Study Protocol of Multicenter Prospective Cohort Study of Active Surveillance on Papillary Thyroid Microcarcinoma (MAeSTro)

Ultrasound Imaging in Active Surveillance of Small, Low-Risk Papillary Thyroid Cancer

The recent surge in the incidence of small papillary thyroid cancers (PTCs) has been linked to the widespread use of ultrasonography, thereby prompting concerns regarding overdiagnosis. Active surveillance (AS) has emerged as a less invasive alternative management strategy for low-risk PTCs, especially for PTCs measuring ≤1 cm in maximal diameter. Recent studies report low disease progression rates of low-risk PTCs ≤1 cm under AS. Ongoing research is currently exploring the feasibility of AS for larger PTCs (<20 mm). AS protocols include meticulous ultrasound assessment, emphasis on standardized techniques, and a multidisciplinary approach; they involve monitoring the nodules for size, growth, potential extrathyroidal extension, proximity to the trachea and recurrent laryngeal nerve, and potential cervical nodal metastases. The criteria for progression, often defined as an increase in the maximum diameter of the PTC, warrant a review of precision and ongoing examinations. Challenges exist regarding the reliability of volume measurements for defining PTC disease progression. Although ultrasonography plays a pivotal role, challenges in assessing progression and minor extrathyroidal extension underscore the importance of a multidisciplinary approach in disease management. This comprehensive overview highlights the evolving landscape of AS for PTCs, emphasizing the need for standardized protocols, meticulous assessments, and ongoing research to inform decision-making.

MET-receptor targeted fluorescent imaging and spectroscopy to detect multifocal papillary thyroid cancer

PURPOSE

Multifocal disease in PTC is associated with an increased recurrence rate. Multifocal disease (MD) is underdiagnosed with the current gold standard of pre-operative ultrasound staging. Here, we evaluate the use of EMI-137 targeted molecular fluorescence-guided imaging (MFGI) and spectroscopy as a tool for the intra-operative detection of uni- and multifocal papillary thyroid cancer (PTC) aiming to improve disease staging and treatment selection.

METHODS

A phase-1 study (NCT03470259) with EMI-137 was conducted to evaluate the possibility of detecting PTC using MFGI and quantitative fiber-optic spectroscopy.

RESULTS

Fourteen patients underwent hemi- or total thyroidectomy (TTX) after administration of 0.09 mg/kg (n = 1), 0.13 mg/kg (n = 8), or 0.18 mg/kg (n = 5) EMI-137. Both MFGI and spectroscopy could differentiate PTC from healthy thyroid tissue after administration of EMI-137, which binds selectively to MET in PTC. 0.13 mg/kg was the lowest dosage EMI-137 that allowed for differentiation between PTC and healthy thyroid tissue. The smallest PTC focus detected by MFGI was 1.4 mm. MFGI restaged 80% of patients from unifocal to multifocal PTC compared to ultrasound.

CONCLUSION

EMI-137-guided MFGI and spectroscopy can be used to detect multifocal PTC. This may improve disease staging and treatment selection between hemi- and total thyroidectomy by better differentiation between unifocal and multifocal disease.

TRIAL REGISTRATION

NCT03470259.

Active Surveillance for Low-Risk Thyroid Cancers: A Review of Current Practice Guidelines

The indolent nature and favorable outcomes associated with papillary thyroid microcarcinoma have prompted numerous prospective studies on active surveillance (AS) and its adoption as an alternative to immediate surgery in managing low-risk thyroid cancer. This article reviews the current status of AS, as outlined in various international practice guidelines. AS is typically recommended for tumors that measure 1 cm or less in diameter and do not exhibit aggressive subtypes on cytology, extrathyroidal extension, lymph node metastasis, or distant metastasis. To determine the most appropriate candidates for AS, factors such as tumor size, location, multiplicity, and ultrasound findings are considered, along with patient characteristics like medical condition, age, and family history. Moreover, shared decision-making, which includes patient-reported outcomes such as quality of life and cost-effectiveness, is essential. During AS, patients undergo regular ultrasound examinations to monitor for signs of disease progression, including tumor growth, extrathyroidal extension, or lymph node metastasis. In conclusion, while AS is a feasible and reliable approach for managing lowrisk thyroid cancer, it requires careful patient selection, effective communication for shared decision-making, standardized follow-up protocols, and a clear definition of disease progression.

