Active Surveillance for Patients With Papillary Thyroid Microcarcinoma: A Single Center's Experience in Korea

Mortality Risk of Nonoperative Papillary Thyroid Carcinoma: A Corollary for Active Surveillance

Background: Active surveillance is established as an alternative to surgery for papillary thyroid microcarcinomas, but inclusion criteria and mortality risk for pursuing a nonsurgical approach have not been clearly defined. To gauge the feasibility of expanding active surveillance thresholds, we investigated the effects of increasing size and age on disease-specific survival (DSS) in a large nonoperative thyroid cancer cohort, compared against a matched group of surgical patients. Methods: Papillary thyroid carcinoma patients staged T1-4N0M0 were identified in the Surveillance, Epidemiology, and End Results (SEER) database between 1975 and 2015, stratified by nonsurgical and surgical management. Propensity score matching was performed to adjust for imbalances in covariates. Multivariable models were constructed using restricted cubic splines to model nonlinear relationships of age and tumor size with DSS. Results: Overall, 1453 nonoperative patients and 54,718 surgical patients met the inclusion criteria. Collectively, increasing age and size after certain thresholds independently led to greater differences in DSS between nonsurgical and surgical patients. For younger ages (14-55 years), surgical approach compared with nonsurgical approach was not associated with any difference in the 10-year DSS among 0-4 cm cancers (99.8% vs. 100%, p = 0.470), 4.1-6 cm cancers (98.8% vs. 100%, p = 0.599), or >6 cm cancers (97.3% vs. 100%, p = 0.718). Older patients with larger tumors (>75 years, >6 cm) demonstrated the greatest difference in DSS (48.1% vs. 91.3%, p < 0.001). Similar results were found when applying propensity score matching. For age, restricted cubic spline plots showed minimal relative survival hazard in nonoperative cases beginning after age 60 years, with a change point illustrating acceleration in relative hazard beyond age 72 years. For size, relative survival hazard was observed after 2.0 cm and increased slowly with nodule growth up to an inflection point of 4.5 cm. Beyond this, mortality risk escalated with each additional year without plateau. Conclusions: Increasing age and size lead to progressively greater mortality risk without surgery, but only beyond certain thresholds. We define escalating gradients at which a nonsurgical approach may be deemed appropriate, and beyond which survival benefits from surgery become apparent. Such findings reconcile controversial observations regarding age and size in active surveillance and further reshape evolving treatment paradigms in thyroid cancer.

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.

Active surveillance in papillary thyroid carcinoma: not easily accepted but possible in Latin America

OBJECTIVES

To determine the percentage of patients with papillary thyroid carcinoma (PTC) who accepted active surveillance as an alternative to surgery in our clinical practice and to describe the clinical characteristics and outcomes of patients with Bethesda category V and VI thyroid nodules who chose active surveillance.

SUBJECTS AND METHODS

We included 136 PTC patients from the Hospital de Clínicas, University of Buenos Aires without (i) US extrathyroidal extension, (ii) tumors adjacent to the recurrent laryngeal nerve or trachea, and/or (iii) US regional lymph-node metastasis or clinical distant metastasis. PTC progression was defined as the presence of i) a tumor larger than ≥ 3 mm, ii) novel appearance of lymph-node metastasis, and iii) serum thyroglobulin doubling time in less than one year. For patients with these features, surgery was recommended.

RESULTS

Only 34 (25%) of 136 patients eligible for active surveillance accepted this approach, and around 10% of those who accepted abandoned it due to anxiety. The frequency of patients with tumor enlargement was 17% after a median of 4.6 years of follow-up without any evidence of nodal or distant metastases. Ten patients who underwent surgical treatment after a median time of 4 years of active surveillance (AS) had no evidence of disease after a median of 3.8 years of follow-up after surgery.

CONCLUSION

Although not easily accepted in our cohort of patients, AS would be safe and easily applicable in experienced centers.

Thyroid nodules ≤ 1 cm and papillary thyroid microcarcinomas: Brazilian experts opinion

The indolent evolution of low-risk papillary thyroid microcarcinoma (mPTC) in adult patients and the consequences of thyroidectomy require a revision of the management traditionally recommended. Aiming to spare patients unnecessary procedures and therapies and to optimize the health system in Brazil, we suggest some measures. Fine-needle aspiration of nodules ≤ 1 cm without extrathyroidal extension on ultrasonography should be performed only in nodules classified as "very suspicious" (i.e., high suspicion according to ATA, high risk according to AACE, TI-RADS 5) and in selected cases [age < 40 years, nodule adjacent to the trachea or recurrent laryngeal nerve (RLN), multiple suspicious nodules, presence of hypercalcitoninemia or suspicious lymph nodes]. Active surveillance (AS) rather than immediate surgery should be considered in adult patients with low-risk mPTC. Lobectomy is the best option in patients with unifocal low-risk mPTC who are not candidates for AS because of age, proximity of the tumor to the trachea or RLN, or because they opted for surgery. The same applies to patients who started AS but had a subsequent surgical indication not due to a suspicion of tumor extension beyond the gland or multicentricity. Molecular tests are not necessary to choose between AS and surgery or, in the latter case, between lobectomy and total thyroidectomy. The presence of RAS or other RAS-like mutations or BRAFV600E or other BRAF V600E-like mutations should not modify the management cited above; however, the rare cases of mPTC exhibiting high-risk mutations, like in the TERT promoter or p53, are not candidates for AS.

Risk Stratification in Differentiated Thyroid Cancer: From Detection to Final Follow-Up

CONTEXT

Modern management of differentiated thyroid cancer requires individualized care plans that tailor the intensity of therapy and follow-up to the estimated risks of recurrence and disease-specific mortality.

DESIGN

This summary is based on the authors' knowledge and extensive clinical experience, supplemented by review of published review articles, thyroid cancer management guidelines, published staging systems, and original articles identified through a PubMed search, which included terms such as risk stratification, staging, clinical outcomes, and differentiated thyroid cancer.

MAIN OUTCOME MEASURES

In the past, risk stratification in differentiated thyroid cancer usually referred to a static estimate of disease-specific mortality that was based on a small set of clinicopathological features available within a few weeks of completing initial therapy (thyroidectomy, with or without radioactive iodine). Today, risk stratification is a dynamic, active process used to predict the appropriateness for minimalistic initial therapy, disease-specific mortality, risk of recurrence, and the most likely response to initial therapy. Rather than being a static prediction available only after initial therapy, modern risk stratification is a dynamic, iterative process that begins as soon as a suspicious nodule is detected and continues through final follow-up.

CONCLUSIONS

Dynamic risk assessment should be used to guide all aspects of thyroid cancer management, beginning before a definitive diagnosis is made and continuing through the final follow-up visit.

Quality of Life in Patients with Papillary Thyroid Microcarcinoma Managed by Active Surveillance or Lobectomy: A Cross-Sectional Study

Background: Active surveillance (AS) is recommended as an alternative to immediate surgery in patients with papillary thyroid microcarcinoma (PTMC), but the impact of AS on quality of life has not been reported. The aim of this study was to compare quality-of-life parameters in patients with PTMC under AS versus those who underwent lobectomy (LB). Methods: In this cross-sectional study, patients with PTMC were prospectively enrolled between June 2016 and October 2017. All patients completed three questionnaires: the 12-item short-form health survey, thyroid cancer-specific quality of life, and fear of progression. The results were compared after adjusting for age, sex, and serum thyrotropin levels. Results: The AS group comprised 43 patients, and the LB group comprised 148 patients. According to the 12-item short-form health survey questionnaire, the score for role limitations due to emotional problems showed a significant negative association between the groups (coefficient [coef]: -7.71 [confidence interval (CI) -15.26 to -0.16], p = 0.045). The thyroid cancer-specific quality of life questionnaire also showed statistically significant differences between the groups with respect to three scores: neuromuscular problems (coef: 4.99 [CI 0.63-10.62], p = 0.020), throat/mouth problems (coef: 5.28 [CI 0.18-10.38], p = 0.043), and scar problems (coef: 9.34 [CI 4.38-14.29], p < 0.001), suggesting a higher level of complaint in the LB group than in the AS group. No significant differences in fear of progression scores were seen between the two groups. Conclusions: Patients with PTMC underwent LB experienced more health-related problems than those managed by AS. These findings support the role of AS as a reasonable management option for patients with PTMC.

Comparison of Natural Course between Thyroid Cancer Nodules and Thyroid Benign Nodules

BACKGROUND

The natural course of thyroid cancer nodules and benign nodules is different. This study was to compare the changes in size between thyroid cancer nodules and thyroid benign nodules. The risk factors associated with the changes of thyroid cancer nodules were assessed.

METHODS

This study contains retrospective observational and prospective analysis. A total of 113 patients with 120 nodules were recruited in the cancer group, and 116 patients with 119 nodules were enrolled in the benign group. Thyroid ultrasonography was performed at least two times at more than 1-year interval.

RESULTS

The mean follow-up durations were 29.5±18.8 months (cancer group) and 31.9±15.8 months (benign group) (P=0.32). The maximum diameter change in length was 0.36±0.97 mm/year in the cancer group and -0.04±0.77 mm/year in the benign group (P<0.01). The volume was significantly increased in the cancer group compared with the benign group (0.06±0.18 mL/year vs. 0.004±0.05 mL/year, respectively, P<0.01; 26.9%±57.9%/year vs. 1.7%±26.0%/year, P<0.01). Initial maximum diameter (β=0.02, P<0.01) and initial volume (β=0.13, P<0.01) were significantly associated with volume change (mL)/year. Initial maximum standardized uptake value did not predict the nodule growth.

