Mortality rate and causes of death in papillary thyroid microcarcinoma

PURPOSE

Papillary thyroid microcarcinoma (PTMC) has an excellent prognosis; however, some PTMCs exhibit poor outcomes. Cancer-specific death from PTMC has been rarely reported, so we aimed to evaluate mortality rates and causes of death in patients who died with PTMC.

METHODS

We retrospectively reviewed 8969 PTMC patients treated at Samsung Medical Center from 1994 to 2017. Mortality rate and causes of death in PTMC patients were evaluated and compared with those of 7873 patients with papillary thyroid carcinoma (PTC) > 1 cm. In addition, we reviewed previous publications reporting cancer-specific deaths from PTMC.

RESULTS

Among the 8969 PTMC patients, 107 (1.2%) patients died. Only two (0.02%) patients have died of PTMC, which was less than the cancer-specific deaths from PTC > 1 cm (0.71%). Among the deceased PTMC patients, 63 (58.9%) died of other malignancies, three (2.8%) died of cardiovascular diseases, and five (4.7%) died of other diseases. Compared with PTC > 1 cm, cancer-specific deaths was less (1.9% vs. 15.1%, P < 0.001), and deaths from other malignancies were higher in deceased PTMC patients (58.9% vs. 30.5%, P < 0.001). According to 18 studies, PTMC-specific mortality rates ranged from 0.05% to 14.3%, and 336 cancer-specific deaths (0.43%) occurred among 78,770 PTMC patients.

CONCLUSION

The cancer-specific mortality rate of PTMC patients was extremely low (0.02%). More than half of deceased PTMC patients died of other malignancies, which was significantly more than those with PTC > 1 cm. These results support that active surveillance can be selected as a therapeutic option for PTMC.

Subcentimetric Papillary Thyroid Carcinoma: Does the Diagnosis Kind Impact Prognosis?

INTRODUCTION

Subcentimetric papillary thyroid carcinoma (SPTC) (papillary thyroid carcinoma with less than 10 mm in size) usually presents an excellent prognosis, with few aggressive reported cases. Given the globally increased incidence of SPTC, physicians are struggling with the need to identify prognostic factors to stratify SPTC. The aim was to compare clinicopathological variables and prognosis between clinically and incidentally diagnosed SPTC. Materials and methodsː This is a retrospective observational study on patients with SPTC who underwent thyroidectomy between 2002 and 2015. Two groups were considered: G1 (n=60 (61.9%)), clinical diagnosis (Bethesda III-VI cytology in the thyroid tumor/in cervical lymphadenopathies) and G2 (n=37 (38.1%)), incidental diagnosis (thyroidectomy for benign thyroid pathology). The histological material was reviewed, and molecular analysis of the BRAF, RAS, and TERT promoter (TERTp) genes was performed. Resultsː Ninety-seven individuals were included, 60 (61.9%) of which were from G1, with a predominance of female sex (n=83 (85.6%)). Individuals of G1 were younger (53.0±14.2 versus 59.3±13.9 years; p=0.035), were more frequently treated with 131-iodine (39.2% versus 13.4%; p=0.007), had the largest diameter (8 (p25-p75: 7-9) versus 5 (p25-p75: 4-6.5) mm; p<0.001), and higher frequency of minimal extracapsular invasion (45% versus 24.3%; p=0.041). Increased tumor size was the only independent predictor of a clinical diagnosis (p<0.001). Conclusionsː Clinically and incidentally diagnosed SPTC showed excellent medium- to long-term prognosis. A larger SPTC was more likely a driver of clinical detection than a marker of tumor aggressiveness, but caution should be taken as contradictory data persists.

Tumor border pattern and size help predict lymph node status in papillary microcarcinoma: A clinicopathologic study

OBJECTIVE

Lymph node metastasis occurs in a subset of papillary microcarcinoma patients. We aimed to analyze the differences between metastatic and non-metastatic papillary microcarcinomas in order to identify a high-risk subgroup that is likely to require more aggressive treatment.

MATERIALS AND METHODS

126 thyroidectomies with lymph node dissections (central ± lateral), diagnosed as papillary microcarcinoma, were reviewed.

RESULTS

Mean age of 126 patients (F/M = 3.3) was 42 years. Mean size of the largest tumor was 7 mm. Classical was the most frequently (89%) encountered subtype. Multiple histologic subtypes co-occurred in 19%. Lymphovascular invasion was present in 16% (n = 20). 55 (44%) and 71 (56%) cases were unifocal and multifocal, respectively. 90 cases (71%) were non-encapsulated with overall infiltrative tumor borders, whereas in 36 cases (29%), the tumor had a well-defined capsule. Among those, 23 (64%) had tumor capsule invasion. 47 (37%) cases had metastasis in lymph nodes. In univariate analysis, metastasis was associated with tumor size of >5 mm (p = 0.02), tumor burden of >5 mm (p = 0.03), lymphovascular invasion (p = 0.02) and non-encapsulation (p = 0.01). No associations were found regarding sex, age, histologic subtype, lymphocytic thyroiditis, tumor capsule invasion (in capsulated tumors), laterality and multifocality (p > 0.05). In multivariate analysis, lymphovascular invasion (p = 0.01, OR = 3.97, 95% CI 1.35-11.67), tumor size >0.5 cm (p = 0.031, OR = 2.92, 95% CI 1.10-7.71) and non-encapsulation (p = 0.033, OR = 2.85, 95% CI 1.08-7.51) were independent risk factors.