Surgical Outcomes in Patients With Low-risk Papillary Thyroid Microcarcinoma From MAeSTro Study: Immediate Operation Versus Delayed Operation After Active SurveillanceA Multicenter Prospective Cohort Study

OBJECTIVE

To investigate surgical, and clinical outcomes in patients with low-risk papillary thyroid microcarcinoma (PTMC) according to treatment options [immediate operation (IOP) vs delayed operation after active surveillance (AS) (DOP)].

BACKGROUND

AS has been adopted as an alternative to immediate surgery in patients with low-risk PTMC. Although some patients undergo surgery during AS, there is little information on surgical, and clinical outcomes after delayed operation after AS.

METHODS

A multicenter prospective cohort study including 1177 patients was conducted at 3 tertiary hospitals in Korea from June 2016 to January 2020. Patients with low-risk PTMC were enrolled. The participants were self-assigned into AS or IOP, and during AS, the patients underwent surgery if there were signs of disease progression or if the patient's choice changed.

RESULTS

A total of 516 patients underwent operation; 384 (74.4%) in the IOP group and 132 (25.6%) in the DOP group. Compared with the IOP group, the DOP group was significantly associated with a larger tumor size ( P =0.002), higher rates of lymphatic invasion ( P =0.002), and multifocality ( P =0.008). However, the rates of total thyroidectomy, postoperative hypoparathyroidism and vocal cord palsy did not differ significantly between the groups ( P = 0.283, P =0.184, and P =0.284, respectively). Of the 132 patients in the DOP group, disease progression was present in 39 (29.5%) patients. The DOP group with disease progression had a significantly higher rate of lymph node metastasis ( P =0.021) and radioiodine therapy ( P =0.025) than the DOP group without disease progression.

CONCLUSIONS

These results suggest that AS might be considered an alternative treatment option for patients with low-risk PTMC regarding the extent of thyroidectomy and postoperative complications in the DOP group. To assess oncologic outcomes, long-term follow-up will be needed.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02938702.

US Predictors of Papillary Thyroid Microcarcinoma Progression at Active Surveillance

Background Active surveillance (AS) is an accepted strategy for patients with low-risk papillary thyroid microcarcinoma (PTMC). While previous studies have evaluated the prognostic value of US features, results have been inconsistent. Purpose To determine if US features can help predict tumor progression in patients with low-risk PTMC undergoing AS. Materials and Methods This prospective study enrolled 1177 participants with PTMC from three hospitals between June 2016 and January 2021. Participants were self-assigned to either immediate surgery or AS, and those with two or more US examinations in the absence of surgery were included in the analysis. A χ2 test was used to compare estimated tumor progression rate at 4 years between participants stratified according to US features. Multivariable Cox regression analysis was used to assess the association of clinical and US features with overall tumor progression and specific progression criteria. Results Among 699 participants included in the analysis, 68 (mean age, 49 years ± 12 [SD]; 40 female participants) showed tumor progression (median follow-up, 41.4 months ± 16 [SD]). Tumor progression was associated with the US features of diffuse thyroid disease (DTD) (hazard ratio [HR], 2.3 [95% CI: 1.4, 3.7]; P = .001) and intratumoral vascularity (HR, 1.7 [95% CI: 1.0, 3.0]; P = .04) and the participant characteristics of male sex (HR, 2.8 [95% CI: 1.7, 4.6]; P < .001), age less than 30 years (HR, 2.9 [95% CI: 1.2, 6.8]; P = .01), and thyroid-stimulating hormone level of 7 µU/mL or higher (HR, 6.9 [95% CI: 2.7, 17.4]; P < .001). The risk of tumor progression was higher for participants with DTD (14%, P = .001) or intratumoral vascularity (14%, P = .02) than for participants without these features (6%). DTD and intratumoral vascularity were associated with tumor enlargement (HR, 2.7 [95% CI: 1.4, 5.1]; P = .002) and new lymph node metastasis (HR, 5.0 [95% CI: 1.3, 19.4]; P = .02), respectively. Conclusion DTD and intratumoral vascularity were associated with an increased risk of tumor progression in participants with PTMC undergoing AS. Clinical trial registration no. NCT02938702 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Reuter and the review "International Expert Consensus on US Lexicon for Thyroid Nodules" by Durante et al in this issue.

Lower Thyroid Cancer Mortality in Patients Detected by Screening: A Meta-Analysis

BACKGRUOUND

Thyroid cancer screening has contributed to the skyrocketing prevalence of thyroid cancer. However, the true benefit of thyroid cancer screening is not fully understood. This study aimed to evaluate the impact of screening on the clinical outcomes of thyroid cancer by comparing incidental thyroid cancer (ITC) with non-incidental thyroid cancer (NITC) through a meta-analysis.