CONCLUSION

It is suggested that thyroid cancer nodules progress rapidly compared with benign nodules. Initial size and volume of nodule were independent risk factors for cancer nodule growth.

Tumor Volume Doubling Time in Active Surveillance of Papillary Thyroid Carcinoma

Background: Tumor volume (TV) of papillary thyroid carcinoma (PTC) increases exponentially during active surveillance, and the growth rate differs for each patient. TV doubling time (TVDT) is considered a strong dynamic marker for the prediction of the growth rate and progression of the tumor. Methods: This cohort study analyzed 273 PTC patients who underwent active surveillance for more than one year rather than immediate thyroid surgery. TVDT was calculated in each patient, and patients were divided into two groups: rapid-growing (TVDT <5 years) and stable (TVDT ≥5 years). Clinical and initial ultrasonography (US) features between the two groups were compared. Results: The median patient age was 51.1 years (interquartile range [IQR] 42.2-61.0 years), and 76% of the patients were women. The initial TV of PTC was 62.1 mm³ (IQR 28.1-122.8 mm³). During a median of 42 months (IQR 29-61 months) of active surveillance, 10.3% of the patients had a TVDT of less than two years, 5.1% had a TVDT between two and three years, 6.2% had a TVDT between three and four years, 6.6% had a TVDT between four and five years, and 71.8% had a TVDT of five years or more. Patients in the rapid-growing group (77 patients; 28.2%) were significantly younger (p = 0.004) than those in the stable group (196 patients; 71.8%). Being younger than 50 years of age was significantly associated with rapid tumor growth of PTC (odds ratio = 2.31 [confidence interval 1.30-4.31], p = 0.004) in multivariate analysis. In ultrasound findings, macrocalcification was independently associated with rapid tumor growing of PTCs (odds ratio = 4.98 [confidence interval 2.19-11.69], p < 0.001). Conclusions: TVDT is a good indicator for presenting the growing velocity of PTCs during active surveillance. Younger age and macrocalcification in the initial US were associated with rapid-growing PTCs. Determination of TVDT during the early phase of active surveillance may be helpful for the prediction of rapidly progressing PTCs and deciding whether to adopt an early surgical approach.

Mutational profile of papillary thyroid microcarcinoma with extensive lymph node metastasis

PURPOSE

Papillary thyroid microcarcinoma (PTMC) has excellent outcomes, but extensive lymph node (LN) metastasis can be associated with fatal outcomes. We evaluated the mutational profiles of primary tumors and their metastatic LNs of PTMCs with extensive lateral cervical LN metastases.

METHODS

Formalin-fixed, paraffin-embedded archival samples from 16 sets of normal thyroid tissue, the primary PTMC, and the largest metastatic LN were used for targeted sequencing.

RESULTS

A total of seven somatic variants were confirmed in the PTMCs compared to the normal tissue. The BRAF^V600E mutation was the most common and seen in 12 primary tumors (75%) and 11 metastatic LNs (69%). A nonsense mutation in AR and an in-frame deletion in ACVR2A were detected in one primary tumor and its metastatic LN (6%). Missense mutations in KMT2A, RAF1, and ROS1 were detected in one primary tumor (3%). A frameshift deletion mutation in JAK2 was detected in a metastatic LN (3%). In PTMCs without the BRAF mutation, an ALK and RET rearrangement (one PTMC and its metastatic LN, 6%) was detected. In one patient, the BRAF mutation was detected in the primary tumor, but only a RET rearrangement was detected in its metastatic LN. No mutations were detected in two patients.

CONCLUSION

The mutational frequency of PTMCs was really low, even in those with extensive LN metastasis. The mutational status of the primary tumor and its metastatic LNs were not significantly different, and this suggests a minor role for genetic alterations in the process of LN metastasis in PTMC.

Papillary microcarcinoma of the thyroid gland: current controversies and management

PURPOSE OF REVIEW

To highlight recent advances in our understanding of the nature of micropapillary thyroid carcinoma (mPTC), its evaluation and options of management based on risk.

RECENT FINDINGS

A dramatic increase of the incidence of papillary thyroid carcinoma has been reported worldwide during recent decades, specifically those smaller than 10 mm (mPTC). Although not taking into consideration other risk factors for aggressiveness when describing tumours by their size, most of these newly diagnosed mPTC are indolent and active surveillance can be considered as valid option for their management.

SUMMARY

An increasing number of patients with mPTC will be encountered in clinical practice. Although it is difficult to assess the aggressiveness of a tumour on size criteria, less than a total thyroidectomy and active surveillance can be considered for the majority of patients with mPTC. Further trials should be performed to prove this as a valid option of management in the majority of these patients.

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.

