Clinical, histopathological, and molecular characteristics of papillary thyroid microcarcinoma

Causal inference between aggressive extrathyroidal extension and survival in papillary thyroid cancer: a propensity score matching and weighting analysis

Background

Extrathyroidal extension is a major risk factor for poor prognosis in papillary thyroid cancer. However, the effect of different degrees of extrathyroidal extension on prognosis remains controversial. We performed a retrospective study to elucidate how the extent of extrathyroidal extension in papillary thyroid cancer affected the clinical prognosis of patients and its covariates.

Methods

The study included 108,426 patients with papillary thyroid cancer. We categorized the extent of extension into none, capsule, strap muscles, and other organs. Three causal inference methods for retrospective studies, namely, inverse probability of treatment weighting, standardized mortality ratio weighting, and propensity score matching analysis, were used to minimize potential selection bias. Kaplan-Meier analysis and univariate Cox regression analyses were applied to analyze the precise effect of ETE on survival in papillary thyroid cancer patients.

Results

In the Kaplan-Meier survival analysis, only extrathyroidal extension into or beyond the strap muscles was statistically significant for both overall survival (OS) and thyroid cancer-specific survival (TCSS). In univariate Cox regression analyses before and after matching or weighting based on causal inference, extrathyroidal extension into soft tissues or other organs is a high-risk factor for both overall survival and thyroid cancer-specific survival. Sensitivity analysis revealed that lower overall survival was observed in patients with older age (≥55) and larger tumor size (>2 cm) of papillary thyroid cancer with extrathyroidal extension into or beyond the strap muscles.

Conclusions

Our study indicates that extrathyroidal extension into soft tissues or other organs is a high-risk factor in all papillary thyroid cancer. Even though invasion into the strap muscles did not seem to be a marker for poor prognosis, it still impaired the overall survival of patients with older age (≥55 years old) or larger tumor size (>2 cm). Further investigation is needed to confirm our results and to clarify further risk factors independent of extrathyroidal extension.

Association between preoperative serum TSH and tumor status in patients with papillary thyroid microcarcinoma

Thyroid-stimulating hormone (TSH) is a growth factor affecting the initiation or progression of papillary thyroid cancer (PTC). However, the relationship between preoperative serum TSH and papillary thyroid microcarcinoma (PTMC) remains controversial. To investigate the relationship between preoperative serum TSH and tumor status of PTMC, a multicentered retrospective study was performed from January 2014 to December 2016. The cohort of this study consisted of 1997 patients who underwent thyroid surgery. Serum TSH concentrations were measured and PTMC was diagnosed based on the post-operation pathological report. Results showed that the preoperative serum TSH concentration was not related to age and gender but was positively associated with tumor size. Furthermore, higher TSH level was associated with extra-thyroidal extension and lymph node metastasis (LNM). These results indicated that TSH might not be involved in the development of PTMC but may be associated with PTMC progression. Preoperative serum TSH concentration should be considered as risk predictor for tumor progression in patients with PTMC.

Ultrasonographical, clinical and histopathological features of 1264 nodules with papillary thyroid carcinoma and microcarcinoma based on tumor size

Objective

We aimed to evaluate the patients diagnosed with papillary thyroid carcinoma (PTC) and papillary thyroid microcarcinoma (PTMC) in terms of clinical, ultrasonographical (US) and histopathological features and their relationships with tumor size.

Methods

We retrospectively evaluated 881 patients who underwent thyroid surgery in our clinic and diagnosed with PTC histopathologically were enrolled the study. Demographic characteristics, US findings and histopathological features were evaluated.

Results

In total, 1264 nodules were identified in the 881 patients. The incidentality rates were higher in the PTMC group and also in the ≤ 5 mm group. In total multifocality rate was 32.9%, and was significantly higher in PTMC group than the PTC group. PTC and > 5 mm PTMC groups compared to PTMC and ≤ 5 mm groups respectively, were more aggresive histopathological features.

Conclusion

Since the incidentality rates were found significantly more common in our patients with PTMC and those with ≤ 5 mm, ultrasonographic features of the nodules should be evaluated carefully and for cases which are suspicious with US, US-guided fine needle aspiration biopsy (FNAB) should be considered in order to make the correct treatment strategy. Also our study revealed that PTC and > 5 mm PTMC groups compared to PTMC and ≤ 5 mm groups respectively, have more aggresive histopathological features.

Risk Factors for Central and Lateral Lymph Node Metastases in Patients With Papillary Thyroid Micro-Carcinoma: Retrospective Analysis on 484 Cases

BACKGROUND

Papillary thyroid micro-carcinoma (PTMC) is defined as a tumor with a larger diameter ≤1 cm which has an indolent course and satisfying prognosis. However, the incidence of lymph node metastasis of PTMC cannot be ignored. The aim of this study was to assess the incidence of lymph node metastasis in PTMC patients, as well as to evaluate the risk factors for both central lymph node metastases (CLNM) and lateral lymph node metastases (LLNM).

METHODS

Patients who underwent thyroidectomy from January 2017 to October 2020, and pathologically diagnosed with PTMC were enrolled in our study and their medical records were collected and analyzed.

RESULTS

A total of 484 PTMC patients were included. The incidence of central and lateral lymph node metastasis was 49.6% and 9.1%, respectively. Multivariate analysis demonstrated as independent risk factors for CLNM male sex, age <40 years, largest tumor size ≥5 mm and bilaterality. Extrathyroidal extension, presence of CLNM, number of CLNM ≥5 were strong indicators for LLNM.

CONCLUSION

The incidence of lymph node metastases in PTMC is non-negligible. The identification of potential risk factors for CLNM and LLNM would help tailor individual surgical interventions for patients with PTMC.

Active Surveillance of Thyroid Microcarcinoma-Can This Approach Be Safely Implemented Worldwide?

The incidence of thyroid cancer has been increasing exponentially worldwide, mainly due to increased detection of small papillary thyroid microcarcinomas (PTMCs). Given the indolent nature of the disease, active surveillance (AS) has been suggested as an alternative approach to immediate surgery in the management of low-risk PTMCs. The decision to proceed with AS must take into account patient characteristics, tumor characteristics, and medical team characteristics. In this review, we discuss the rationale and evidence to support AS, as well as important considerations and limitations to implementing this approach for PTMC worldwide.

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

BACKGROUND

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Geographic influences in the global rise of thyroid cancer

The incidence of thyroid cancer is on the rise, and this disease is projected to become the fourth leading type of cancer across the globe. From 1990 to 2013, the global age-standardized incidence rate of thyroid cancer increased by 20%. This global rise in incidence has been attributed to several factors, including increased detection of early tumours, the elevated prevalence of modifiable individual risk factors (for example, obesity) and increased exposure to environmental risk factors (for example, iodine levels). In this Review, we explore proven and novel hypotheses for how modifiable risk factors and environmental exposures might be driving the worldwide increase in the incidence of thyroid cancer. Although overscreening and the increased diagnosis of possibly clinically insignificant disease might have a role in certain parts of the world, other areas could be experiencing a true increase in incidence due to elevated exposure risks. In the current era of personalized medicine, national and international registry data should be applied to identify populations who are at increased risk for the development of thyroid cancer.

Deciphering novel biomarkers of lymph node metastasis of thyroid papillary microcarcinoma using proteomic analysis of ultrasound-guided fine-needle aspiration biopsy samples

Thyroid papillary microcarcinoma is now a common clinical problem. Cervical lymph node metastasis is the main metastasis mode of PTMC. However, before operation, it is still difficult to determine exactly whether PTMC patient is suffering with cervical lymph node metastasis. To resolve this dilemma, for better selection of optimum treatment plans, it is necessary to investigate the overall changes in proteomes of PTMC, and evaluate the potential of biomarkers to predict lymph node metastasis. Tandem mass tags combined with multidimensional liquid chromatography and mass spectrometry analyses were used aiming to screen the proteomic profiles of fine-needle aspiration biopsy samples. Quantitative proteomic analysis, significant pathway and functional categories were investigated. In total, 3391 proteins of the 3793 protein groups identified were quantified. Bioinformatics analysis indicated that differentially expressed proteins were involved in multiple biological functions, metastasis-related pathways. Moreover, IFN-stimulated gene 15 proteins were found to be well distinguished between patients with lymph node metastatic and patients with nonmetastatic PTMC. Knocking down ISG15 with shRNA inhibited the xenografted tumor growth. This study provided a reference proteome map for lymph node metastatic PTMC. ISG15 probably is a prognosis marker of thyroid papillary microcarcinoma patients with lymph node metastasis. SIGNIFICANCE: Nowadays, thyroid cancer has become a widespread epidemic. The rate of thyroid cancer incidence has been faster than any other cancers, reported by the American Cancer Society. Papillary thyroid microcarcinoma (PTMC) is a subset of PTC defined as PTC measuring≤1 cm in size, which comprises nearly one-half of all the cases of PTCs. Actually, the rapidly increasing global incidence of PTC is mainly attributed to the corresponding increase in the diagnosis of PTMC. Scholars have figuratively compared the increase of PTMC to the "tsunami". The treatment scheme for PTMC is still not uniform, and the controversy is mainly focused on the necessity of surgery treatment. PTMCs often have an indolent course in the absence of evidence of metastatic cervical lymph nodes, distant metastases and extrathyroidal extension. Therefore, it is important for us to reliably differentiate the small number of PTMC patients developing significant metastases progression from the larger population of patients that harbor indolent PTMCs. The present study aimed to investigate the overall changes in proteomes of PTMC, and evaluate the potential of biomarkers to predict lymph node metastasis. Tandem mass tags (TMT) combined with multidimensional liquid chromatography and mass spectrometry analyses were used aiming to screen the proteomic profiles of fine-needle aspiration biopsy (FNAB) samples. Quantitative proteomic analysis, significant pathway and functional categories were investigated. Our results showed that some differential expression proteins were likely to be important resources for finding new diagnostic biomarkers.

A cancer of undetermined significance: Incidental thyroid carcinoma

INTRODUCTION

The incidence of thyroid cancer is increasing which can be attributed in part to improved ultrasonography (US) methods and increased detection of incidental thyroid carcinomas (ITC). We aimed to compare ITC with nonincidental thyroid carcinomas (NITC) in this study.

METHODS

Retrospective analyses of 906 individual patients who were operated for benign and malignant thyroid disease and had a final histopathological diagnosis of thyroid carcinoma were enrolled in this study. Preoperative US examination and fine needle aspiration (FNA) biopsy results were evaluated. The tumor foci in thyroidectomy specimens that were not represented in preoperative US or FNA reports were classified as ITC. The tumor foci that match with the lesions defined in US or FNA results were classified as NITC.

RESULTS

Final histology revealed ITC in 326 patients (36%) and NITC in 580 patients (64% Mean age was 51.7 ± 11.11 in ITC group and 48.15 ± 13.1 in NITC group (P < .001). In NITC group 322 (55.5%) of the patients were operated for suspicious cytology while only 29 (8.9%) of the patients in the ITC group were operated because of this indication (P < .001). There were 1301 cancer foci in histopathology specimens. Among all these cancer foci, 434 (33.3%) were detected incidentally and 867 (66.7%) were detected non-incidentally. About 779 (89.9%) of nonincidental cancer foci were papillary cancer (PTC), while all of the incidental cancer foci were PTC. Mean size was 13 mm in NITC group and it was 3 mm in the ITC group and differed significantly between the groups (P < .001). Tumor size was ≤1 cm in 35.2% of the patients with NITC while 98.5% of patients with ITC had tumor ≤1 cm. The occurrence of multinodularity was higher in ITC than the NITC group (P < 001). Median TSH level was higher in patients with NITC than ITC while both were in the reference range (1.53 vs 1.03 μIU/mL, P < .001). The frequency of thyroiditis detected by US, and thyroid peroxidase antibody and thyroglobulin antibody positivities were similar in patients with ITC and NITC (P = .2, P = .86, and P = .26, respectively). The frequencies of capsular invasion (29.1% vs 7.9%), extrathyroidal extension (13% vs 4.2%), multifocality (35.8% vs 24.2%), non-complete resection (9.2% vs 1.8%), and lymph node metastasis (9.5% vs 1.8%) were significantly higher in the NITC group (P < .001, for each). Persistent/recurrent disease in patients with NITC was more frequent than patients with ITC (P = .004). This outcome was similar for cancers measuring ≤1 cm (P = .001).

CONCLUSION

ITC is often encountered in older patients and frequently determined in early stages with more favorable histopathological features and better prognosis.

The diagnostic and prognostic values of Ki-67/MIB-1 expression in thyroid cancer: a meta-analysis with 6,051 cases

Background

Growing evidence has demonstrated that Ki-67/MIB-1 has an effect on the clinical progression and prognosis in cancers. However, the diagnostic and prognostic values of Ki-67/MIB-1 in thyroid cancer remain unclear.

Materials and methods

The meta-analysis was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were retrieved from PubMed, EBSCO, EMBASE, ISI Web of Science, China National Knowledge Infrastructure, WanFang and Chinese VIP databases. MetaDiSc and STATA12.0 were used to analyze the meta-analysis. Fixed-effect analysis and random-effect analysis were applied to pool the relative ratio based on heterogeneity in this meta-analysis.

Results

In the meta-analysis, 51 eligible studies were included. The pooled sensitivity of Ki-67/MIB-1 was 0.61 (95% confidence interval [CI]: 0.59–0.63) and specificity was 0.75 (95% CI: 0.74–0.77) in thyroid cancer. The pooled positive likelihood ratio was 3.19 (95% CI: 2.30–4.42) and negative likelihood ratio was 0.43 (95% CI: 0.35–0.54). In the diagnosis of thyroid cancer, the pooled diagnostic odds ratio of Ki-67/MIB-1 was 8.54 (95% CI: 5.03–14.49). The area under the symmetric receiver operating characteristic curve was 0.804 (standard error =0.031). Our results showed that there were statistical associations between Ki-67/MIB-1 and age (odds ratio [OR] =1.71, 95% CI: 1.14–2.57, P=0.010), tumor size (OR =1.86, 95% CI: 1.17–2.96, P=0.008), lymph node metastasis (OR =2.49, 95% CI: 1.42–4.39, P=0.002), metastasis status (OR =6.96, 95% CI: 2.46–19.69, P<0.001), tumor node metastasis stage (OR =6.56, 95% CI: 3.80–11.34, P<0.001) and extrathyroid extension (OR =1.91, 95% CI: 1.27–2.87, P=0.002). Furthermore, thyroid cancer patients with a high level of Ki-67/MIB-1 had a worse disease-free survival as compared to patients with a low level of Ki-67/MIB-1 (hazard ratio =5.19, 95% CI: 3.18–8.46, P<0.001). Also, Ki-67/MIB-1 was found to be associated with increased risk of mortality (hazard ratio =3.56, 95% CI: 1.17–10.83, P=0.025).

Conclusion

Our results demonstrated that Ki-67/MIB-1 might act as a potential factor in diagnosing thyroid cancer in Chinese. Also, the meta-analysis indicated that Ki-67/MIB-1 might have an effect on prognosis in non-Chinese thyroid cancer patients.

The Genetics of Papillary Microcarcinomas of the Thyroid: Diagnostic and Prognostic Implications

Papillary microcarcinoma of the thyroid (mPTC) is defined by the WHO as a papillary thy-roid cancer measuring 10mm or less in diameter and it is nowadays a topic of intense debate among the members of the medical community due to its apparent “epidemic” rise. Although these tumors follow almost always an indolent clinical course and carry an excellent prognosis, it is known that a small sub-set may display a potentially aggressive behavior. Nevertheless, we still lack an accurate way of predict-ing those which will cause significant disease. In an attempt to address this problem, a number of clini-co-pathologic features have been studied as poor prognostic markers in mPTC, and their association with known genetic alterations in thyroid cancer has been evaluated. Herein we review the present knowledge concerning mPTC’s genetic profile, namely the prevalence of BRAF (V600E), RAS and TERT promoter mutations and RET/PTC and PAX8-PPARG rearrangements and report the results of the evaluation in the putative prognostic value of these genetic alterations in mPTC.