METHODS

PubMed and Embase were searched from inception to September 2022. We estimated and compared the prevalence of high-risk features (aggressive histology of thyroid cancer, extrathyroidal extension, metastasis to regional lymph nodes or distant organs, and advanced tumor-node-metastasis [TNM] stage), thyroid cancer-specific death, and recurrence in the ITC and NITC groups. We also calculated pooled risks and 95% confidence intervals (CIs) of the outcomes derived from these two groups.

RESULTS

From 1,078 studies screened, 14 were included. In comparison to NITC, the ITC group had a lower incidence of aggressive histology (odds ratio [OR], 0.46; 95% CI, 0.31 to 0.7), smaller tumors (mean difference, -7.9 mm; 95% CI, -10.2 to -5.6), lymph node metastasis (OR, 0.64; 95% CI, 0.48 to 0.86), and distant metastasis (OR, 0.42; 95% CI, 0.23 to 0.77). The risks of recurrence and thyroid cancer-specific mortality were also lower in the ITC group (OR, 0.42; 95% CI, 0.25 to 0.71 and OR, 0.46; 95% CI, 0.28 to 0.74) than in the NITC group.

CONCLUSION

Our findings provide important evidence of a survival benefit from the early detection of thyroid cancer compared to symptomatic thyroid cancer.

Psychological adjustment to initial treatment for low-risk thyroid cancer: Preliminary study

BACKGROUND

Low-risk papillary thyroid carcinoma (LR-PTC) can be managed by immediate surgery (IS) or active surveillance (AS). We compare the psychological impact of these treatments on patients with LR-PTC.

METHODS

Psychological data were collected over 1 year, with assessments at the time of treatment decision (T1), at 6 months (T2) and 12 months (T3) follow-up. Assessments included 13 validated psychological tools.

RESULTS

Of 27 enrolled patients, 20 chose AS and 7 chose IS. The average times to T2 and T3 were 5.7 and 11.3 months, respectively. For both groups, Impact of Events Scale scores significantly decreased (p = 0.001) at T2, and depressive/anxiety symptoms remained low.

CONCLUSIONS

This study demonstrates the feasibility of assessing psychological outcomes among patients treated for LR-PTC. Further studies are needed to evaluate the impact of AS versus IS on quality of life and changes that patients experience over longer time periods following their treatment decision.

Active Surveillance Versus Immediate Surgery for Low-Risk Papillary Thyroid Microcarcinoma Patients in South Korea: A Cost-Minimization Analysis from the MAeSTro Study

Background: Active surveillance (AS) has been established as an alternative to immediate surgery for low-risk papillary thyroid microcarcinoma (PTMC). Nonetheless, it remains difficult to decide between AS and immediate surgery, since limited objective evidence exists regarding risks and benefits. The aim of study is to compare the cumulative costs of AS and immediate surgery. Methods: To estimate cumulative costs, a hypothetical model is simulated based on the Multicenter Prospective Cohort Study of Active Surveillance on Papillary Thyroid Micro-Carcinoma (MAeSTro) study, a multicenter prospective cohort study of AS for PTMC. Direct and indirect costs are estimated from diagnosis to the treatment decision and follow-up for 10 years and a longer period. In the case of the scenarios, AS, AS to surgery due to changing their mind, and lobectomy (analyzed regardless of levothyroxine [LT4] treatment, as well as subdivided into lobectomy/LT4[-] and lobectomy/LT4[+]) are considered. A sensitivity analysis is performed using different discount rates to address uncertainties in future time costs. To compare the cumulative costs, we referred to previous research conducted in Hong Kong, the United States, and Japan. Results: The initial cost of AS is estimated to be 5.6 times lower than that of lobectomy (regardless of LT4 use), while the 10-year cumulative costs of AS ($2545) and lobectomy regardless of LT4 ($3045) are similar under a discount rate of 3%. However, in the long-term follow-up period, immediate surgery is going to be estimated more economical than AS. The costs of the two management approaches are similar in Hong Kong, but substantially different in the United States and Japan, implying that it could be affected by each country's national health insurance coverage and the thyroid ultrasound interval during follow-up. Conclusion: Considering both direct and indirect costs, the cumulative costs of AS and immediate surgery in low-risk PTMC patients are similar during 10 years, and surgery could be more economical for patients with a life expectancy in long-term follow-up. However, careful interpretation is needed for long-term follow-up and the country's health care system and environment. Nevertheless, considering the representative protocols and objective costs in South Korea, it is expected to be a key to suggest the appropriate treatment for PTMC patients.