Active Surveillance for T1bN0M0 Papillary Thyroid Carcinoma

BACKGROUND

Prospective trials of active surveillance for asymptomatic papillary microcarcinoma (T1aN0M0) since the 1990s have shown progression rates of only 5-10%. Late rescue surgery after progression had no deleterious effects on mortality and morbidity. The 2015 American Thyroid Association guidelines approved active surveillance for very low-risk papillary thyroid carcinoma (PTC) as an alternative method to immediate surgery. However, there is no study that evaluates long-term active surveillance for T1b tumors.

METHODS

A prospective trial of active surveillance with 360 very low-risk PTC (T1aN0M0) patients has been conducted since 1995. Of the 392 T1bN0M0 patients, 61 selected active surveillance over surgery and eventually participated in this trial, while the remaining 331 patients underwent surgery. To find an appropriate management strategy for patients with T1bN0M0 PTC, the outcomes of active surveillance for T1bN0M0 to T1aN0M0 PTC were investigated and compared, and the outcomes of surgery for T1bN0M0 PTC were studied.

RESULTS

After a mean of 7.4 years of active surveillance, 29 (8%) T1aN0M0 tumors and four (7%) T1bN0M0 tumors had increased in size (p = 0.69). Development of lymph node metastasis was seen in three (0.8%) patients and two (3%) patients, respectively (p = 0.10). No significant difference in progression rate was seen between groups. Among T1bN0M0 tumors, weak calcification and rich vascularity were risk factors for tumor-size increase, and younger age was a predictor for the development of lymph node metastasis. Mean initial tumor size was significantly greater in T1bN0M0 patients who underwent immediate surgery (14.5 ± 2.8 mm) than it was in patients who chose observation (11.7 ± 1.1 mm; p < 0.0001). No postoperative recurrence was seen in patients with tumor <15 mm in diameter.

CONCLUSIONS

Active surveillance is an option for selected patients with T1bN0M0 PTC.

Differentiated Thyroid Cancer, From Active Surveillance to Advanced Therapy: Toward a Personalized Medicine

Differentiated thyroid cancer (DTC) is the most frequent endocrine malignancy and represents the most rapidly increasing cancer diagnosis worldwide. In the last 20 years, this increase has been mostly due to a higher detection of small papillary thyroid cancers, with doubtful effects on patients' outcome. In fact, despite this growth, cancer-related death remained stable over the years. The growing detection of microcarcinomas associated to the indolent behavior of these cancers led to the development of strategies of active surveillance in selected centers of different countries. Moreover, toward a more personalized approach in the management of DTC patients, surgical treatments became more conservative, favoring less extensive options in patients at low risk of recurrence. The rise in lobectomy in low-risk cases and the need to avoid further therapies, with controversial impact on recurrences and cancer-related death in selected intermediate risk cases, led to reconsider the use of radioiodine treatment, too. Since clinicians aim to treat different patients with different modalities, the cornerstone of DTC follow-up (i.e., thyroglobulin, thyroglobulin autoantibodies, and neck ultrasound) should be interpreted consistently with this change of paradigm. The introduction of novel molecular target therapies (i.e., tyrosine kinase inhibitors), as well as a better understanding of the mechanisms of immune checkpoint inhibitor therapies, is radically changing the management of patients with advanced DTC, in whom no treatment option was available. The aim of this review is to analyze the most recent developments of the management of DTC, focusing on several key issues: active surveillance strategies, initial treatment, dynamic risk re-stratification, and therapeutic options in advanced DTC.

Surgical Treatment in Papillary Thyroid Microcarcinoma

Despite the notable increasing incidence of papillary thyroid microcarcinoma (PTMC), the optimal treatment of the patients with PTMC remains controversial. Because of no consensus about its treatment, the suggested treatment varies from active surveillance alone to total thyroidectomy. Although the 2015 revised American Thyroid Association guideline recommends hemithyroidectomy as the first-line treatment, active surveillance has also been discussed and accepted as another approach for the patients with PTMC. However, the same guideline does not recommend fine needle aspiration biopsy for nodules sized <1 cm, even it is suspicious. In such situation, neither active surveillance nor hemithyroidectomy could be discussed, with a lack of objective cytologic data about the nodules sized <1 cm. In this situation, the decision to perform FNAB to the nodules <1 cm in size depends on the performer of the thyroid ultrasonography. In this invited review, we have discussed the diagnosis and prognostic factors for PTMCs. We have also discussed surgical strategies as the accepted the first-line treatment in patients with PTMC.

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.

Active Surveillance of Low-Risk Papillary Thyroid Microcarcinoma: A Multi-Center Cohort Study in Korea

BACKGROUND

Active surveillance has been introduced as a management option for low-risk papillary thyroid microcarcinoma (PTMC) due to its mostly indolent course.

METHODS

This was a multicenter study of 370 PTMC patients who underwent active surveillance more than one year. The changes in volume and maximum diameter between initial and last ultrasonography were evaluated to identify the natural course of PTMC during active surveillance.

