk papillary thyroid cancer. In contrast, active surveillance is cost-effective beginning at the age of 69. Identification of such nuances can help physicians and patients determine the best, most individualized long-term management strategy for low-risk papillary thyroid cancer.

Active Surveillance as an Effective Management Option for Low-Risk Papillary Thyroid Microcarcinoma

Active surveillance (AS) for low-risk papillary thyroid microcarcinoma (PTMC) has been accepted worldwide as safe and effective. Despite the growing acceptance of AS in the management of low-risk PTMCs, there are barriers to AS in real clinical settings, and it is important to understand and establish appropriate AS protocol from initial evaluation to follow-up. PTMC management strategies should be decided upon after careful consideration of patient and tumor characteristics by a multidisciplinary team of thyroid cancer specialists. Patients should understand the risks and benefits of AS, participate in decision-making and follow structured monitoring strategies. In this review, we discuss clinical outcomes of AS from previous studies, optimal indications and follow-up strategies for AS, and unresolved questions about AS.

Differentiated Thyroid Cancer: A Health Economic Review

Simple Summary

This review reflects on health economic considerations associated with the increasing diagnosis and treatment of differentiated thyroid cancer. Analysis of different relevant health economic topics, such as overdiagnosis, overtreatment, surgical costs, and costs of follow-up are being addressed. Several unanswered research questions such as optimising molecular markers for diagnosis, active surveillance of primary tumours, and improved risk stratification and survivorship care all influence future healthcare expenditures.

Abstract

The incidence of differentiated thyroid cancer (DTC) is rising, mainly because of an increased detection of asymptomatic thyroid nodularity revealed by the liberal use of thyroid ultrasound. This review aims to reflect on the health economic considerations associated with the increasing diagnosis and treatment of DTC. Overdiagnosis and the resulting overtreatment have led to more surgical procedures, increasing health care and patients’ costs, and a large pool of community-dwelling thyroid cancer follow-up patients. Additionally, the cost of thyroid surgery seems to increase year on year even when inflation is taken into account. The increased healthcare costs and spending have placed significant pressure to identify potential factors associated with these increased costs. Some truly ground-breaking work in health economics has been undertaken, but more cost-effectiveness studies and micro-cost analyses are required to evaluate expenses and guide future solutions.

Lateral Lymph Node Metastases in T1a Papillary Thyroid Carcinoma: Stratification by Tumor Location and Size

OBJECTIVE

To analyze the incidence and risk factors for lateral lymph node metastases (LNMs) in T1a papillary thyroid carcinoma (PTC) with a focus on tumor location and size.

MATERIALS AND METHODS

The incidence of lateral LNM in 345 cases of T1a PTC was retrospectively analyzed. Univariate and multivariate analyses were performed to assess the relationships between lateral LNM and clinicopathological characteristics.

RESULTS

The incidence of skip metastasis to lateral LNM in T1a PTC located in the upper lobe was 12.1% (8/66). Logistic regression analysis indicated tumor size >5 mm (OR = 5.04, 95% CI = 1.79 to 14.18, P = 0.002), upper lobe location (OR = 7.68, 95% CI = 3.05-19.34, P < 0.001) and the number of central neck LNM (<2: OR = 24.79, 95% CI = 8.23-74.60, P < 0.001; ≥2: OR = 4.99, 95% CI = 1.95-12.73, P < 0.001) were independently associated with lateral LNM. Comparing the lateral and central LNM stratification based on tumor location revealed that both the incidences of lateral (33.3%) and central (30.3%) LNM of T1a PTC located in the upper lobe were higher than those of T1a PTC located in the middle and lower lobes. Of T1a PTC located in the upper lobe, the incidence of lateral LNM was 33.3% (22/66), which was higher than that [30.3% (20/66)] of central LNM. This finding is reversed in all T1a PTC cases and T1a PTC cases with tumor located in the middle and lower lobes.

CONCLUSION

A particularly high likelihood of lateral LNM was observed in T1a PTC patients with tumor located in the upper lobe of the thyroid gland, especially the tumor >5 mm in size, which could be considered a risk factor for lateral LNM in the clinical management of T1a PTC.