Active Surveillance Versus Thyroid Surgery for Differentiated Thyroid Cancer: A Systematic Review

Background: Active surveillance has been proposed as an appropriate management strategy for low-risk differentiated thyroid cancer (DTC), due to the typically favorable prognosis of this condition. This systematic review examines the benefits and harms of active surveillance vs. immediate surgery for DTC, to inform the updated American Thyroid Association guidelines. Methods: A search on Ovid MEDLINE, Embase, and Cochrane Central was conducted in July 2021 for studies on active surveillance vs. immediate surgery. Studies of surgery vs. no surgery for DTC were assessed separately to evaluate relevance to active surveillance. Quality assessment was performed, and evidence was synthesized narratively. Results: Seven studies (five cohort studies [N = 5432] and two cross-sectional studies [N = 538]) of active surveillance vs. immediate surgery, and seven uncontrolled treatment series of active surveillance (N = 1219) were included. One cross-sectional study was rated fair quality, and the remainder were rated poor quality. In patients with low risk (primarily papillary), small (primarily ≤1 cm) DTC, active surveillance, and immediate surgery were associated with similar, low risk of all-cause or cancer-specific mortality, distant metastasis, and recurrence after surgery. Uncontrolled treatment series reported no cases of mortality in low-risk DTC managed with active surveillance. Among patients managed with active surveillance, rates of tumor growth were low; rates of subsequent surgery varied and primarily occurred due to patient preference rather than tumor progression. Four cohort studies (N = 88,654) found that surgery associated with improved all-cause or thyroid cancer mortality compared with nonsurgical management, but findings were potentially influenced by patient age and tumor risk category and highly susceptible to confounding by indication; eligibility for, and receipt of, active surveillance; and timing of surgery was unclear. Conclusions: In patients with small low-risk (primarily papillary) DTC, active surveillance and immediate surgery may be associated with similar mortality, risk of recurrence, and other outcomes, but methodological limitations preclude strong conclusions. Studies of no surgery vs. surgery are difficult to interpret due to clinical heterogeneity and potential confounding factors and are unsuitable for assessing the utility of active surveillance. Research is needed to clarify the benefits and harms of active surveillance and determine outcomes in nonpapillary DTC, larger (>1 cm) cancers, and older patients.

The Concept of Economic Evaluation and Its Application in Thyroid Cancer Research

Economic evaluation is a type of comparative analysis between interventions in terms of both their resource use and health outcomes. Due to the good prognosis of thyroid cancer (TC), the socioeconomic burden of TC patients post-diagnosis is increasing. Therefore, economic evaluation studies focusing on TC are recommended. This study aimed to describe the concept and methods of economic evaluation and reviewed previous TC studies. Several previous studies compared the costs of interventions or evaluated recurrence, complications, or quality of life as measures of their effectiveness. Regarding costs, most studies focused on direct costs and applied hypothetical models. Cost-minimization analysis should be distinguished from simple cost analysis. Furthermore, due to the universality of the term "cost-effectiveness analysis" (CEA), several studies have not distinguished CEA from cost-utility analysis; this point needs to be considered in future research. Cost-benefit analyses have not been conducted in previous TC research. Since TC has a high survival rate and good prognosis, the need for economic evaluations has recently been pointed out. Therefore, correct concepts and methods are needed to obtain clear economic evaluation results. On this basis, it will be possible to provide appropriate guidelines for TC treatment and management in the future.

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.

Multifocality and Progression of Papillary Thyroid Microcarcinoma During Active Surveillance

BACKGROUND

Prospective trials of active surveillance (AS) have shown low rates of progression in low-risk papillary thyroid microcarcinoma (PTMC; T1aN0M0). However, the significance of multifocality as a prognostic factor remains controversial.

METHODS

Data from 571 patients (mean age, 53.1 years; 495 females) who underwent AS were reviewed. PTMC was unifocal in 457 patients (80.0%) and multifocal in 114 patients (20.0%), with 2-5 lesions each (261 tumors in total). Tumor progression was defined as tumor size enlargement ≥ 3 mm and/or development of clinically evident lymph node metastasis (LNM).