Clinicopathologic Factors and Thyroid Nodule Sonographic Features for Predicting Central Lymph Node Metastasis in Papillary Thyroid Microcarcinoma: A Retrospective Study of 1204 Patients

OBJECTIVES

Preoperative prediction of lymph node metastasis is of clinical importance for the surgical treatment of thyroid tumor. The purpose of this study was to evaluate clinicopathologic factors and thyroid nodule sonographic features predictive of central lymph node metastasis in papillary thyroid microcarcinoma.

METHODS

Clinicopathologic factors and thyroid nodule sonographic features of 1204 patients with papillary thyroid microcarcinoma were retrospectively reviewed from January 2014 to June 2015. Central lymph node dissection was performed on each patient. Univariate and multivariate analyses were performed to analyze the clinicopathologic factors and thyroid nodule sonographic features associated with central lymph node metastasis in papillary thyroid microcarcinoma. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the relevance of all potential predictive factors.

RESULTS

Central lymph node metastasis was detected in 395 of the 1204 patients (32.81%). By univariate and multivariate analyses, younger age (≤43 years), male sex, larger tumor size (≥7 mm), multifocal papillary thyroid microcarcinoma and microcalcification were independently associated with central lymph node metastasis in papillary thyroid microcarcinoma (P < .05). The ORs were 1.920 (95% CI, 1.476-2.499), 1.665 (95% CI, 1.234-2.247), 1.534 (95% CI, 1.177-2.000), 2.120 (95% CI, 1.563-2.877), and 4.109 (95% CI, 3.118-5.414), respectively.

CONCLUSIONS

Central lymph node metastasis is highly prevalent in papillary thyroid microcarcinoma. Younger age (≤43 years), male sex, larger tumor size (≥7 mm), multifocal papillary thyroid microcarcinoma, and microcalcification were independent predictors of central lymph node metastasis. Surgeons and radiologists need to pay more attention to patients with papillary thyroid microcarcinoma who have these risk predictors.

Incidental and non-incidental thyroid microcarcinoma

There is no clear therapeutic approach for thyroid microcarcinoma (TMC). This may be as a consequence of recent observations that have reported biologically different types of TMC, which should be treated differently. The objective of the present study was to compare incidental TMC (ITMC) and non-incidental TMC (NITMC) in order to assess the differences in the incidence, diagnostic results, clinicopathological characteristics and surgical treatment. The study consisted of a retrospective chart review of 3,218 patients consecutively admitted and surgically treated in a single institution due to thyroid pathology. A total of 246 (7.64%) patients presented with a thyroid malignancy, and 97 (39.43%) of these individuals were diagnosed with TMC; 37 (38.14%) patients exhibited ITMC and 60 (61.86%) exhibited NITMC. All 37 (100.00%) patients with ITMC exhibited a papillary type of cancer. In the NITMC group, 1 (1.67%) patient presented with follicular microcarcinoma, 1 (1.67%) individual with papillary- and follicular-type microcarcinoma, 1 (1.67%) individual with medullary microcarcinoma, and the remaining 57 (95.00%) patients presented with papillary microcarcinoma. The number of younger patients (<45 years old) was higher in the NITMC group, but this difference was not significant (P=0.205). In all patients with ITMC, ultrasound-guided fine-needle aspiration biopsy did not reveal malignant processes. In the NITMC group, the number of larger tumors (>5 mm) was significantly higher compared with that in the ITMC group (P<0.001). ITMC was significantly associated with multinodular goiter (MNG) (P<0.001). Amongst the NITMC group, 18.33% of patients presented with cervical lymph node involvement (P<0.001). Overall, the incidence of TMC is high, and consists of ITMC and NITMC, although the prevalence of NITMC is higher than that of ITMC. The majority of ITMCs and NITMCs are composed of a papillary type of cancer. The majority of ITMCs have dimensions ≤5 mm in diameter and are significantly associated with MNG. In comparison with ITMC, NITMC more often presents with aggressive features such as cervical lymph node metastases, so the surgical approach to this tumor should be more radical.

Intraoperative frozen section for the evaluation of extrathyroidal extension in papillary thyroid cancer

BACKGROUND

We investigated extrathyroidal extension (ETE) through frozen biopsy for intraoperative decision making in patients with papillary thyroid cancer (PTC).

METHODS

During the period of the study an operation was performed in 268 patients with PTC and ETE was evaluated using intraoperative frozen biopsies of thyroid tissue.

RESULTS

Extrathyroidal extension was confirmed in 54 patients (20 %) on frozen biopsy. Fifty-three patients among 54 patients showing ETE on frozen biopsy were confirmed on permanent pathologic analysis. Accordingly, frozen biopsy had a sensitivity of 66 %, a specificity of 99 %, a positive predictive value of 98 %, and a negative predictive value of 87 %. Tumor size (OR 4.373; CI 2.257-8.475, p = <0.001) was an independent factor for predicting ETE on frozen biopsy.

CONCLUSIONS

Intraoperative frozen biopsy can be an useful tool in identifying the presence of ETE. It can also help the operator decide the extent of surgery and central neck dissection in patients with PTC.

Sorafenib in the treatment of thyroid cancer

Sorafenib has been evaluated in several Phase II and III studies in patients with locally advanced/metastatic radioactive iodine-refractory differentiated thyroid carcinomas (DTCs), reporting partial responses, stabilization of the disease and improvement of progression-free survival. Best responses were observed in lung metastases and minimal responses in bone lesions. On the basis of these studies, sorafenib was approved for the treatment of metastatic DTC in November 2013. Few studies suggested that reduction of thyroglobulin levels, or of average standardized uptake value at the fluorodeoxyglucose-PET, could be helpful for the identification of responding patients; but further studies are needed to confirm these results. Tumor genetic marker levels did not have any prognostic or predictive role in DTC patients.The most common adverse events observed included skin toxicity and gastrointestinal and constitutional symptoms. Encouraging results have also been observed in patients with medullary thyroid cancer. Many studies are ongoing to evaluate the long-term efficacy and tolerability of sorafenib in DTC patients.

Lateral neck recurrence from papillary thyroid carcinoma: Predictive factors and prognostic significance

OBJECTIVES/HYPOTHESIS

The aim of this study was to identify any possible predictive factors of lateral neck recurrence in patients with papillary thyroid carcinoma with no ultrasonographic and/or cytological evidence of lymph node metastasis at time of diagnosis. The influence of lateral neck recurrence on survival was also investigated.

STUDY DESIGN

Observational retrospective study.

METHODS

Retrospective review of clinical records of 610 patients surgically treated for papillary thyroid carcinoma with clinically negative lymph nodes at the Otolaryngology Unit of the Arcispedale Santa Maria Nuova-IRCCS, Reggio Emilia, Italy, from January 1984 to December 2008.

RESULTS

Lateral neck recurrences were ipsilateral to the primary tumor in all cases and were associated with the occurrence of more aggressive histological variants and central neck metastasis. Lateral neck recurrences were more frequently observed in patients with distant metastases and were associated with a reduced disease-specific survival.

CONCLUSION

Lateral neck compartment ipsilateral to the tumor was the most common site of recurrence, with about half of cases appearing in the first 28 months of follow-up. In patients with papillary thyroid carcinoma, detection of lateral neck metastases prior to first surgery is crucial to surgical planning. Aggressive histological variants and postsurgical evidence of lymph node metastasis from papillary thyroid carcinoma in central neck compartment are associated with a higher risk of lateral neck recurrence. In these patients, a closer postsurgical ultrasound surveillance of the lateral neck compartments seems worthwhile.