Is Less More? A Microsimulation Model Comparing Cost-effectiveness of the Revised American Thyroid Association's 2015 to 2009 Guidelines for the Management of Patients With Thyroid Nodules and Differentiated Thyroid Cancer

OBJECTIVE

To assess relative clinical and economic performance of the revised American Thyroid Association (ATA) thyroid cancer guidelines compared to current standard of care.

BACKGROUND

Diagnosis of thyroid cancer in the United States has tripled whereas mortality has only marginally increased. Most patients present with small papillary carcinomas and have historically received at least a total thyroidectomy as a treatment. In 2015, the ATA released the revised guidelines recommending an option for active surveillance (AS) of small papillary thyroid carcinoma and thyroid lobectomy for larger unifocal tumors.

METHODS

We created a Markov microsimulation model to evaluate the performance of the ATA's 2015 guidelines compared to the ATA's 2009 guidelines. We modeled a cohort of simulated patients with demographic and thyroid nodule characteristics representative of those presenting clinically in the United States. Outcome measures include life expectancy, quality-adjusted life years, costs, and frequency of surgical adverse events.

RESULTS

In our base case analysis, the ATA 2015 strategy dominates the ATA 2009 strategy. The ATA 2015 strategy delivers greater discounted average quality-adjusted life years (13.09 vs 12.43) at a lower discounted average cost ($14,752 vs $20,126). Deaths due to thyroid cancer under the 2015 strategy are higher than the 2009 strategy but this is offset by a reduction in surgical deaths, leading to greater average life expectancy under the ATA 2015 strategy. The optimal strategy is sensitive to patients who experience a greater decrement in quality of life while undergoing AS.

CONCLUSIONS

The ATA 2015 Guidelines represent a cost-effective strategy regarding AS and extent of surgery.

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.

Risk-oriented concept of treatment for intrathyroid papillary thyroid cancer

Adapting treatment and follow-up according to the risk of recurrence and/or death from thyroid cancer is a relatively recent concept of "personnalized" medicine, developed particularly to avoid overtreatment of low-risk thyroid cancer which represents the majority of thyroid cancers diagnosed in the world today. For low-risk thyroid cancer, this decrease in extent of treatment involves the extent of surgery-total thyroidectomy, lobectomy or no surgery with active surveillance-but also the indications, doses and methods of stimulation when or if administering radioactive iodine (RAI), the indication for suppressive thyroxin therapy and the extent and modalities for follow-up that should be adapted to the risk of recurrence. The aim is to optimize medical resources and quality of life, particularly for low-risk patients whose life expectancy is that of the general population.

Determine the Optimal Extent of Thyroidectomy and Lymphadenectomy for Patients With Papillary Thyroid Microcarcinoma

Background: The optimal extent of surgery, including lymph node dissection, remains controversial in papillary thyroid microcarcinoma (PTMC). Determining risk factors of central lymph node metastasis (CLNM) and recurrence-free survival (RFS) may help surgeons determine individualized surgery. Methods: A total of 353 patients with PTMC were retrospectively analyzed, including 263 with overt PTMC and 90 with incidental PTMC. The recurrence rates between different extents of thyroidectomy were compared. The relationship between CLNM and clinicopathologic factors was analyzed. The Cox regression model was used to determine the risk factors for RFS. Results: Lobectomy/total thyroidectomy (TT) with central neck dissection (CND) was performed in 263 overt PTMC patients, and lobectomy/partial thyroidectomy was performed in 90 incidental PTMC patients. In 263 overt PTMC patients, 93 (26.3%) had CLNM only and 13 (3.7%) had both CLNM and lateral lymph node metastases (LLNM). Multifocal PTMC patients who underwent lobectomy had a higher rate of thyroid bed and lymph node recurrence than patients who underwent TT (P < 0.05). Independent predictors for CLNM were age <45 years, tumor size >5 mm and presence of extrathyroidal extension (ETE). Tumor size >5 mm, multifocality, presence of ETE, presence of CLNM, and presence of LLNM were the significant factors related to the RFS. Conclusion: Fine-needle aspiration biopsy is advised to distinguish incidental PTMC from the benign nodules. For multifocal PTMC patients, TT should be performed to reduce recurrence. Routine prophylactic CND can be recommended in PTMC patients with independent risk factors of CLNM. Aggressive surgery and close follow-up are essential for patients with risk factors of RFS.