RESULTS

After a mean duration of AS of 7.6 years, 53 patients (9.3%) showed tumor enlargement and 8 patients (1.4%) developed LNM. The 10-year progression rate was 13.1%. Age, sex, and calcification pattern did not differ significantly between uni- and multifocal diseases. However, anti-thyroglobulin antibody and/or anti-thyroid peroxidase antibody was more frequently positive with multifocal PTMCs (46.7%) than with unifocal disease (34.4%, p = 0.024). Patients with uni- and multifocal disease showed no significant differences in 10-year rate of tumor enlargement (11.4% vs. 14.8%), LNM development (1.1% vs. 2.4%), or progression (12.4% vs 15.9%). Multivariate analysis of predictors for progression showed multifocality was not a significant risk factor (odds ratio, 1.45; 95% confidence interval, 0.79-2.54; p = 0.22). Eventually, 9 patients (7.9%) with multifocal PTMCs underwent surgery and 7 needed total thyroidectomy, although 7 still showed T1N0M0 low-risk cancer.

CONCLUSIONS

Even patients with multiple PTMCs (T1amN0M0) are good candidates for AS. Many patients can avoid total thyroidectomy and subsequent surgical complications.

Protocol for a Korean Multicenter Prospective Cohort Study of Active Surveillance or Surgery (KoMPASS) in Papillary Thyroid Microcarcinoma

BACKGROUND

A Korean Multicenter Prospective cohort study of Active Surveillance or Surgery (KoMPASS) for papillary thyroid microcarcinomas (PTMCs) has been initiated. The aim is to compare clinical outcomes between active surveillance (AS) and an immediate lobectomy for low-risk PTMCs. We here outline the detailed protocol for this study.

METHODS

Adult patients with a cytopathologically confirmed PTMC sized 6.0 to 10.0 mm by ultrasound (US) will be included. Patients will be excluded if they have a suspicious extra-thyroidal extension or metastasis of a PTMC or multiple thyroid nodules or other thyroid diseases which require a total thyroidectomy. Printed material describing the prognosis of PTMCs, and the pros and cons of each management option, will be provided to eligible patients to select their preferred intervention. For the AS group, thyroid US, thyroid function, and quality of life (QoL) parameters will be monitored every 6 months during the first year, and then annually thereafter. Disease progression will be defined as a ≥3 mm increase in maximal diameter of a PTMC, or the development of new thyroid cancers or metastases. If progression is detected, patients should undergo appropriate surgery. For the lobectomy group, a lobectomy with prophylactic central neck dissection will be done within 6 months. After initial surgery, thyroid US, thyroid function, serum thyroglobulin (Tg), anti-Tg antibody, and QoL parameters will be monitored every 6 months during the first year and annually thereafter. Disease progression will be defined in these cases as the development of new thyroid cancers or metastases.

CONCLUSION

KoMPASS findings will help to confirm the role of AS, and develop individualized management strategies, for low-risk PTMCs.

Adoption of Active Surveillance for Very Low-Risk Differentiated Thyroid Cancer in the United States: A National Survey

CONTEXT

Active surveillance (AS) of thyroid cancer with serial ultrasounds is a newer management option in the United States.

OBJECTIVE

This work aimed to understand factors associated with the adoption of AS.

METHODS

We surveyed endocrinologists and surgeons in the American Medical Association Masterfile. To estimate adoption, respondents recommended treatment for 2 hypothetical cases appropriate for AS. Established models of guideline implementation guided questionnaire development. Outcome measures included adoption of AS (nonadopters vs adopters, who respectively did not recommend or recommended AS at least once; and partial vs full adopters, who respectively recommended AS for one or both cases).

RESULTS

The 464 respondents (33.3% response) demographically represented specialties that treat thyroid cancer. Nonadopters (45.7%) were significantly (P < .001) less likely than adopters to practice in academic settings, see more than 25 thyroid cancer patients/year, be aware of AS, use applicable guidelines (P = .04), know how to determine whether a patient is appropriate for AS, have resources to perform AS, or be motivated to use AS. Nonadopters were also significantly more likely to be anxious or have reservations about AS, be concerned about poor outcomes, or believe AS places a psychological burden on patients. Among adopters, partial and full adopters were similar except partial adopters were less likely to discuss AS with patients (P = .03) and more likely to be anxious (P = .04), have reservations (P = .03), and have concerns about the psychological burden (P = .009) of AS. Few respondents (3.2%) believed patients were aware of AS.

CONCLUSION

Widespread adoption of AS will require increased patient and physician awareness, interest, and evaluation of outcomes.