LEVEL OF EVIDENCE

4.

Tumor sprouting in papillary thyroid carcinoma is correlated with lymph node metastasis and recurrence

BACKGROUND

Identification of poor prognostic factors in papillary thyroid carcinoma (PTC) patients is important for the patients' care and follow-up. We can sometimes see small tumor clusters without desmoplasia and no evidence of lymphatic emboli around the main tumor mass of PTC. We termed this form of tumor clustering, 'tumor sprouting,' and determined whether these tumors correlate with lymphovascular invasion, lymph node metastasis, and recurrence.

METHODS

We analyzed a total of 204 cases of papillary thyroid macrocarcinoma. Number, size and distance from the main tumor of the tumor sprouting were observed and analyzed with clinicopathologic characteristics.

RESULTS

Tumor sprouting was observed in 101 patients. Presence of tumor sprouting was significantly associated with positive resection margin (p=.002), lymphovascular invasion (p=.001), lymph node metastasis (p<.001), and recurrence (p=.004). Univariate analysis of recurrence-free survival revealed that tumor multiplicity (p=.037), positive resection margin (p=.007), lymphovascular invasion (p=.004), lymph node metastasis (p<.001), and tumor sprouting (p=.004) were poor prognostic factors. In multivariate analysis, positive resection margin was an independent poor prognostic factor of recurrence.

CONCLUSIONS

In conclusion, tumor sprouting is significantly correlated with lymph node metastasis and recurrence. Evaluation of tumor sprouting in PTC patients could be helpful in predicting tumor recurrence or lymph node metastasis.

Diagnostic Whole-Body Scan May Not Be Necessary for Intermediate-Risk Patients with Differentiated Thyroid Cancer after Low-Dose (30 mCi) Radioactive Iodide Ablation

BACKGROUND

A diagnostic whole-body scan (WBS) is recommended 6 to 12 months after total thyroidectomy and radioactive iodide ablation in intermediate- or high-risk patients with differentiated thyroid cancer (DTC). The aim of this study was to evaluate the necessity of a diagnostic WBS after radioactive iodide ablation in intermediate-risk patients with DTC.

METHODS

A total of 438 subjects were included in the study: 183 low-risk subjects and 255 intermediate-risk subjects according to the American Thyroid Association guideline. All subjects diagnosed with DTC received 1,100 MBq (30 mCi) activity of radioiodine (I-131) following total thyroidectomy. On follow-up, all subjects underwent a diagnostic I-131 WBS after thyroid hormone withdrawal.

RESULTS

After initial radioactive iodide ablation, 95.1% of low-risk patients and 91.4% of intermediate-risk patients showed no uptake on diagnostic WBS (P=0.135). Intermediate-risk patients with stimulated thyroglobulin (Tg) levels higher than 2.0 ng/mL showed a greater rate of radioactive iodine uptake on diagnostic WBS. Four intermediate-risk patients showed recurrence during the 16 to 80 months follow-up period. Three of the four patients with recurrence showed no uptake on diagnostic WBS and had a stimulated Tg level less than 2.0 ng/mL.

CONCLUSION

A diagnostic I-131 WBS after radioactive iodide ablation in intermediate-risk patients with DTC may not be necessary. A large prospective study is necessary to determine the necessity of diagnostic WBS in intermediate-risk patients with DTC.

Prognostic factors in papillary microcarcinoma with emphasis on histologic subtyping: a clinicopathologic study of 148 cases

BACKGROUND

There continues to be controversy regarding which clinicopathological features confer a higher risk of adverse outcome in papillary microcarcinomas (PMC). The aim of this study was to assess the prognostic value of a meticulous histologic examination in PMC.

METHOD

All papillary thyroid carcinoma <1 cm in size without associated larger thyroid carcinomas, identified between 1977 and 2002, were categorized as PMC and subjected to a meticulous histopathologic examination by 2 thyroid pathologists.

RESULTS

148 PMC patients fulfilled the inclusion criteria. Within PMC, young age, male sex, tumor multicentricity, extrathyroidal extension, and infiltrative and larger tumor (≥0.5 cm) correlated with the presence of >1 cm metastatic node (MN) or >3 MN at presentation (p<0.05). With a median follow-up of 9.9 years, only 1 (0.7%) of 134 PMC patients died of thyroid carcinomas and 3 (2.2%) had recurrences in the neck. The patient who died had harbored a poorly differentiated carcinoma in his MN. The presence of MN and especially a large MN (>1 cm) correlated with worse recurrence-free survival (p=0.005 and p<0.0001, respectively). Except for one, all individuals with clinically adverse outcomes had >1 cm MN. Patients whose MNs were predominantly composed of poorly differentiated carcinoma or tall cell variant papillary thyroid carcinoma had a significant shorter recurrence-free survival (p<0.0001). Only 1 of 80 radioactive iodine-naïve PMC patients with absent or small MN (≤1 cm) had recurrence with a median follow-up of 9.2 years.

CONCLUSIONS

(i) The size and histotype of the MN are predictors of outcome in PMC and should be recorded. (ii) The very rare PMC patients who suffer recurrence or even die of disease have usually aggressive histopathologic features at presentation. (iii) PMC patients with nodal disease that is small or absent at presentation are at a very low risk of recurrence and may be spared radioactive iodine therapy.

Clinical impact of microscopic extrathyroidal extension in patients with papillary thyroid microcarcinoma treated with hemithyroidectomy

BACKGROUND

Pathologically confirmed microscopic extrathyroidal extension (ETE) is often identified after hemithyroidectomy in patients with papillary thyroid microcarcinoma (PTMC). Without the presence of microscopic ETE, these patients would be optimal candidates for hemithyroidectomy.

AIM

The present study aimed at evaluating the clinical impact of microscopic ETE on the recurrence of PTMC treated with hemithyroidectomy.

SUBJECTS AND METHODS

We compared the clinicopathological characteristics and 5-year outcomes for 262 PTMC patients without ETE and 86 with microscopic ETE who were treated with hemithyroidectomy between January 2004 and December 2010.

RESULTS

The mean tumour size was larger (0.67 vs. 0.54 cm, p < 0.001) and the proportion of tumours measuring ≥0.5 cm was higher (84.9 vs. 66.8 %, p = 0.001) in patients with microscopic ETE as compared with patients without ETE. Occult multifocal disease was more frequent in patients with microscopic ETE than in those without ETE (14.0 vs. 6.5 %, p = 0.030). However, the recurrence rate was not different between the two groups during the mean 55.8-month follow-up period. In addition, univariate and multivariate analyses revealed no meaningful association between recurrence and microscopic ETE in patients with PTMC treated with hemithyroidectomy.

CONCLUSIONS

Although microscopic ETE was associated with large tumour size and multifocal disease, its clinical impact on disease recurrence was not significant in PTMC patients treated with hemithyroidectomy. Therefore, microscopic ETE identified after hemithyroidectomy would not be an absolute indication for completion thyroidectomy in patients with PTMC.

Immune response in thyroid cancer: widening the boundaries

The association between thyroid cancer and thyroid inflammation has been repeatedly reported and highly debated in the literature. In fact, both molecular and epidemiological data suggest that these diseases are closely related and this association reinforces that the immune system is important for thyroid cancer progression. Innate immunity is the first line of defensive response. Unlike innate immune responses, adaptive responses are highly specific to the particular antigen that induced them. Both branches of the immune system may interact in antitumor immune response. Major effector cells of the immune system that directly target thyroid cancer cells include dendritic cells, macrophages, polymorphonuclear leukocytes, mast cells, and lymphocytes. A mixture of immune cells may infiltrate thyroid cancer microenvironment and the balance of protumor and antitumor activity of these cells may be associated with prognosis. Herein, we describe some evidences that immune response may be important for thyroid cancer progression and may help us identify more aggressive tumors, sparing the vast majority of patients from costly unnecessary invasive procedures. The future trend in thyroid cancer is an individualized therapy.