Can Active Surveillance be an Alternative to Surgery in Papillary Thyroid Microcarcinoma?: The Current Situation Worldwide

Papillary thyroid carcinoma is the most common endocrine malignancy. Papillary thyroid microcarcinomas (PTMCs) are tumors with a size of ≤1 cm. The biological behavior of these tumors differs due to the presence of their aggressive features. The prognosis of PTMCs with high-risk features, such as clinical node metastasis, distant metastasis, and significant extrathyroidal extension to the tracheal or recurrent laryngeal nerve invasion, is poor, even if a sufficient immediate surgery is performed at diagnosis. However, PTMCs without these aggressive features are low-risk tumors because of their indolent and slow growth behaviors. The increase in thyroid cancer incidence is mostly a result of overdiagnosis of small low-risk PTMCs with indolent clinical course. Despite the sudden increase in thyroid cancer incidence worldwide, cancer mortality did not increase. Although the traditional treatment strategy for PTMC is immediate surgery at diagnosis, because of the rather low disease-specific mortality rate, low recurrence rate, and potential risk for postoperative complications, active surveillance has been proposed recently as an alternative option for PTMCs without invasion, metastasis, or cytological or molecular characteristics. The recent data support that active surveillance of low-risk PTMC should be the initial treatment modality, because only a small percentage of low-risk PTMCs show signs of progression, and delayed surgery has not caused significant recurrence. However, recent management guidelines are shifting toward more conservative treatments, such as active surveillance. Although there is an increase in the number of studies related to active surveillance, prospective studies have been mostly from academic referral centers in Japan. The world still needs class 1 evidence extended prospective studies originating from different geographic regions. Active surveillance may be a good alternative to immediate surgery for appropriately selected patients with PTMC.

Comparative study on operative trauma between microwave ablation and surgical treatment for papillary thyroid microcarcinoma

AIM

To compare the effect and postoperative trauma of ultrasound-guided percutaneous microwave ablation and surgical resection in the treatment of papillary thyroid microcarcinoma (PTMC).

METHODS

Eighty-seven patients with PTMC treated at Fudan University affiliated Shanghai Fifth People’s Hospital were enrolled as subjects. The patients were divided into a microwave ablation group (41 cases) and a surgical group (46 cases). The operative time, intraoperative blood loss, length of hospital stay, serum C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), thyroid-related hormonal changes, and complications 7 d and 30 d after surgery were observed.

RESULTS

The operative time, intraoperative blood loss, and length of hospital stay in the surgical group were significantly higher than those in the microwave ablation group (P < 0.05). The levels of CRP, IL-6, and TNF-α in the surgical group were significantly higher than those in the microwave ablation group (P < 0.05). The free triiodothyronine (FT3) and free thyroxin (FT4) levels in the surgical group were significantly lower than those in the microwave ablation group (P < 0.05). However, the postoperative thyroid stimulating hormone (TSH) level was significantly higher than that in the microwave ablation group (P < 0.05). There were significant interactions between the FT3, FT4, and TSH 7 d and 30 d after operation and the treatment methods (P < 0.05). There was no significant difference in the complications between the two groups (P > 0.05).

CONCLUSION

Microwave ablation for papillary microcarcinoma of the thyroid gland has less trauma to the body, quicker recovery, and no scars. It can effectively shorten the length of hospital stay and improve the quality of life of patients.

Diagnostic Performance of Ultrasound-Based Risk-Stratification Systems for Thyroid Nodules: Comparison of the 2015 American Thyroid Association Guidelines with the 2016 Korean Thyroid Association/Korean Society of Thyroid Radiology and 2017 American College of Radiology Guidelines

PURPOSE

The aim of this study was to compare the diagnostic performance of ultrasound (US)-based risk-stratification systems for thyroid nodules in the 2015 American Thyroid Association (ATA) guidelines with those of the 2016 Korean Thyroid Association (KTA)/Korean Society of Thyroid Radiology (KSThR) and 2017 American College of Radiology (ACR) guidelines.