RESULTS

Patients' age at diagnosis was 51 ± 12 years, and 110 (30%) patients were <45 years of age. The initial maximum diameter and volume of PTMCs were 5.9 ± 1.7 mm and 81.0 ± 77.7 mm³, respectively. During the median 32.5 months of follow-up, 86 (23.2%) patients were found to have an increase in tumor volume, and 13 (3.5%) patients showed an increase in the maximal diameter of the tumor. The cumulative incidence of volume increase gradually rose with time (6.9%, 17.3%, 28.2%, and 36.2% after two, three, four, and five years, respectively). The risk of volume increase in patients <45 years of age was twice as high as in older patients (p = 0.002). There was no significant difference in tumor size change according to sex, levothyroxine treatment, or presence of Hashimoto's thyroiditis. During the period, 58 (15.7%) patients underwent delayed thyroid surgery due to anxiety (37.9%), tumor size increase (32.8%), or appearance of cervical lymph node metastasis (8.6%). Lymph node metastasis was found in 29.3% of patients on pathological examination.

CONCLUSIONS

A significant number of PTMCs grow during active surveillance, and tumor volume change is a more sensitive means of evaluating tumor growth. Active surveillance can be carefully applied for selected patients. Although it is not contraindicated, it should be applied more cautiously for younger patients.

Thyroid Cancer Treatment Choice: A Pilot Study of a Tool to Facilitate Conversations with Patients with Papillary Microcarcinomas Considering Treatment Options

BACKGROUND

The 2015 American Thyroid Association guidelines recognize active surveillance as an alternative to immediate surgery in patients with papillary microcarcinomas (PMCs). As a way to incorporate active surveillance as one of the management options for patients with PMCs, we developed and tested a tool to support conversations between clinicians and patients with PMCs considering treatment options.

METHODS

Thyroid Cancer Treatment Choice was developed using an iterative process based on the principles of interaction, design, and participatory action research. To evaluate the impact of the tool on treatment choice, a prospective study was conducted in two thyroid cancer clinics in Seongnam-si and Seoul, South Korea. Both clinics had the expertise to offer active surveillance as well as immediate surgery. One clinic was trained in the use of the conversation aid, while the other clinic continued to care for patients without access to the conversation aid.

RESULTS

Between May 2016 and April 2017, 278 patients, mostly women (n = 220, 79%), were included in the study; 152 (53%) received care at the clinic using the conversation aid. Age, sex, and mean (±SD) tumor size (6.6 ± 1.6 mm and 6.5 ± 1.9 mm) distributions were similar across clinics. Overall, 233 (84%) patients opted for active surveillance and 53 (16%) for thyroid surgery. Patients in the conversation aid group were more likely to choose active surveillance than the patients seen in the usual care clinic (relative risk = 1.16 [confidence interval 1.04-1.29]). Of all patients opting for active surveillance, more patients in the conversation aid group had thyroid cancer nodules >5 mm than in the usual care group (81% vs. 67%; p = 0.013).

CONCLUSIONS

Thyroid Cancer Treatment Choice is an evidence-based tool that supports the presentation of treatment options for PMCs. Pilot testing suggests that this conversation tool increases acceptance of active surveillance, suggesting that this option is an acceptable and preferable alternative for informed patients. Further studies are warranted to confirm this finding.

Evolving management considerations in active surveillance for micropapillary thyroid carcinoma

PURPOSE OF REVIEW

To summarize developments on active surveillance for micropapillary thyroid cancers, with a focus on strategies for optimal risk stratification and caveats that currently limit adoption.

RECENT FINDINGS

Observational trials encompassing thousands of active surveillance patients worldwide have increasingly demonstrated the viability of active surveillance for small, low-risk thyroid cancers. Collectively, these data have established that with proper patient selection and strict monitoring, more than 85% of such cases remain indolent no meaningful clinical growth over at least 10 years. Moreover, to date no cases of symptomatic progression or distant metastasis have been reported, and that delayed treatment when needed has not led to unresectable disease or higher risk of complications. Deeper investigation to better predict clinical progression is necessary to improve patient selection, given concerns regarding patient anxiety, age eligibility, and underestimation of true disease extent.

SUMMARY

Compelling data from ongoing trials support active surveillance as a first-line management option for micropapillary thyroid carcinomas. Proper risk stratification and strict monitoring protocols will be necessary to sustain the excellent results achieved to date. Broad adoption of active surveillance will require further education, collaboration, and equipoise between physicians and patients to optimize such individualized treatment plans.

Are Papillary Thyroid Carcinomas That Are Candidates for Active Surveillance in Fact Classical Microcarcinomas Restricted to the Gland?