Papillary thyroid carcinoma nodal surgery directed by a preoperative radiographic map utilizing CT scan and ultrasound in all primary and reoperative patients

BACKGROUND

To study the diagnostic accuracy of physical examination (PE), ultrasonography (US), contrastenhanced computed tomography (CT) and in preoperative detection of macroscopic nodal metastasis in primary/recurrent papillary thyroid carcinoma (PTC) patients to determine if the routine addition of CT would be beneficial in accurate preoperative lymph-node surgery planning.

METHODS

In a tertiary center prospective study, 162 PTC patients underwent preoperative lymph-node evaluation by PE, US, and CT. Sensitivity, specificity, positive/negative predictive value (PPV/NPV) of each nodal detection technique were calculated in central/lateral cervical compartments. The gold standard for diagnostic-accuracy was surgical pathology.

RESULTS

In patients undergoing primary (Group I)/revision (Group II) surgical treatment for PTC, combined US/CT yielded significantly higher sensitivity for macroscopic lymph-node detection in both lateral and central neck, most marked in Group I-central compartment.

CONCLUSIONS

Combined preoperative US/CT provides reliable, objective, preoperative macroscopic nodal metastasis map to design rational nodal surgery in primary/revision PTC patients.

Radioactive iodine ablation does not prevent recurrences in patients with papillary thyroid microcarcinoma

OBJECTIVE

Although papillary thyroid microcarcinoma (PTMC) has a favourable long-term prognosis, disease recurrence after initial treatment remains a problem and controversy exists regarding the role of radioactive iodine (RAI) ablation in PTMC. We performed this study to evaluate the effect of RAI ablation on disease recurrence in patients with PTMC.

PATIENTS AND METHODS

Between 1994 and 2004, 2579 patients underwent thyroid surgery for thyroid cancer at Samsung Medical Center. Among these patients, 704 patients with PTMC presumed disease-free after initial treatment were followed up for disease recurrence (median, 64 months; range, 1-185 months). Patients with PTMC with microscopic extrathyroidal extension, cervical lymph node metastases or multifocality were considered to be in the intermediate-risk group for recurrence.

RESULTS

Disease recurrence was found in six patients at a median of 29 months (range, 10-70 months) after initial treatment; all six patients with recurrent tumours had received RAI treatment after total thyroidectomy. Disease-related mortality was not observed, even after recurrence. Based on a Cox regression model considering the standardized inverse probability of treatment weight (IPTW) within each propensity score stratum of patients with a similar likelihood of having received RAI ablation, the likelihood ratio for recurrence did not differ between the RAI ablation group and no RAI group (P = 0·17). When we performed a subgroup analysis considering only patients with PTMC at intermediate-risk for recurrence, RAI ablation again did not have a significant effect on recurrence (P = 0·79).

CONCLUSIONS

Radioactive iodine ablation after total thyroidectomy in low- and intermediate-risk patients with PTMC did not prevent recurrent tumours. Future randomized, controlled, multicenter prospective trials involving a larger sample of patients followed-up for a longer duration are warranted to confirm our findings.

Completion lobectomy and central compartment dissection in low-risk patients who had undergone less extensive surgery than hemithyroidectomy

Many low-risk patients with solitary papillary thyroid cancer located in one lobe had undergone surgery that was less extensive than hemithyroidectomy in China. An acceptable completion surgery regimen was suggested for these patients based on our experience. A total of 117 enrolled patients underwent completion surgery. Thirty-two patients had prior tumor resection, 46 patients had prior partial thyroidectomy and 39 patients had prior subtotal thyroidectomy. No neck dissection was performed. Reoperation was scheduled a median of 1.2 months (range, 3 days–6.5 months) after primary surgery for papillary thyroid cancer (PTC). Among the 117 patients, residual tumor was pathologically confirmed in 60 patients, with a residual rate of 51.28%. Among these 60 patients, residual tumor was identified in the thyroid bed alone in 18 patients and in compartment VI alone in 28 patients, while 14 patients exhibited residual tumor in both of these regions. Lymph node metastasis was observed in compartment VI in 42 patients (35.90%), and an average of 6.5 nodes were removed (range, 2–14 nodes for each patient). Additionally, 3.14 positive lymph nodes were removed on average from each of the 42 patients. We conclude that the completion regimen, including the ipsilateral residual lobe, the isthmus and ipsilateral compartment VI (prelaryngeal, pretracheal and paratracheal lymph nodes), is reasonable and acceptable for low-risk patients undergoing surgery that is less extensive than hemithyroidectomy.

The prognostic significance of nodal metastases from papillary thyroid carcinoma can be stratified based on the size and number of metastatic lymph nodes, as well as the presence of extranodal extension

BACKGROUND

Ultrasound and prophylactic dissections have facilitated identification of small-volume cervical lymph node (LN) metastases in patients with papillary thyroid carcinoma (PTC). Since most staging systems do not stratify risk based on size or number of LN metastases, even a single-microscopic LN metastasis can upstage a patient with low-risk papillary thyroid microcarcinoma (PMC) to an intermediate risk of recurrence in the American Thyroid Association (ATA) system and to an increased risk of death in the American Joint Committee on Cancer (AJCC) staging system (stage III if the metastatic node is in the central neck or stage IVA if the microscopic LN metastasis is identified in the lateral neck). Such microscopic upstaging may lead to potentially unnecessary or additional treatments and follow-up studies. The goal of this review is to determine if the literature supports the concept that specific characteristics (clinically apparent size, number, and extranodal extension) of LN metastases can be used to stratify the risk of recurrence in PTC.

SUMMARY

In patients with pathological proven cervical LN metastases (pathological N1 disease; pN1), the median risk of loco-regional LN recurrence varies markedly by clinical staging, with recurrence rates for patients who are initially clinically N0 (clinical N0 disease; cN0) of 2% (range 0%-9%) versus rates of recurrence for patients who are initially clinically N-positive (clinical N1 disease; cN1) of 22% (range 10%-42%). Furthermore, the median risk of recurrence in pN1 patients varies markedly by the number of positive nodes, <5 nodes (4%, range 3%-8%) vs. >5 nodes (19%, range 7%-21%). Additionally, the presence of extranodal extension was associated with a median risk of recurrence of 24% (range 15%-32%) and possibly a worse disease-specific survival.

CONCLUSION

Our previous paradigm assigned the same magnitude of risk for all patients with N1 disease. However, small-volume subclinical microscopic N1 disease clearly conveys a much smaller risk of recurrence than large-volume, macroscopic clinically apparent loco-regional metastases. Armed with this information, clinicians will be better able to tailor initial treatment and follow-up recommendations. Implications of N1 stratification for PTC into small-volume microscopic disease versus clinically apparent macroscopic disease importantly relate to issues of prophylactic neck dissection utility, need for pathologic nodal size description, and suggest potential modifications to the AJCC TNM (tumor, nodal disease, and distant metastasis) and ATA risk recurrence staging systems.

Epidermal growth factor receptor 1 expression is upregulated in undifferentiated thyroid carcinomas in humans

BACKGROUND

Epidermal growth factor receptor 1 (EGFR1) signaling is involved in human cancer cell progression and is responsible for aggressive biological behavior and poor clinical outcome in several human malignancies. Activation of the EGFR1 pathway has been proposed, among others, as being involved in the progression of thyroid cancer toward a thyroid-stimulating hormone (TSH)-independent phenotype. We have previously observed that undifferentiated thyroid carcinoma cells are hyper-sensitive to EGF signaling of downstream intracellular pathways, and this correlated both with the loss of TSH-dependency and increase in EGF-dependent proliferation and migration. Thus, we hypothesized that the upregulation of EGFR1 protein expression may be enhanced in parallel with transition toward a poorly differentiated phenotype in human thyroid carcinomas.