METHODS

From June 2013 to May 2015, a total of 902 consecutive thyroid nodules were enrolled in four institutions, and their US features were retrospectively reviewed and classified using the categories defined by the three guidelines. The malignancy risk of each category, as defined by all three risk-stratification systems, was calculated, and the diagnostic performance of the fine-needle aspiration (FNA) indications of the ATA guidelines were compared to those of the KTA/KSThR and ACR guidelines.

RESULTS

Of all nodules, 636 (70.5%) were benign and 266 (29.5%) malignant. The calculated malignancy risks for ATA categories 5, 4, 3, 2, and 1 nodule(s) were 71.7, 21.5, 2.6, 3.8, and 0%. Of all nodules, 7.6% (69/902) did not meet the ATA pattern criteria, but the malignancy risk was calculated to be 10.1% (7/69). The ATA guidelines afforded significantly higher diagnostic sensitivity (95.0%) than the ACR guidelines (80.2%; p = 0.001) but a lower specificity (38.1 vs. 68.9%; p < 0.001). On the other hand, the ATA guidelines exhibited a lower diagnostic sensitivity than the KTA/KSThR guidelines (100.0%; p = 0.07) but a higher specificity (28.2%; p < 0.001). The unnecessary FNA rate was the lowest when the ACR guidelines were used (25.8%), followed by the ATA (51.2%) and KTA/KSThR (59.4%) guidelines.

CONCLUSION

The 2015 ATA guidelines afford relatively moderate sensitivity and an unnecessary FNA rate for thyroid cancer detection compared to the 2016 KTA/KSThR and 2017 ACR guidelines. US practitioners require a deep understanding of the benefits and risks of the US-based FNA criteria of different guidelines and potential impact on the diagnosis of low-risk thyroid cancers.

Circulating BRAFV600E Levels Correlate with Treatment in Patients with Thyroid Carcinoma

BACKGROUND

BRAF^V600E is the most common mutation in papillary thyroid carcinoma (PTC) and can be associated with aggressive disease. Previously, a highly sensitive blood RNA-based BRAF^V600E assay was reported. The objective of this study was to assess the correlation of BRAF^V600E circulating tumor RNA levels with surgical and medical treatment.

METHODS

Circulating BRAF^V600E levels were assessed in (i) a murine model of undifferentiated (anaplastic) thyroid carcinoma with known BRAF^V600E mutation undergoing BRAF^V600E-inhibitor (BRAFi) treatment, and (ii) in 111 patients enrolled prior to thyroidectomy (n = 86) or treatment of advanced recurrent or metastatic PTC (n = 25). Blood samples were drawn for BRAF^V600E analysis before and after treatment. Testing characteristics were assessed and positivity criteria optimized. Changes in blood BRAF^V600E values were assessed and compared to clinical characteristics and response to therapy.

RESULTS

In a murine model of anaplastic thyroid carcinoma with BRAF^V600E mutation, blood BRAF^V600E RNA correlated with tumor volume in animals treated with BRAFi. In tissue BRAF^V600E-positive (n = 36) patients undergoing initial surgery for PTC, blood BRAF^V600E levels declined postoperatively (median 370.0-178.5 fg/ng; p = 0.002). In four patients with metastatic or poorly differentiated thyroid carcinoma receiving targeted therapies, blood BRAF^V600E declined following therapy and corresponded with radiographic evidence of partial response or stable disease.

CONCLUSIONS

This study shows the correlation of blood BRAF^V600E levels in response to treatment in both an established animal model of thyroid cancer and in patients with BRAF^V600E-positive tumors with all stages of disease. This assay represents an alternative biomarker in patients with positive thyroglobulin antibodies, and tumors, which do not express thyroglobulin.

Long-term efficacy of ultrasound-guided low power microwave ablation for the treatment of primary papillary thyroid microcarcinoma: a 3-year follow-up study

PURPOSE

To evaluate the safety and efficacy of ultrasound-guided low-power microwave ablation (MWA) for the treatment of papillary thyroid microcarcinoma (PTMC) with a 3-year follow-up.