CONCLUSION

Size (largest tumor or sum of all foci) of >5 mm, non-encapsulation and lymphovascular invasion were independent predictors of LNM in PMs. Unifocal tumors metastasize the same as multifocal tumors, suggestive of the contribution of other factors. Patients with sporadically resected microcarcinomas should be carefully followed-up, especially those that harbor risk factors in histology.

Incidental versus clinical diagnosis of papillary thyroid microcarcinoma. Long-term prognosis

INTRODUCTION

The incidence of papillary thyroid microcarcinoma (PTMC) has increased in recent years, especially in patients operated on for presumably benign thyroid disease. The aim of this study was to analyze the differences between PTMC incidentally diagnosed and PTMC clinically diagnosed, as well as its long-term prognosis.

MATERIAL AND METHODS

The study population consisted of patients with a histological diagnosis of PTMC. Patients with previous thyroid surgery, other synchronous thyroid or extrathyroid malignancies and an ectopic location of PTMC were excluded. Two groups were compared: patients with PTMC incidentally diagnosed (group 1) and patients with PTMC clinically diagnosed (group 2). A multivariate analysis of differentiating factors was performed.

RESULTS

PTMC clinically diagnosed had a high frequency of hypothyroidism (4.6% vs. 18.9%; P=.004), extrathyroidal extension (5.7% vs. 17.6%; P=.018), metastatic lymph nodes (1.1% vs. 18.9%; P<.001) and lymphocytic thyroiditis (5.7% vs. 27%; P<.001). In the multivariate analysis, metastatic lymph nodes (OR: 22.011, IC 95%: 2.621-184.829; P=.004) and lymphocytic thyroiditis (OR: 4.949; IC 95%: 1.602-15.288; P=.005) were associated with the clinical diagnosis of PTMC. During a mean follow-up of 119.8±65.1 months, one recurrence was detected in group 2 (0% vs. 1,4%; P=.460). No patient died due to the disease.

CONCLUSIONS

PTMC clinically diagnosed, although it has more aggressive histopathological characteristics (extrathyroidal extension and metastatic lymph nodes), presents a long-term prognosis similar to the PTMC incidentally diagnosed. The presence of metastatic lymph nodes and lymphocytic thyroiditis were independent factors associated with PTMC clinically diagnosed.

Incidental and Non-incidental Papillary Thyroid Microcarcinoma in Denmark 1996-2015: A national study on incidence, outcome and thoughts on active surveillance

BACKGROUND

Incidental and non-incidental papillary microcarcinomas (PMC) are associated with different outcomes and treatment options may vary. The least favourable outcome is typically seen when carcinoma is suspected prior to surgery. Only a few studies have addressed the prognosis based on the way of detection for PMC, and they have been limited to retrospective single-center studies. We hypothesize that the "way of detection" may predict prognosis. The aim was to calculate the incidence and outcome of PMC based on the way of detection and to identify patients that may be suitable for active surveillance.

METHOD

This national cohort study consists of 803 patients diagnosed with PMC in Denmark from 1996 to 2015. Patients were identified from the DATHYRCA database and allocated into groups according to the way of detection leading to surgery: Incidental at surgery (n = 527), non-incidental with symptoms suspected from the index tumor (n = 134) and non-incidental with symptoms suspected from a metastasis (n = 142).

RESULTS

Age-standardized incidence rates increased from 0.35 per 100,000 per year in 1996 to 1.19 per 100,000 per year in 2015. A significant rise in incidence was found for both the incidental group and non-incidental group with symptoms suspected from a metastasis. Recurrence free survival was significantly worse for patients with suspicion of metastasis prior to surgery than patient groups without. No difference in mortality was found between groups.

CONCLUSION

PMC patients without suspicion of metastasis have the same low risk of recurrence as incidental cases and may be candidates for active surveillance.

The increasing prevalence of chronic lymphocytic thyroiditis in papillary microcarcinoma

Although the incidence of some malignancy has decreased over the recent years, this is not the case of papillary thyroid microcarcinoma (PTMC), whose incidence has increased worldwide. Most PTMC are found incidentally after histological examination of specimens from surgery for benign thyroid disease. Hashimoto's thyroiditis, whose incidence has also increased, coexists in about one in three PTMC patients. