Natural history of papillary thyroid microcarcinoma: Kinetic analyses on tumor volume during active surveillance and before presentation

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.

Aspirin Use Is Not Associated with Lower Thyroid Cancer Risk: A Nationwide Nested Case-Control Study

Background: While aspirin use is known to be associated with reduced incidence of various cancer types, it is unclear whether this benefit extends to thyroid cancer. We aimed to evaluate the association between aspirin use and thyroid cancer development. Methods: This nested case-control study used nationwide data from the Korean National Health Insurance Service-National Sample Cohort 2002-2015. In total, 4547 individuals with newly developed thyroid cancer were matched with 13,641 controls based on age, sex, and follow-up period. Odds ratios (ORs) and 95% confidence intervals (CIs) for thyroid cancer development according to aspirin use were analyzed using a multivariable conditional logistic regression model. Results: The number of days for which patients with thyroid cancer used aspirin (the proportions of no use, <30 days/year, 30-90 days/year, and ≥90 days/year were 93.03%, 6.51%, 0.31%, and 0.15%, respectively) was comparable with that of the controls (p = 0.371, chi-squared test). The risk of thyroid cancer development was not associated with the duration of aspirin use (ORs [CI] for aspirin use <30 days/year, 30-90 days/year, and ≥90 days/year were 1.11 [0.96-1.28], 1.01 [0.54-1.88], and 1.23 [0.50-3.06], respectively, compared with no use) after adjusting for body mass index, smoking status, hypertension, Charlson comorbidity index, and number of outpatient visits per year. In addition, subgroup analyses stratified by age, sex, and follow-up duration did not reveal any significant association between aspirin use and thyroid cancer. Conclusions: Our findings suggest that even extended aspirin use may not impact the prevention or onset of thyroid cancer.

Understanding surgical decision-making in older adults with differentiated thyroid cancer: A discrete choice experiment

BACKGROUND

Prior studies demonstrated that older adults tend to undergo less surgery for thyroid cancer. Our objective was to use a discrete choice experiment to identify factors influencing surgical decision-making for older adults with thyroid cancer.

METHODS

Active and candidate members of the American Association of Endocrine Surgeons were invited to participate in a web-based survey. Multinomial logistic regression was utilized to assess patient and surgeon factors associated with treatment choices.

RESULTS

Complete survey response rate was 25.7%. Most respondents were high-volume surgeons (88.5%) at academic centers (76.9%). Multinomial logistic regression demonstrated that patient age was the strongest predictor of management. Increasing age and comorbidities were associated with the choice for active surveillance (P = .000), not performing a lymphadenectomy in patients with nodal metastases (relative-risk ratio: 2.5, 95% CI: 1.4-4.2, P = .002 and relative-risk ratio: 1.6, 95% CI: 1.2-2.1, P = .004, respectively), and recommending hemithyroidectomy versus total thyroidectomy for a cancer >4 cm (relative-risk ratio: 4.4, 95% CI: 2.5-7.9, P = .000 and relative-risk ratio: 3.4, 95% CI: 2.3-5.1, P = .000, respectively). Surgeons with ≥10 years of experience (relative-risk ratio: 3.3, 95% CI: 1.1-10.3, P = .039) favored total thyroidectomy for a cancer <4 cm, and nonfellowship trained surgeons (relative-risk ratio: 7.3, 95% CI: 1.3-42.2, P = .027) opted for thyroidectomy without lymphadenectomy for lateral neck nodal metastases.

CONCLUSION

This study highlights the variation in surgical management of older adults with thyroid cancer and demonstrates the influence of patient age, comorbidities, surgeon experience, and fellowship training on management of this population.

Lymph node metastasis in young and middle-aged papillary thyroid carcinoma patients: a SEER-based cohort study

BACKGROUND

Lymph node metastasis (LNM) occurs frequently in young papillary thyroid carcinoma (PTC) patients, though the mortality rates are low. We aimed to analyze the relationship between age at diagnosis and LNM in PTC at a population level to elucidate the clinical behavior of PTC.

METHODS

Data of adult patients with surgically treated PTC and follicular thyroid carcinoma (FTC) were identified from the Surveillance, Epidemiology, and End Results (SEER) database (2004-2015) to investigate the relationship between age and clinical characteristics by curve estimation. The adjusted odds ratio of age and LNM rate were determined.

RESULTS

A total of 50,347 PTC (48,166) and FTC (2181) (median age: 45 and 50 years, respectively) patients met the inclusion criteria; 44.5% of those with PTC (21,428) had LNM. Rank-sum test analysis indicated differences in distribution of age in LNM-positive and LNM-negative PTC. The relationship between age, tumor size and LNM showed a quadratic curve in PTC. The mean tumor diameter and LNM rate correlated linearly with age in 18-59-year-old patients. LNM rate decreased with age (R² = 0.932, P < .0001), especially women (R² = 0.951, P < .0001).

CONCLUSION

In young and middle-aged PTC patients, LNM may resolve spontaneously with delayed diagnosis and management. Active surveillance of low-risk PTC is justified.