METHODS

A total of 21 nodules diagnosed as PTMC from the 15 patients were performed with MWA at a power of 20 W. The images of the nodules were recorded by ultrasound before MWA and 1, 3, 6, 12 months after MWA, and every 6 months thereafter, respectively. The volumes of the nodules were compared before MWA and at each follow-up point after MWA. The volume reduction rate (VRR) of nodules was also calculated.

RESULTS

The mean volume of the nodules was 134.3 ± 129.8 mm³ initially (the range was 7.4-423.8 mm³), which decreased significantly to 2.3 ± 10.5 mm³ (the range was 0-48.1 mm³) of the ablation area (P = 0.000) at the follow-up point of 36 months with a mean VRR as 98.78 ± 5.61% (the range was 74.28-100%). During the follow-up period (the range was 36-48 months), 20 of the 21 nodules were completely absorbed and no recurrent nodule was found.

CONCLUSIONS

After a long-term follow-up of 3 years, the low power MWA showed a good safety and efficacy for the treatment of PTMC. In addition to surgery and active surveillance, MWA might be another alternative for patients with PTMC.

Validation of Three Scoring Risk-Stratification Models for Thyroid Nodules

BACKGROUND

To minimize potential harm from overuse of fine-needle aspiration, Thyroid Imaging Reporting and Data Systems (TIRADSs) were developed for thyroid nodule risk stratification. The purpose of this study was to perform validation of three scoring risk-stratification models for thyroid nodules using ultrasonography features, a web-based malignancy risk-stratification system, and a model developed by the Korean Society of Thyroid Radiology and the American College of Radiology.

METHODS

Using ultrasonography images, radiologists assessed thyroid nodules according to the following criteria: internal content, echogenicity of the solid portion, shape, margin, and calcifications. A total of 954 patients (M_age = 50.8 years; range 13-86 years) with 1112 nodules were evaluated at the authors' institute from January 2013 to December 2014. The discrimination ability of the three models was assessed by estimating the area under the receiver operating characteristic curve. Additionally, Hosmer-Lemeshow goodness-of-fit statistics (calibration ability) were used to evaluate the agreement between the observed and expected number of nodules that were benign or malignant.

RESULTS

Thyroid malignancy was present in 37.2% (414/1112) of nodules. According to the 14-point web-based scoring risk-stratification system, malignancy risk ranged from 4.5% to 100.0% and was positively associated with an increase in risk scores. The areas under the receiver operating characteristic curve of the validation set were 0.884 in the web-based model, 0.891 in the Korean Society of Thyroid Radiology model, and 0.875 in the American College of Radiology model. The Hosmer-Lemeshow goodness-of-fit test indicated that the web-based scoring system showed the best-calibrated result, with a p-value of 0.078.

CONCLUSION

The three scoring risk-stratification models using the ultrasonography features of thyroid nodules to stratify malignancy risk showed acceptable predictive accuracy and similar areas under the curve. The web-based scoring system demonstrated the strongest agreement in calibration ability analysis. The easily accessible automated web-based scoring risk-stratification system may overcome the complexity of the various Thyroid Imaging Reporting and Data System guidelines and provide simplified guidance on personalized and optimal management in real practice.

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.

Detection of Malignancy Among Suspicious Thyroid Nodules <1 cm on Ultrasound with Various Thyroid Image Reporting and Data Systems

BACKGROUND

In patients undergoing active surveillance of papillary thyroid microcarcinoma, definitive therapy-usually preceded by a definitive diagnostic procedure-is not recommended until evidence of disease progression is obtained, as stated in the American Thyroid Association guidelines. This is because the deferring of definitive diagnosis and therapy until disease progression has no impact on the disease-specific survival. This study evaluated the malignancy rate and probability of thyroid nodules, which was further stratified based on the size cutoff value of 1 cm, with suspicious findings on ultrasonography (US), by using various malignant stratification systems.