BACKGROUND

Patients with small papillary thyroid carcinomas (PTC) can currently be maintained under active surveillance (AS). The recommended criteria are the following: adult individual, tumor ≤1 cm and not adjacent to the trachea or recurrent laryngeal nerve, cytology non-suggestive of the aggressive subtype, absence of lymph node (LN) involvement and extrathyroidal extension (ETE) on ultrasonography (US), and absence of clinical distant metastases. This study aimed to evaluate the frequency of the following peri- and postoperative findings in patients who met the criteria for PTC being candidate for AS: tumor > 1 cm, aggressive subtype or vascular invasion, ETE, clinical LN metastases (cN1), and distant metastases.

METHODS

We reviewed the results of peri- and postoperative evaluation and histology of patients with a preoperative diagnosis of PTC who would currently be candidates for AS.

RESULTS

There were 124 patients (102 women) with nodules ≤1 cm (range 4-10 mm). All nodules corresponded to papillary microcarcinomas on histology and none of them were > 1 cm. Only one microcarcinoma (0.8%) was of the tall-cell subtype. Vascular invasion was found in 10 microcarcinomas (8%). None of the microcarcinomas were staged as T3b or T4, although microscopic ETE was observed in 25 tumors (20%). In 8 patients (6.4%), central LN involvement was suspected during perioperative evaluation and was confirmed by histology (cN1a). None of the patients had distant metastases (M0).

CONCLUSION

Findings that define an intermediate risk of recurrence and favor total thyroidectomy were observed in 31.5% of patients with PTC who are candidates for AS.

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.

Long-term oncologic outcomes of papillary thyroid microcarcinoma according to the presence of clinically apparent lymph node metastasis: a large retrospective analysis of 5,348 patients

Purpose

Active surveillance (AS) of low-risk papillary thyroid microcarcinoma (PTMC) may reduce the risk of overtreatment of clinically insignificant cancer. However, the absence of predictor for the progression of PTMC resulted in treatment delay and potentially compromising cure of aggressive disease. Therefore, to anticipate potential damage of delayed surgery, we investigated the oncologic outcomes of patients with low-risk PTMC initially eligible for AS except clinically apparent lymph node metastasis (LNM), imitating delayed surgery with neck dissection.

Materials and methods

A total of 5,348 patients, enrolled between 1987 and 2016, with low-risk PTMC initially eligible for AS were included regardless of LNM. We classified our study patients into two groups: Group I, lobectomy with prophylactic central cervical node dissection; Group II, total thyroidectomy with modified radical neck dissection for LNM. In addition, we investigated the oncological outcomes of patients with second-wave surgery due to lateral lymph node recurrence (Group III, subgroup of Group I).

Results

Group I showed more favorable clinicopathological characteristics compared with Group II. In Group I, only 29 (0.58%) of 4,927 patients underwent second-wave surgery with neck dissection for lateral lymph node recurrences, whereas in Group II, all 22 (5.23%) of 421 patients underwent second-wave selective node dissection because of nodal recurrence. Disease-free survival rates were significantly different between Groups I and II (P<0.05). Of note, the recurrence rate of Group II was still significantly higher than that of Group III (5.2% vs 0%, respectively; P=0.021). In addition, Kaplan–Mayer survival analysis indicated poor disease-free survival rates in Group II compared with Group III (P<0.05).

Conclusion

The long-term treatment outcome of PTMC without LNM was favorable even if the recurrence occurs during follow-up period compared with that of PTMC with LNM. It should be noted that AS might be able to cause poor prognosis due to clinically apparent LNM.

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.

Is biopsy enough for papillary thyroid microcarcinoma?: An analysis of the SEER database 2004 to 2013 with propensity score matching

The treatment of papillary thyroid microcarcinoma (PTMC) remains deeply controversial. In this study, we investigated the prognosis of patients who underwent biopsy alone, as compared with other forms of thyroidectomy approaches. We sought to provide reference information for treatment selection in cases of PTMC.The analysis included a large cohort of 34,972 PTMC patients from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2013. Survival was examined by Kaplan-Meier analyses with log-rank tests, Cox proportional-hazards regression analyses, and propensity score matching analyses.In the study cohort, the rate of cancer-specific mortality per 1000 person-years was higher for patients who underwent biopsy alone than for those who underwent other surgical approaches. According to multivariate Cox regression analyses, patients undergoing biopsy had similar cancer-specific survival rates and higher all-cause survival rates in comparison with patients undergoing other surgical approaches. After matching for influential factors using propensity scores, Kaplan-Meier analyses also showed that patients undergoing biopsy had similar cancer-specific survival rates and lower all-cause survival rates in comparison with patients undergoing other surgical approaches.Our results provided helpful implications for the treatment of patients with PTMC.