Effect of Initial Treatment Choice on 2-year Quality of Life in Patients with Low-risk Papillary Thyroid Microcarcinoma

CONTEXT

The long-term quality of life (QoL) in patients with low-risk papillary thyroid microcarcinoma (PTMC) underwent active surveillance (AS) and immediate surgery is unclear.

OBJECTIVE

The aim of this study was to investigate the effect of initial treatment choice on 2-year QoL in patients with low-risk PTMC.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed 2652 QoL surveys from 1055 subjects enrolled in ongoing multicenter prospective cohort study on active surveillance of PTMC, in which the median follow-up duration was 24.4 months.

MAJOR OUTCOME MEASURE

We evaluated QoL of patients with low-risk PTMC according to their treatment modality using generalized estimating equation.

RESULTS

Six hundred and seventy-four subjects (male = 161; mean age = 48.8 ± 11.9 years) with low-risk PTMC chose AS while 381 subjects (male = 75; mean age = 45.7 ± 10.4 years) chose immediate surgery, including lobectomy/isthmusectomy (L/I) and total thyroidectomy (TT). Among the 817 subjects who completed baseline QoL surveys, 2-year QoL was good in order of AS (n = 500), L/I (n = 238), and TT (n = 79) groups after adjustment for age, sex, baseline tumor size, and baseline QoL scores. Among the 101 subjects who changed their treatment from AS to surgery during the follow-up period, 35 subjects who changed treatment due to disease progression had better QoL than 66 subjects who had no disease progression.

CONCLUSIONS

This study identified QoL as a major issue in choosing an initial treatment of low-risk PTMC and highlighted the possibility of using AS as the primary treatment.

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

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

Association of Patient Age With Progression of Low-risk Papillary Thyroid Carcinoma Under Active Surveillance: A Systematic Review and Meta-analysis

Importance

Active surveillance is sometimes considered as a disease management option for individuals with small, low-risk papillary thyroid carcinoma.

Objective

To assess whether patient age is associated with progression of low-risk papillary thyroid carcinoma (tumor growth or incident metastatic disease) in adults under active surveillance.

Evidence Review

Eight electronic databases (MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Emcare, PsycINFO, Web of Science, and ClincalTrials.gov) were searched from inception to March 2019, supplemented with a hand search. Two investigators independently screened citations, reviewed full-text articles, and abstracted data. Additional data were sought from authors. Random-effects meta-analyses were performed using incidence data (statistically adjusted for confounders and crude rates).

Findings

A total of 1658 unique citations were screened, and 62 full-text articles were reviewed, including 5 studies. Three studies included exclusively microcarcinomas and 2 included tumors up to 2 cm in maximal diameter. The mean age of participants was 51.0 to 55.2 years in 4 studies reporting this value. The mean or median follow-up was 5 years or more in 3 studies and approximately 2 years in 2 studies. The pooled risk ratio for tumor growth of 3 mm or more in maximal diameter in individuals aged 40 to 50 years compared with younger individuals was 0.51 when adjusted for confounders (95% CI, 0.29-0.89; 1619 patients, 2 studies), and the unadjusted risk ratio of this outcome for individuals 40 years or older was 0.55 (95% CI, 0.36-0.82; 2097 patients, 4 studies). In adults aged 40 to 45 years, the unadjusted risk ratio for any tumor volume increase compared with younger individuals was 0.65 (95% CI, 0.51-0.83; 1232 patients, 4 studies). The pooled risk ratio for incident nodal metastases in individuals 40 years or older was 0.22 (95% CI, 0.10-0.47; 1806 patients, 3 studies); however, in a secondary analysis, the risk difference was not significantly different. There was no statistically significant heterogeneity in any of the meta-analyses. There were no thyroid cancer-related deaths nor incident distant metastases.

Conclusions and Relevance

This study suggests that older age may be associated with a reduced risk of primary papillary thyroid carcinoma tumor growth under active surveillance. Incident metastatic disease is uncommon during active surveillance.