METHODS

The data were retrospectively collected between January 2003 and June 2003 from nine university hospitals that had previously participated in the Korean Society of Thyroid Radiology multicenter study on the ultrasonographic differentiation between benign and malignant thyroid nodules. In total, 829 thyroid nodules from 711 patients (620 women, 91 men; M_age = 48.7 years; range 6-98 years; 351 malignant and 478 benign nodules) were included. The probability for malignancy of thyroid nodules was calculated, which was further stratified by size, by using four different types of malignant risk-stratification systems. The factors that could differentiate benign from malignant nodules were assessed using the chi-square test.

RESULTS

In the suspicious thyroid nodules <1 cm on US, the malignancy probability ranged from 77.4% to 82.8%; the lowest rate was found in the Korean Society of Thyroid Radiology multicenter study, whereas the highest rate was noted in the Web-based system. Thus, the probability of benign nodules among suspicious thyroid nodules <1 cm on US was 17.2-22.6%.

CONCLUSION

A biopsy should be considered before active surveillance to exclude benign nodules with suspicious US features, and could thus prevent unnecessary active surveillance and patient anxiety.

Ethanol and thermal ablation for malignant thyroid tumours

Papillary thyroid carcinoma (PTC) is the most common subtype of thyroid malignancy and has a good prognosis and low mortality rate. Surgery is the standard treatment for patients with primary and recurrent thyroid cancer. Although patients with PTC usually exhibit excellent treatment outcome, the incidence of recurrence in the neck ranges from 20% to 59%. When a patient with thyroid cancer is contraindicated for surgery, ultrasound (US)-guided ablation techniques, including ethanol ablation (EA) and thermal ablations, are suggested alternatives. In this review, we evaluated the indications, devices, techniques, clinical outcomes, and complications associated with US-guided EA and thermal ablations based on available scientific evidence and expert opinions regarding the use of ablation for primary and recurrent thyroid cancers.

Radiofrequency ablation of small follicular neoplasms: initial clinical outcomes

BACKGROUND

In thyroid gland, radiofrequency ablation (RFA) has been applied to both recurrent cancers and benign nodules, although, according to the American Thyroid Association (ATA) and the Korean Society of Thyroid Radiology (KSThR) guidelines, surgery is the first-line treatment for follicular neoplasm. However, it has been argued that follicular neoplasm with lower risk of malignancy can be managed by close follow-up. In this study, we evaluated the effectiveness of RFA of small follicular neoplasms, examining reductions in volume and related clinical problems, and making observations over long-term follow-up.

METHODS

We evaluated 10 follicular neoplasms in 10 patients who were treated with RF ablation between 2009 and 2011. A RF generator and an 18-gauge internally cooled electrode were used to perform complete ablation of the whole nodules. Changes in nodules or ablated zones on follow-up ultrasound, and complications during and after RF ablation were evaluated.

RESULTS

The mean follow-up period was 66.4 ± 5.1 months (range: 60-76 months). In eight patients, single session of RF ablation was sufficient, while two patients required two sessions. There was a significant reduction in the mean volume (99.5 ± 1.0%) of lesions, with eight ablated lesions (8/10, 80%) disappearing completely on follow-up. No recurrences were found in any ablated zones at last follow-up. Transient mild neck pain (n = 6) occurred during the procedure without requiring any medication.

CONCLUSION

In addition to active surveillance, RF ablation may be an effective and safe alternative for the management of patients with small (<2 cm) follicular neoplasm suspected on thyroid biopsy and who strongly refuse surgery.

Deaths related to differentiated thyroid cancer: a rare but real event

Objective

The present study describes the clinical and tumor characteristics of patients that died from differentiated thyroid cancer and reports on the cause and circumstances of death in these cases.

Subjects and methods

Retrospective analysis of all the differentiated thyroid cancer (DTC) related deaths at a single institution over a 5-year period, with a total of 33 patients.

Results

Most of the patients were female (63.6%), with a mean age at diagnosis of 58.2 years. The most common histologic type was papillary (66.7%) and 30.3% were follicular. The distribution according to the TNM classification was: 15.4% of T1; 7.7% T2; 38.4% T3; 19.2% of T4a and 19.2% of T4b. Forty-four percent of cases were N0; 20% N1a and 36.6% of N1b. Twelve patients were considered non-responsive to radioiodine. Only one of the patients did not have distant metastases. The most common metastatic site was the lung in 69.7%. The majority of deaths were due to pulmonary complications related to lung metastases (17 patients, 51.5%), followed by post-operative complications in 5 cases, neurological disease progression in 3 cases, local invasion and airway obstruction in one patient. Median survival between diagnosis and death was reached in 49 months while between disease progression and death it was at 22 months.