METHODS

The expression of EGFR1 was evaluated, by immunohistochemistry, in a series of 49 human thyroid carcinomas at different degrees of tumor differentiation.

RESULTS

The expression of EGFR1 protein was significantly upregulated in poorly differentiated and anaplastic thyroid carcinomas, whereas it was absent or faint in normal thyroid gland tissue and in differentiated thyroid papillary carcinomas. Of note, selected thyroid tumors characterized by a mixed population of differentiated and undifferentiated tumor cells, likely progressing from well to poorly differentiated and anaplastic phenotypes, exhibited EGFR1-negative differentiated fields together with EGFR1-positive poorly differentiated and anaplastic areas.

CONCLUSIONS

Upregulation of EGFR1 expression may be a molecular marker of dedifferentiation in thyroid epithelial carcinomas, likely being responsible for the activation of EGF signaling observed in tumor cells and favoring progression toward an angiogenic, poorly differentiated, TSH-independent phenotype.

Clinical aggressiveness of incidental and non-incidental thyroid cancer

BACKGROUND

With the increasing use of thyroid ultrasound, the recognition of thyroid nodules in a large proportion of apparently healthy subjects has become common. Because also the papillary thyroid microcarcinomas (PTMC) are being increasingly discovered, it is important to ascertain whether PTMC may exhibit heterogenous clinical features, associated with different aggressiveness.

AIM

We retrospectively examined 122 subjects [98 female (80.3%), and 24 male (19.7%)] with thyroid cancer to find potential clinical and pathological findings that could be predictive of clinically aggressive behavior.

RESULTS

Twenty of the 31 patients with true incidental cancer (64.5%) in comparison to 20 of the 91 patients with non-incidental cancer (21.9%) had a diameter <10 mm, and this difference was statistically significant (p<0.0001). There was a statistically significant association between size and invasiveness because 19.3% of invasive cancers were <10 mm whereas 44.6% of non-invasive cancers were <10 mm (p=0.005). The relationship between incidental discovery and invasiveness was also evaluated, but the proportion of incidental invasive cancer (19.3%) was not significantly different from that of incidental non-invasive cancer (30.8%). In the multivariate analysis, only size <10 mm (odds ratio=0.35, p=0.013) and papillary vs other histotypes (odds ratio=0.35, p=0.04) were statistically significant protective factors against invasiveness.

CONCLUSIONS

a) Incidentally discovered thyroid cancers are more frequently microcarcinomas; b) there appears to be no difference in terms of invasive behavior between incidental and non-incidental thyroid cancer; c) smaller tumor size emerges as a protective factor.

Serum thyrotropin as a risk factor for thyroid malignancy in euthyroid subjects with thyroid micronodule

BACKGROUND

An elevated thyroid stimulating hormone (TSH) level is a risk factor for differentiated thyroid cancer. The present study investigated whether TSH is a risk factor for thyroid microcarcinoma (TMC) in euthyroid subjects with a micronodule.

METHODS

In this cross-sectional study, 483 euthyroid subjects (77 males patients, 406 females patients) with a thyroid micronodule were enrolled and underwent ultrasound guided fine-needle aspiration biopsy. Serum TSH level was measured in every subject. The final diagnostic outcome (malignant or benign) was defined in conjunction with cytology and histology.

RESULTS

Compared with the patients below the population mean, patients above the population mean had a significantly higher malignancy rate (10.8% vs 4.8%, p = .025). Multiple logistic regression analysis revealed TSH as an independent risk factor for malignancy in euthyroid patients with a micronodule (odds ratio, 1.449; 95% confidence interval, 1.033-2.033; p = .031).

CONCLUSIONS

Measurement of TSH in subjects with a thyroid micronodule is helpful to estimate cancer risk.

Targeted treatment of differentiated and medullary thyroid cancer

The incidence of thyroid cancer is increasing, with a concomitant increase in the number of patients with advanced and metastatic disease. Discoveries regarding the pathogenesis of thyroid cancer have led to the recent development of new therapeutic agents that are beginning to appear on the market. Many of these new agents are targeted kinase inhibitors primarily affecting oncogenic kinases (BRAF V600E, RET/PTC) or signaling kinases (VEGFR, PDGFR). Some of these agents report significant partial response rates, while others attain stabilization of disease as their best response. Their impact on survival is unclear. While these agents target similar pathways, a wide variety of differences exist regarding efficacy and side effect profile. Current expert opinion advises that these agents be used only in a specific subset of patients.

Prognostic significance of ki-67 labeling index in papillary thyroid carcinoma

BACKGROUND

Ki-67 is a useful tool for evaluating cell proliferative activity in various tumors. Although the utility of Ki-67 labeling index (LI) to diagnose thyroid neoplasms has been investigated, little is known regarding the relationship between Ki-67 LI and the biological behavior of papillary thyroid carcinoma. In this study, we examined Ki-67 in 371 patients with papillary thyroid carcinoma to elucidate this issue.

METHODS

A total of 371 patients with papillary carcinoma who underwent initial and locally curative surgery between 1996 and 1997 were enrolled in this study. We immunohistochemically investigated Ki-67 LI in their primary lesions and compared this finding with various clinicopathological features, including patient prognosis.

RESULTS

Ki-67 LI was ≤1% in 213 patients (57%) and among the remaining 158, 35 showed Ki-67 LI >3%. Ki-67 LI was associated with patient age, massive extrathyroid extension, and distant metastasis at surgery. Of 363 patients without distant metastasis at surgery, 54 (15%) showed carcinoma recurrence during follow-up (average 124 months) and the disease-free survival (DFS) of patients with Ki-67 LI >1% was significantly worse than that of those with Ki-67 LI <1% (p < 0.0001). On multivariate analysis, Ki-67 LI was recognized as an independent prognostic factor for the DFS of patients. Although only eight patients died of carcinoma in our series, patients with Ki-67 LI >3% showed a significantly worse cause-specific survival (CSS) than those with Ki-67 LI <3% (p < 0.0001).

CONCLUSIONS

Careful evaluation of Ki-67 LI in primary lesions can predict DFS and CSS of patients with papillary thyroid carcinoma.

Differences in the Form of Presentation between Papillary Microcarcinomas and Papillary Carcinomas of Larger Size

Papillary thyroid carcinomas (PTCs) with a diameter ≤1 cm are referred to as papillary microcarcinomas (PTMCs). The prognostic factors for PTMCs have not been defined. Different clinical and histopathologic variables were studied in 152 PTCs, including 74 PTMCs and 78 PTCs of larger size. We found that PTMCs are associated with less multifocality (P = .046) and bilaterality (P = .003), fewer lymphadenectomies (P < .001), and a higher rate of incidental tumours (P < .001). Moreover, patients with a low aggressive profile were significantly older than the remaining patients (54 ± 13.7 years versus 45.8 ± 13.1 years; P = .001). In conclusion PTMCs show significant differences compared to PTCs of larger size in the form of presentation. Furthermore, it is possible that the classic risk factors, which are well validated in PTCs, such as age, must be cautiously interpreted in the current increasing subgroup of PTMCs.

Prognosis and management of invasive well-differentiated thyroid cancer

Invasive thyroid cancer is often asymptomatic and can take the surgeon and the patient by surprise. Maintenance of a high level of suspicion in patients who present with symptoms, an abnormal examination, recurrent disease, or documented metastatic disease lead the clinician to obtain appropriate cross-sectional imaging that helps to define the full extent of the disease. Specific guidelines are provided for the management of the various structures in the neck that are at risk for involvement by disease extension outside the gland or extracapsular extension outside a lymph node with involvement by metastatic disease. This article reviews the prognosis, diagnosis, management, and implications of invasive thyroid cancer affecting the various structures of the central and lateral compartments of the neck.