Active surveillance for patients with very low-risk thyroid cancer

Over the past 30 years in the United States, increasing identification of small thyroid nodules has led to a dramatic rise in the detection of small thyroid cancers, many of which are unlikely to progress to overt clinical disease. Because autopsy studies reveal that up to 30% of people harbor clinically occult thyroid cancers, the growing use of diagnostic technologies has identified an increasing number of small, clinically low risk papillary thyroid cancers (PTCs). In recent years, clinical practice has evolved to de-intensify the treatment for PTCs, with fewer total thyroidectomy and nodal dissection procedures being performed, in favor of more limited operations. In addition, vigilant observation of selected low risk cancers has demonstrated outcomes comparable to those patients who undergo immediate surgical intervention. Active surveillance has emerged as a new option within the treatment algorithm of PTCs. There is now robust data from cancer centers in Japan and Korea which have reported excellent oncologic outcomes among patients undergoing active surveillance for PTC, as well as more recent, similar data from the United States. American Thyroid Association guidelines now include the option of active surveillance for appropriately selected patients with low-risk PTC. With active surveillance now one option within the standard of care for patients with certain thyroid cancers, surgeons have become critical to facilitating shared decision-making for patients facing this diagnosis.

Active surveillance as a management strategy for papillary thyroid microcarcinoma

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

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

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

Kinetic Analysis of Growth Activity in Enlarging Papillary Thyroid Microcarcinomas

Background: Although papillary thyroid microcarcinoma (PMC) is generally stable on active surveillance, conversion surgery is recommended for enlarging tumors. However, it remains unclear which enlargement threshold should be considered sufficient to trigger surgery. This study analyzed changes in the growth activity of PMC, before and after enlargement. Methods: We enrolled 824 patients with PMC, in whom active surveillance was initiated between 2005 and 2011 (median duration of follow-up: 6.04 years). Changes in the maximal tumor size and tumor volume were evaluated. Point of enlargement (PE) was defined as the time at which maximal tumor size or tumor volume had increased by ≥3 mm (PE-M) or by ≥50% (PE-V), respectively. In patients with PMC who underwent at least three ultrasound examinations during the study period, we compared the tumor doubling rates (TDRs, designated as the inverse of doubling time) between pre- and post-PEs. Results: Ten-year enlargement-free survival rates based on maximal tumor size and tumor volume were 86.9% and 54.9%, respectively. The median post-PE TDRs was significantly lower than that of pre-PEs (-0.091/year vs. 0.509/year [p < 0.001] for PE-M, and -0.058/year vs. 0.370/year [p < 0.001] for PE-V), indicating decreased tumor growth after PEs. After PE-M and PE-V, the PMCs continued to rapidly enlarge (TDR >0.5/year) in only 6 (7.7%) and 11 (3.8%) patients and moderately enlarge (TDR 0.1-0.5/year) in 10 (12.8%) and 35 (12.1%) patients, respectively. Conversely, tumors shrank (TDR < -0.1/year) in 37 (47.4%) and 105 (36.1%) patients, respectively, and remained stable (TDR ranged between 0.1/year and -0.1/year) in 25 (32.1%) and 140 (48.1%) patients, respectively. Conclusion: Since most PMCs demonstrate a significant decrease in growth activity after enlargement, performing surgery immediately after the PE may be premature.

Active Surveillance Versus Immediate Surgery: Questionnaire Survey on the Current Treatment Strategy for Adult Patients with Low-Risk Papillary Thyroid Microcarcinoma in Japan

Background: Two Japanese prospective trials of active surveillance (AS) for adult patients with low-risk papillary thyroid carcinoma (PTC) ≤1 cm (cT1aN0M0 PTMC) have verified the safety of AS in oncological control and its superiority over immediate surgery with respect to unfavorable outcomes. Thus, AS has been accepted as an alternative to immediate surgery for asymptomatic papillary thyroid microcarcinomas (PTMCs). However, the real-world clinical approach for PTMC is unknown. Thus, this study aimed to investigate the current state of management of asymptomatic PTMCs in Japan. Methods: We conducted a questionnaire survey on the actual treatment patterns for adult patients with low-risk PTMCs. The subjects were member institutions of the Japan Association of Endocrine Surgery (JAES) or Japanese Society of Thyroid Surgery (JSTS), including the departments of surgery and head and neck surgery (HNS). Results: Responses were obtained from 134 institutes, where 72.4% of Japanese thyroid cancer cases operated by surgeons were treated. For suspicious tumors on ultrasound, 18 responders (13.4%) conducted cytological examination routinely, while 69 (51.5%) and 40 (27.8%) conducted it only for tumors >5 and >10 mm, respectively. After the diagnosis, 42 responders (31.3%) recommend AS, 35 (26.1%) recommend immediate surgery as the management, and 52 (38.8%) allowed patients to decide the treatment course. The present responders tended to recommend surgery for PTMCs that were located adjacent to the dorsal surface of the thyroid, were multiple, or measured almost 10 mm in size. At these institutions, 1176 patients with PTMC underwent surgery in 2017, accounting for 18.1% of surgeries for PTC. During the succeeding three months, 310 of 576 (53.8%) PTMC patients underwent AS. The treatment strategies did not differ between the departments (Surgery or HNS). The institutions that have six or more surgeons, that were located in metropolitan areas, or that were certified by JAES or JSTS performed AS more actively. Conclusion: More than 50% of low-risk PTMCs are on AS in Japan. However, the indication and recommendation for AS vary significantly between institutions. To improve the implementation of this management modality, physicians and patients should be further educated, and the sociomedical environment should be improved.

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

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

Active surveillance 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.