Conclusion

Mortality from DTC is extremely rare but persists, and the main causes of death derive from distant metastasis, especially respiratory failure due to lung metastasis. Once disease progression is established, median survival was only 22 months.

False-positive cytopathology results for papillary thyroid carcinoma: A trap for thyroid surgeons

OBJECTIVES

Current preoperative diagnosis of thyroid nodules remains imperfect despite recent advances in cytopathology and molecular diagnostics. False positivity in preoperative fine-needle aspiration cytology (FNAC) may lead to overtreatment of patients, including total thyroidectomy, and sometimes to lawsuits for misdiagnosis and malpractice. In this study, we analysed clinical characteristics and pathologic findings in patients with false positivity for papillary thyroid carcinoma (PTC) in FNAC.

METHODS

We retrospectively reviewed permanent pathology results from 3788 patients who underwent thyroid surgery. Among them, 48 patients had lesions that were deemed suspicious or positive (Bethesda class V or VI) for PTC in preoperative FNAC. We reviewed clinic-pathologic data, radiologic findings and surgical planning in these patients.

RESULTS

The prevalence of pathologic thyroiditis was significantly higher among patients with false-positive FNAC results than in those with confirmed PTC (54.2% vs 9.2%, P<.001). The analysis of the permanent pathology reports showed that 26 patients had chronic lymphocytic thyroiditis and 22 patients had no evidence of thyroiditis. Among the patients without pathologic thyroiditis, 19 patients (86.4%) had nodular hyperplasia and three (13.6%) had follicular adenoma, while among the patients with pathologic thyroiditis, seven (26.9%) had no nodule, 14 (53.8%) had nodular hyperplasia, two (7.7%) had hyalinized nodules, two (7.7%) had follicular adenoma and one (3.8%) had a hyalinizing trabecular tumour. In 42 patients, the extent of surgery (total thyroidectomy or hemithyroidectomy) was to be determined according to the intra-operative frozen section biopsy results. Among them, four (10.5%) had inconclusive frozen section results, and 38 (90.5%) had benign results on frozen section.

CONCLUSIONS

Patient counselling about the possibility of false positivity is still important. And the presence of thyroiditis might create confusion in the interpretation of cytopathologic results.

An online questionnaire survey on preferred timing for the diagnosis and management of thyroid carcinoma in general population in Korea

PURPOSE

An optimal timing for diagnosis and management of papillary thyroid microcarcinoma (PTMC) has become the subject for much controversy. The aim of the present study is to analyze people's preference in Korea for timing of diagnosis and management of PTMC using an online questionnaire.

METHODS

The questionnaire consists of 3 questions about preference for the diagnosis and management of PTMC and 3 additional questions about respondents' personal information. An online survey was conducted from March 3 to June 3 in 2015 using Google Survey (http://goo.gl/forms/b81yEjqNUA).

RESULTS

A total 2,308 persons (1,246 males, 1,053 females) answered the questionnaire. Respondents' ages varied widely from teenagers to 70-year-olds. If there was a suspicious thyroid nodule from PTMC measuring less than 1 cm in diameter, 95.7% of respondents want to know a cytological diagnosis for it. If a thyroid nodule turned out to be a PTMC, 59.5% of respondents wanted it removed immediately. For surgical management of PTMC, 53.0% of respondents were worried more about recurrences than complications. In subgroup analyses, respondents younger than 40 years old more often want immediate surgery than others: 66.7% vs. 32.7% (P < 0.05). Respondents who underwent thyroid cancer surgery (n = 91) were worried more about recurrences than others: 69.2% vs. 52.4% (P < 0.05).

CONCLUSION

Almost all respondents in the present study wanted diagnosis of suspicious thyroid nodules immediately. However, there were opposing opinions about the preferred timing for surgical treatment and surgical extents. A patient's right to know their disease status and decision on treatments should be emphasized all the more.