Visually discernible [18F]fluorodeoxyglucose uptake in papillary thyroid microcarcinoma: a potential new risk factor

CONTEXT

A significant number of papillary thyroid microcarcinomas (PTMCs), despite excellent prognosis, show aggressive features such as extrathyroidal extension (EE) and lymph node metastasis (LNM) that may not always be detected preoperatively or intraoperatively. The relapse rate appears also substantial.

OBJECTIVE

To assess the value of [(18)F]fluorodeoxyglucose (FDG) uptake in PTMC as a potential risk factor for preoperative risk stratification.

METHODS

This retrospective study included 87 patients (17 males and 70 females; mean age = 51.2 yr, range 29-74 yr) with a unifocal PTMC who underwent preoperative FDG-positron emission tomography (PET)/computed tomography (CT)and total thyroidectomy and central lymph node dissection. Statistical analyses were performed to compare the gender, age, tumor size, and FDG uptake in PTMC with the presence of histopathologically proven EE and central LNM (cLNM).

RESULTS

Of the 87 patients, 44 (51%) had EE, and 27 (31%) had cLNM. PET/CT showed visually discernible FDG uptake in 46 PTMCs (53%). FDG positivity of PTMCs was the only significant variable correlated with both EE and cLNM; there was a significant difference in the prevalence of both EE (70 vs. 29%) and cLNM (41 vs. 19.5%) between the FDG-positive and FDG-negative groups. In contrast, other already known risk factors, i.e. gender, age, and size, showed a correlation with only one or neither of EE and cLNM.

CONCLUSION

The results indicate that visual FDG positivity in PTMCs is a potential risk factor that can be useful for preoperative risk stratification. Prospective studies would be warranted to assess the long-term benefit and cost effectiveness of preoperative FDG-PET/CT.

Thyrotropin serum concentrations in patients with papillary thyroid microcancers

BACKGROUND

Recent studies have shown that elevated serum thyrotropin (thyroid-stimulating hormone [TSH]) concentrations are associated with an increased risk of differentiated thyroid cancers in patients with nodular goiter. Therefore, the measurement of TSH concentrations might support the clinical estimation of cancer risk, especially in patients with thyroid nodules that are too small for fine-needle aspiration biopsies. Thus, the objective of this study was to compare preoperative serum TSH concentrations in patients with papillary thyroid microcarcinoma (PTMC) and individuals in whom the presence of even small differentiated thyroid cancers was excluded by thorough histological examination of the thyroid after total thyroidectomy because of medullary thyroid carcinoma or c-cell hyperplasia.

METHODS

The study was a retrospective cross-sectional analysis. Thirty-three patients with PTMC who had undergone a hemi- or total thyroidectomy and 54 subjects with medullary thyroid carcinoma or c-cell hyperplasia in whom a total thyroidectomy had been performed between 1994 and 2008 were included. Exclusion criteria were the intake of medication that might affect thyroid function and previous thyroid cancer or thyroid surgery.

RESULTS

The mean TSH value was comparable between patients with PTMCs (1.40 +/- 0.92 mLU/L, 95% CI = 1.07-1.72) and the control group (1.43 +/- 1.44 mLU/L; 95% CI = 1.04-1.82, p = 0.912). There was a positive trend in correlation between nodule size and TSH levels in patients with PTMC (p = 0.066).

CONCLUSIONS

TSH is not elevated in subjects with PTMCs, indicating that it is not likely involved in the de novo oncogenesis of these small cancers. However, TSH might rather play a role in the progression of preexisting PTMCs.

Prognostic values of thyroid tumours

Thyroid cancer accounts for approximately 1% of total cancer cases in developed countries. The aim of this study has been to analyze the histopathological variants of thyroid tumours with regard to gender and age. Despite their relative rarity in our material, they exhibit a wide range of morphological patterns and biological behaviour. During the period from 2001-2007, 138 biopsy cases of thyroid tumours, which were fixed in buffered neutral formalin and embedded in paraffin, have been reviewed. Tissue sections (4microm thick) were cut and stained with hematoxylin and eosin (H&E). Follicular adenomas have been found in 39, 1% of cases, thyroid carcinomas in 60, 12%, whereas thyroid secondary carcinomas have been found in 0, 72% of cases. As far as histological variants of thyroid carcinomas are concerned, most frequently found were papillary carcinomas in 39,85% of cases; followed by follicular carcinomas in 9,42% of cases; follicular variants of papillary carcinomas in 5,79% of cases; medullary carcinomas in 3,62% of cases, while anaplastic and Hurthle cell carcinomas have been found in 0,72% of cases each. All histological variants of thyroid tumours occurred more frequently in women than in men. Papillary carcinoma has been found in 80% of female cases. Thyroid tumours in our material mainly occurred in the third, the fourth and the fifth decade of life. Our data indicate that apart from the fact that papillary carcinomas, well differentiated, and characterised by relatively good prognosis, were most frequent variants, certain morphological variants of it were associated with poor prognosis.

Increased incidence of papillary thyroid microcarcinoma with decreased tumor size of thyroid cancer

The prevalence of papillary thyroid microcarcinoma (PTMC) in thyroid cancer varies from 20.0% to 42.8% with a mean of 30.0%. Most of these patients have benign clinical courses and receive less aggressive therapeutic procedures in most medical centers. This study retrospectively reviewed 30 years data in one institute and compared it with recent publications to illustrate change in trends and influence of PTMC. Incidental PTMC is usually diagnosed as a postoperative microcarcinoma following thyroidectomy for presumably benign thyroid lesions. Subtotal thyroidectomy or lobectomy without radioactive iodide treatment is sufficient to treat incidental PTMC. In contrast, aggressive surgical treatment with (131)I therapy is indicated for non-incidental PTMC. Those with PTMC in the absence of extra-thyroid invasion diagnosed by postoperative permanent section received follow-up if they had initially received subtotal thyroidectomy. In long-term follow-up studies, cancer-specific mortality for PTMC ranged from 0% to 4%. Most of the mortality cases had distant metastasis at the time of surgery. The clinical course and therapeutic strategies for the non-incidental PTMC patients depend on the TNM stage at the time of diagnosis. One-third of PTMC with clinically aggressive behavior cannot be treated as indolent disease. Invasive tumor markers or larger tumor size are useful to predict tumor recurrence or distant metastasis for PTMC.

Well-differentiated thyroid carcinoma: comparison of microscopic and macroscopic disease

BACKGROUND

The rapid increase in the incidence of well-differentiated thyroid cancer in recent years is the result of smaller thyroid tumors (1 cm or less) being diagnosed more frequently. Few studies are available regarding the appropriate approach to this previously known postmortem incidental finding, and their results remain controversial.

METHODS

In 2005, our center started a registry of all patients with nonmedullary thyroid carcinoma who were followed at our institute. In the present study, data on the background, clinical, and outcome characteristics were collected from the registry for 225 patients with microscopic disease and 543 patients with macroscopic disease.

RESULTS

Patients with microscopic disease were slightly older (51 vs. 47.5 years, p = 0.003), had a higher female to male ratio (189:37 vs. 419:123; p = 0.06), and were affected more by papillary carcinoma (98.2% vs. 85.5%; p < 0.001). Multifocal disease was documented in 50.2% of the patients with microscopic disease and 46.8% of the patients with macroscopic disease (NS), and bilateral disease, in 42.6% and 36.8%, respectively (NS). Corresponding rates for the two groups for other tumor-related factors were as follows: lymph node involvement at initial treatment, 25.7% and 30% (NS); distant metastases, 2.4% and 5.1% (p = 0.16); persistent/recurrent disease, 11% and 32% (p < 0.001); and new distant metastases, 2.65% and 6.5% (p = 0.07). At a median follow-up of 5 years, 96% of the microscopic carcinoma group were disease free compared to 77% of the macroscopic group (p < 0.001).

CONCLUSION

The differences between patients with microscopic and macroscopic well-differentiated thyroid carcinoma may not justify a different therapeutic approach.