Experience with Active Surveillance of Thyroid Low-Risk Carcinoma in a Developing Country

Background: The incidence of thyroid carcinoma is growing worldwide. More than 50% of new malignant tumors are classified as classical papillary carcinomas in low-risk category with a low rate of recurrence and high long-term survival. Active surveillance is a strategy to control low-risk tumor evolution with the intention to avoid unnecessary treatments and maintain thyroid function. The aim of this study was to report a cohort of patients with thyroid nodules classified as Bethesda V-VI and who are under active surveillance in Colombia. Methods: A prospective cohort was assembled since January 2015. All patients had been evaluated clinically, biochemically with ultrasonography and fine needle aspiration biopsy previous to the first evaluation. Active surveillance was proposed to patients with asymptomatic low-risk carcinoma (<1.5 cm, encapsulated, without evidence of lymph node metastasis), independent of sex or age. The strategy included a specific discussion about the surgical option and expected risk of complications, risk of long-term thyroxine support, and the active surveillance strategy. The data on age, sex, reason for an ultrasound examination, ultrasound risk by American Thyroid Association (ATA) classification, size and volume of the nodule, reason to consider active surveillance and follow-up ultrasounds, and surgical decision were recorded prospectively. A Kaplan-Meier curve was constructed for the rate of growth and increase in volume of the nodule, growth >3 mm and increase in volume >50%, and need of operation. Results: One hundred two patients were analyzed. Seventy-five percent of patients had a nodule smaller than 1 cm. Only 24/102 (23%) nodules were classified as ATA low risk. Thirty-four of 102 (33.3%) nodules were classified as Bethesda VI and the others were Bethesda V. The median follow-up was 13.9 months, and 32.3% of patients had more than 24 months of follow-up. Only 11/102 (10.8%) nodules grew more than 3 mm and 26/102 (25.5%) nodules grew more than 50% in volume. 12.7% patients were submitted to surgery. The overall stability rate without growth >3 mm, without volume increase >50%, and without surgery at 24 months were 89.8%, 77.0%, and 85.5%, respectively Conclusions: Active surveillance is possible in developing Western countries with similar results to those provided by Asian and American authors.

Active surveillance in low risk papillary thyroid carcinoma

In recent decades, while the incidence of thyroid cancer has increased exponentially around the world, mortality has remained stable. The vast majority of this increase is attributable to the identification of intrathyroidal papillary microcarcinomas, which exhibit slow growth rates with indolent courses. A diagnosis of thyroid cancer based upon the presence of these small tumors could be considered as an overdiagnosis, as the majority of these tumors would not likely result in death if left untreated. Although surgical resection was the classical standard therapy for papillary microcarcinomas, active surveillance (AS) has emerged over the last three decades as an alternative approach that is aimed to recognize a minority group of patients who will clinically progress and would likely benefit from rescue surgery. Despite the encouraging results of AS, its implementation in clinical practice is strongly influenced by psychosocial factors. The aim of this review is to describe the epidemiology, clinical evolution, prognostic factors, and mortality of papillary thyroid microcarcinomas. We also summarize the AS strategy according to published evidence, characterize the criteria for selecting patients for AS according to risk factors and environmental characteristics, as well as analyze the current limitations for AS implementation.

Genomic and Transcriptomic Characteristics According to Size of Papillary Thyroid Microcarcinoma

It is controversial as to whether papillary thyroid microcarcinoma (PTMC) has some genomic and transcriptomic characteristics that differentiate between an early-stage lesion that would eventually evolve into the larger papillary thyroid cancer (PTC), and an occult indolent cancer in itself. To investigate this, we comprehensively elucidated the genomic and transcriptomic landscapes of PTMCs of different sizes, using a large-scaled database. This study included 3435 PTCs, 1985 of which were PTMCs. We performed targeted next-generation sequencing for 221 PTCs and integrated these data with the data including The Cancer Genome Atlas (TCGA) project. The frequency of v-raf murine sarcoma viral oncogene homolog B (BRAF)^V600E mutation was higher in PTMCs >0.5 cm than that in very small PTMCs (≤0.5 cm) and decreased again in PTCs >2 cm. Among PTMCs, the prevalence of mutations in rat sarcoma (RAS) and telomerase reverse transcriptase (TERT) promoter was not significantly different according to their size, but lower than in large PTCs. There was no change in the tumor mutational burden, the number of driver mutations, and transcriptomic profiles with tumor size, among PTMCs and all PTCs. Although a few genes with differential expression and TERT promoter mutations were found in a few PTMCs, our findings showed that there were no useful genomic or transcriptomic characteristics for the prediction of the future progression of PTMC.