How to handle borderline/precursor thyroid tumors in management of patients with thyroid nodules

Thyroid carcinomas originating from follicular cells have the prognosis of heterogeneous diseases, but pathologists classify them all as malignant disease. Epidemiologists have issued a stern warning regarding over-diagnosis and overtreatment of patients with indolent thyroid tumors that cause no harm to the patients. Review of the literature revealed that there were several proposals of borderline/precursor tumors to some indolent thyroid carcinomas. Thyroid tumor of uncertain malignant potential (UMP) was first proposed by Williams for encapsulated follicular pattern thyroid tumors to solve problems due to observer variation. Rosai et al. proposed to rename papillary microcarcinoma (PMC) to papillary micro-tumor as the overwhelming majority of them are of no clinical significance. Liu et al. proposed well-differentiated tumor with uncertain behavior (WDT-UB) which covered WDT of UMP (WDT-UMP) and non-invasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC). The EFVPTC without invasion was renamed as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) by an international panel of pathologists. A new prognostic classification of thyroid tumors was proposed by Kakudo et al., in which extremely low risk tumors were grouped in a borderline tumors category. The borderline/precursor thyroid tumors included encapsulated tumors [capsular invasion only follicular carcinoma, encapsulated papillary carcinoma without invasion, WDT-UMP and follicular tumor of UMP (FT-UMP)] and non-encapsulated tumors (PMC). The UMP and NIFTP were incorporated in the 4th edition WHO classification of thyroid tumors as a new tumor entity in chapter 2-2A: other encapsulated follicular patterned thyroid tumors. Their behavior codes were decided to be 1 (borderline or uncertain behavior), and not 0 (benign), 2 (in situ carcinoma) or 3 (malignant). These borderline/precursor thyroid tumors are indolent tumors biologically and should be treated more conservatively than as previously recommended for thyroid follicular cell carcinomas [total thyroidectomy (TTX) followed by radio-active iodine (RAI) treatment] by western clinical guidelines.

Ultrasound-guided percutaneous microwave ablation versus surgery for papillary thyroid microcarcinoma

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) has high incidence and low disease-specific mortality. However, active surveillance is not accepted by most patients owing to high physical or psychological pressures. The emergence of ablation technologies is supplanting traditional surgery. Our goal was to compare the clinical outcomes of microwave ablation (MWA) and surgery for T1aN0M0 PTMC.

METHODS

A total of 92 consecutive patients with T1aN0M0 PTMC were studied retrospectively. Forty-six patients had been treated with MWA, and the other 46 had undergone surgery. MWA was performed using extensive ablation extending from the nodule's lower pole to the upper pole. Surgery was performed by total thyroidectomy or thyroid lobectomy. We compared the two groups in terms of mean length of stay, cost, mean blood loss, surgical incision, operating room (OR) time, quality of life (QOL) assessment, complications, and therapeutic efficacy over a follow-up period of 42 months.

RESULTS

The mean length of stay, cost, mean blood loss, surgical incisions, OR time, and complications in the MWA group were significantly lower than those of the surgery group. The QOL after MWA was higher than it was after surgery. The nodule volume decreased significantly from 53.61 ± 48.43 mm³ to 4.84 ± 6.55 mm³ (p < .001) at the 42-month follow-up, exhibiting a percentage volume reduction of 81.33 ± 36.87%. No recurrence or metastasis occurred in either group during the follow-up period.

CONCLUSIONS

MWA may be considered a minimally invasive alternative to surgery for solitary T1aN0M0 PTMC with low incidence of complications and good therapeutic effect.

A clinical framework to facilitate selection of patients with differentiated thyroid cancer for active surveillance or less aggressive initial surgical management

INTRODUCTION

In the past, total thyroidectomy was usually recommended as the initial therapeutic approach in all but the lowest risk differentiated thyroid cancers. Today, many patients with low risk papillary thyroid cancers may be candidates for either an observational management approach (active surveillance/deferred surgical intervention) or a minimalist surgical approach (thyroid lobectomy/isthmusectomy).

AREAS COVERED

After a comprehensive review of the PubMed database and based on our clinical experience, we describe a clinical framework that integrates important factors in three major inter-related domains (pre-operative imaging/clinical findings, medical team characteristics, and patient characteristics) to classify a patient as either ideal, appropriate or inappropriate for conservative treatment options. As part of this clinical framework, we examine how the medical decision making construct (minimalist versus maximalist) of the patient and clinician can impact selection of initial therapy.

EXPERT COMMENTARY

The dramatic rise in the incidence of very low risk differentiated thyroid cancer demands a re-evaluation of the appropriate use of more minimalistic treatment options. The selection of appropriate patients for less aggressive initial treatment options requires thoughtful, open discussions that can be aided by clinical decision making frameworks that recognize and value the medical decision making process of clinicians and patients.

High Serum TSH Level Is Associated With Progression of Papillary Thyroid Microcarcinoma During Active Surveillance

OBJECTIVE

Thyroid-stimulating hormone (TSH) is a growth factor affecting initiation or progression of papillary thyroid cancer (PTC), which supports TSH suppressive therapy in patients with PTC. In patients with papillary thyroid microcarcinoma (PTMC) during active surveillance, however, the association between serum TSH level and growth of PTMC has not been demonstrated.