Identification of a neck lump as a lymph node metastasis from an occult contralateral papillary microcarcinoma of the thyroid: key role of thyroglobulin assay in the fine-needle aspirate

BACKGROUND

Thyroglobulin (Tg) assay of material from fine-needle aspiration of neck masses can help distinguish neck masses of thyroid origin from other masses. We describe its utility in a patient with an unusual constellation of findings, a neck lump identified as a lymph node metastasis from a contralateral occult papillary thyroid carcinoma (PTC).

SUMMARY

A 56-year-old woman was referred to our center for evaluation of a 15-mm right lateral cervical neck mass which was strongly hypoechoic, not homogenous and contained several microcalcifications. There was no family history of thyroid disease, the patient was euthyroid and was not taking medications for thyroid disorders. On physical examination the thyroid was slightly enlarged and was normal on ultrasound except for a 1 x 3 mm hypoechoic nodule in the middle of the left lobe. Ultrasound-guided fine-needle aspiration biopsy (FNAB) of the right lateral cervical mass was performed with the Tg concentration of the FNAB washout liquid being >300 ng/mL and the cytology showing lymphoid elements mixed with polymorphous epithelial cells with atypical nuclei, suggesting lymph node metastasis from a cancer of epithelial origin. A lymph node metastasis from a papillary thyroid microcarcinoma (micro-PTC) was the presumptive diagnosis with the preoperative staging being Tx N1b. The patient underwent total thyroidectomy and bilateral lymph node dissection. At pathology, the right cervical mass was confirmed as lymph node metastasis of a PTC, and a unifocal micro-PTC was found in the middle left lobe. The patient was readmitted for a therapeutic (131)I dose (4810 MBq). At the time of (131)I administration, the whole-body scan showed only minimal thyroid bed uptake and serum Tg was <1 ng/mL. She was maintained on l-thyroxine treatment (150 microg/d). Five year later she did not have evidence of recurrent or residual PTC.

CONCLUSIONS

We describe the first case of contralateral lymph node metastasis from a unifocal micro-PTC identified by the detection of high Tg levels in the wash-out liquid of FNAB.

An update on papillary microcarcinoma

PURPOSE OF REVIEW

There is a worldwide increasing incidence of thyroid cancer, mostly due to the increased diagnosis of papillary microcarcinoma (PMC). This review examines its clinical significance and optimal treatment.

RECENT FINDINGS

It is unclear whether or not the increase in PMC is real, or is simply due to the increased detection and diagnosis. The increase has been attributed to the widespread availability of thyroid ultrasound, with increasing numbers of clinically insignificant thyroid nodules subject to fine needle aspiration biopsy and surgical excision. An additional explanation is simply an increase in the number of routine histologic sections taken from the thyroidectomy specimens over the years. There have been two recent large clinical series with long-term follow-up highlighting the excellent prognosis of PMC. Novel research into immunohistochemical markers and advanced imaging with fluorodeoxyglucose positron emission tomography aims to identify the markers of more aggressive PMC. Management of PMC remains controversial, from observation alone to total thyroidectomy/radioiodine ablation.

SUMMARY

PMC has been increasing rapidly over recent decades due to increased cervical ultrasound and increased detection in pathological specimens. There is no compelling evidence base for the management of PMC, with retrospective series highlighting the excellent prognosis.

Lateral lymph node metastasis in papillary thyroid carcinoma: results of therapeutic lymph node dissection

BACKGROUND

Cervical lymph node metastases are quite common in papillary thyroid cancer (PTC) and they usually spread in a contiguous fashion. However, "skip metastasis," defined as lateral lymph node metastasis without central lymph node metastasis, also occurs in patients with PTC. There is little information regarding skip metastasis in papillary thyroid microcarcinoma (PTMC). The goal of this study was to determine the prevalence and associated clinical and imaging features of skip metastasis in PTMC.

METHODS

We performed a retrospective study of 245 patients with PTMC who underwent either thyroidectomy and central lymph node dissection or thyroidectomy, central lymph node dissection, and lateral lymph node dissection if preoperative ultrasonography or computed tomography suggested lateral node metastasis. Clinicopathologic results were reviewed, and the patterns of cervical lymph node metastasis were analyzed.

RESULTS

Cervical lymph node metastases were present in 26.5% of cases. The frequency of lymph node metastases was 21.8% in the group that only had thyroidectomy and central lymph node dissection and 51.3% in the group that had thyroidectomy, central lymph node dissection, and lateral lymph node dissection. Younger age, larger tumor size, multiplicity, bilaterality, encapsulation, extrathyroid extension, and lymphatic invasion were associated with metastasis to nodes in the central or lateral compartment. Lateral lymph node dissection was performed in 15.9% of patients. Skip metastasis was observed in 7.7% of the cases in which combined central and lateral node dissection was performed. No features of the primary thyroid tumor could be associated with the development of skip metastasis.

CONCLUSIONS

Skip metastases occur in a minority of patients with PTMC. We recommend, therefore, that preoperative studies in patients suspected of having PTMC focus not only on nodes in the central compartment but also lateral cervical nodes since the information obtained would guide the extent of surgery.

Incidence and histopathological behavior of papillary microcarcinomas: study of 429 cases

OBJECTIVE

We aim to present papillary microcarcinoma (PMC) incidence at a university teaching hospital, to compare characteristics of PMC in relation to size, and to assess for significant difference in PMC incidence among patients with non-PMC thyroid malignancies.

MATERIALS AND METHODS

Pathology results were reviewed for consecutive total thyroidectomies between 2002 and 2007 (n = 860). Statistical significance was calculated using chi(2) or, when unavailable, Fisher exact test.

RESULTS

PMC was found in 429 cases, which is 49.9 percent of all total thyroidectomies. In PMC > or =5 mm, 25.1 percent had extrathyroidal extension vs 9.1 percent for <5 mm (P < 0.001). When 4 mm is used as a threshold, P value was 300-fold smaller. Incidence in patients with any non-PMC thyroid malignancy was 51.6 percent against 47.2 percent in all other patients (P = 0.203).

CONCLUSIONS

In this study, PMC was found in 49.9 percent of patients, which, to our knowledge, is higher than any other reported incidence. A threshold of > or =4 mm was more significant than 5 mm for carrying increased risk for extrathyroidal spread. There was no significant difference in PMC incidence in patients with malignant vs benign disease.

Cervical masses as manifestation of papillary thyroid carcinomas </=10 mm in diameter, in patients with unknown thyroid disease

Background

Papillary thyroid microcarcinomas are tumors often found accidentally after thyroidectomy for other thyroid disorders.

Methods

Patients with enlarged lateral cervical masses, with unknown thyroid disease, found to have metastases from papillary thyroid carcinoma ≤10 mm in diameter, were compared to patients operated on for nodular or multinodular goiter, who were incidentally found to have papillary thyroid microcarcinomas.

Results

Group A included 24 patients with an enlarged lateral cervical mass whereas group B included 30 patients presenting with nodular or multinodular goiter. Patients in both groups underwent surgery. After thyroidectomy and lymph node dissection, pathology revealed multifocal papillary carcinomas of 1–10 mm, with invasion of the thyroid capsule and surrounding soft tissue in most of the cases in group A. Two patients presented with distant metastases at diagnosis which were surgically removed. During follow up, 3 patients (12.5%) presented with new cervical metastases which were surgically removed or treated with additional radioactive iodine. At last follow-up, all patients were alive. In contrast, all patients in group B had unifocal papillary thyroid carcinoma 1–10 mm in maximum diameter, with no infiltration or extension into the adjacent tissue, or cervical lymph node metastases.

Conclusion

Two groups of papillary thyroid microcarcinomas characterized by different clinical and biological behaviours are identified. Significant differences were found between these groups concerning the age, tumor size, number of tumor foci, lymph nodes metastases and extrathyroidal extension of the tumor. Papillary thyroid carcinomas of small (≤10 mm) size may have aggressive behaviour or be metastatic, and this subgroup should be treated and followed up as are other large, differentiated thyroid cancers.