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

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

Computed Tomography for Detecting Cervical Lymph Node Metastasis in Patients Who Have Papillary Thyroid Microcarcinoma with Tumor Characteristics Appropriate for Active Surveillance

Background: Active surveillance (AS) has been considered one of the management options in patients with low-risk papillary thyroid microcarcinoma (PTMC). It is important to evaluate clinical lymph node (LN) metastasis to select appropriate candidates with low-risk disease. We investigated the predictive accuracy of computed tomography (CT) for cervical LN metastasis in patients who have PTMC with tumor characteristics appropriate for AS. Methods: This was a retrospective study. Medical records from December 2014 to the end of 2016 were reviewed. Patients who underwent thyroidectomy and who had pathologically confirmed PTMC were included. A total of 464 patients who had tumors with ultrasound (US) characteristics appropriate for AS and who underwent preoperative CT were included in the analysis. Results: CT showed higher diagnostic values especially in positive predictive value (PPV) than US. In patient-based analyses, CT showed low sensitivity and negative predictive value (NPV) (16.0% and 58.5%, respectively), but high specificity and PPV (99.6% and 97.1%, respectively) for detecting cervical LN metastasis. Similar trends were observed for the results of the central neck-level by CT (sensitivity, 14.9%; specificity, 97.4%; PPV, 82.9%; and NPV, 57.4%) in level-by-level analyses. When restricted to lateral neck levels, CT showed high diagnostic accuracy of 95.4% for detecting LN metastasis. In all analyses, CT showed better diagnostic values for cervical LN metastasis than US. Combining US and CT did not improve the diagnostic accuracy compared with CT. Conclusions: In patients with PTMC whose tumor has characteristics suitable for AS, CT had additional benefit after cervical LN assessment by US. Further studies are needed to evaluate routine initial CT scanning for patients who are candidates for AS.

Longitudinal Assessment of Quality of Life According to Treatment Options in Low-Risk Papillary Thyroid Microcarcinoma Patients: Active Surveillance or Immediate Surgery (Interim Analysis of MAeSTro)

Background: In this ongoing multicenter prospective cohort study on active surveillance (AS) in low-risk papillary thyroid microcarcinoma (PTMC), we aimed to compare the quality of life (QoL) of participants based on their choice of treatment, that is, AS or immediate surgery (OP). Methods: QoL of 203 participants who chose AS and 192 participants who underwent OP was evaluated using a thyroid-specific QoL questionnaire at diagnosis and during follow-up (median 8 months). Results: The mean ages of the participants in the AS and OP groups were 47.3 ± 11.7 and 45.6 ± 10.5 years (p = 0.138), respectively, and the mean tumor sizes were 5.7 ± 1.6 and 6.5 ± 2.1 mm (p = 0.065), respectively. At baseline, significantly better psychological health (7.1 ± 1.3 vs. 6.8 ± 1.6, p = 0.023) and overall health (6.8 ± 1.2 vs. 6.5 ± 1.3, p = 0.018) were observed in the AS group than in the OP group. During follow-up, significantly better physical (7.9 ± 1.1 vs. 7.4 ± 1.2, p < 0.001), psychological (7.4 ± 1.3 vs. 6.9 ± 1.6, p = 0.004), and overall health (6.9 ± 1.0 vs. 6.5 ± 1.1, p = 0.002) were observed in the AS group than in the OP group, whereas spiritual health was comparable between the two groups. Compared with the AS group, the OP group experienced more fatigue, changes in voice and appearance, less satisfaction, and low fear of recurrence. The self-assessed financial burden was similar at baseline and follow-up in both groups. Conclusion: The QoL of PTMC patients is different according to the type of treatment. Better psychological health at baseline and physical and psychological health at follow-up were observed in the AS group than in the OP group. However, studies with longer follow-up periods are needed.

Ultrasound-guided percutaneous laser ablation for papillary thyroid microcarcinoma: a retrospective analysis of 37 patients

BACKGROUND

Over the past ten years, more papillary thyroid microcarcinoma (PTMC) has been diagnosed more frequently due to the development of imaging technology, and the incidence of PTMC has increased significantly. Ultrasound-guided percutaneous laser ablation (PLA) is mainly used for benign thyroid nodules, and few studies have been published on the use of PLA for PTMC. In the present study, a retrospective analysis was performed to explore the efficacy of PLA for PTMC.

METHODS

A total of 37 patients with PTMC who underwent PLA were included in this study. Measurement of the lesion volume and serum thyroid hormone levels and clinical evaluation were performed at 1, 3, 6, and 12 months and every 6 months thereafter.

RESULTS

We found that all patients were successfully treated with PLA without serious complications. At the last follow-up visit, 12/37 (32.4%) primary lesions had disappeared, and 24/37 (64.9%) remained as cicatricial hyperplasia. One patient (2.7%) had cervical lymph node metastasis at 24 months post-operatively and underwent open surgery.

CONCLUSION

Our initial studies suggest that ultrasound-guided PLA is a safe and effective treatment for 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.

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.