PATIENTS

We analyzed 127 PTMCs in 126 patients under active surveillance with serial serum TSH measurement and ultrasonography.

DESIGN

The patients were categorized into groups with the highest, middle, and lowest time-weighted average of TSH (TW-TSH). PTMC progression was defined as a volume increase of ≥50% compared with baseline. Kaplan-Meier survival analysis according to TW-TSH groups and Cox proportional hazard modeling was performed. We identified the cutoff point for TSH level by using maximally selected log-rank statistics.

RESULTS

During a median follow-up of 26 months, PTMC progression was detected in 28 (19.8%) patients. Compared with the lowest TW-TSH group, the adjusted hazard ratio (HR) for PTMC progression in the highest TW-TSH group was significantly higher [HR 3.55; 95% confidence interval (CI), 1.22 to 10.28; P = 0.020], but that in the middle TW-TSH group was not (HR 1.52; 95% CI, 0.46 to 5.08; P = 0.489). The cutoff point for the serum TSH level for PTMC progression was 2.50 mU/L.

CONCLUSIONS

Sustained elevation of serum TSH levels during active surveillance is associated with PTMC progression. Maintaining a low-normal TSH range with levothyroxine treatment during active surveillance of PTMC might be considered in future studies.

[Surgery of papillary thyroid microcarcinoma]

BACKGROUND

Different countries are currently reporting a substantial increase in the incidence rates of papillary thyroid microcarcinoma (PTMC).

OBJECTIVE

Presentation of diagnosis and surgical therapy of PTMC and discussion of a more conservative approach, such as active surveillance.

MATERIAL AND METHODS

Overview of the current guidelines from different countries and analysis of recent publications reporting the results of active surveillance of PTMC from Japan, Korea and the USA.

RESULTS

The majority of international guidelines for PTMC recommends thyroid lobectomy as the gold standard. Active surveillance as an alternative procedure is described in the Japanese guidelines (JSTS/JAES). Present surveillance studies including more than 1700 patients report a tumor growth in 8-14% of the cases during a median follow-up of up to 75 months. Tumor growth and lymph node metastases are detected most frequently in younger patients (below 40-50 years).

CONCLUSION

Active surveillance might serve as an alternative treatment option for older patients with PTMC. Since the median follow-up periods are currently not long enough, it seems difficult to draw definite conclusions of this procedure right now.

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.

Young Age and Male Sex Are Predictors of Large-Volume Central Neck Lymph Node Metastasis in Clinical N0 Papillary Thyroid Microcarcinomas

BACKGROUND

Large-volume lymph node metastasis (LNM) is associated with poor clinical outcomes in papillary thyroid microcarcinoma (PTMC) patients. However, sensitivity in the detection of central neck LNM on preoperative neck ultrasonography (US) is believed to be low. The aim of this study is to investigate the preoperative clinical factors associated with large-volume LNM in clinical N0 PTMC patients.

METHODS

In all, 2329 clinical N0 PTMC patients who underwent total thyroidectomy with prophylactic central lymph node (LN) dissection were evaluated. The LNM status of these patients was divided into three groups by the number of metastatic nodes: no LNM, small-volume LNM (≤5 metastatic LNs), and large-volume LNM (>5 metastatic LNs). The correlations between age, sex, and other clinical factors and large-volume LNM were evaluated.

RESULTS

Large-volume LNM was found in 94 (4.0%) patients. Young (<40 years old) and male patients tended to have large-volume LNM (p for trend <0.001). Young age (odds ratio [OR] = 2.69 [confidence interval (CI) 1.64-4.32], p < 0.001) and male sex (OR = 5.79 [CI 3.67-9.10], p < 0.001) were independent risk factors for large-volume LNM in multivariate analyses. The prevalence of large-volume LNM ranged from 24% in male patients <40 years of age to only 2% in female patients aged ≥40 years. Multifocal tumors and presence of extrathyroidal extension were also considered risk factors for large-volume LNM.

CONCLUSIONS

Large-volume LNM was more frequently found in young (<40 years) and male patients. These findings support the notion that surgery rather than observation may be favored in young and male clinically LN negative PTMC patients as a primary therapeutic option.

A new paradigm in low-risk papillary microcarcinoma: active surveillance

Classical papillary thyroid microcarcinoma (PTMC) is a variant of papillary thyroid carcinoma (PTC) known to have excellent prognosis. It has a mortality of 0.3%, even in the presence of distance metastasis. The latest American Thyroid Association guidelines state that although lobectomy is acceptable, active surveillance can be considered in the appropriate setting. We present the case of a 37-year-old female with a history of PTMC who underwent surgical management consisting of a total thyroidectomy. Although she has remained disease-free, her quality of life has been greatly affected by the sequelae of this procedure. This case serves as an excellent example of how first-line surgical treatment may result more harmful than the disease itself.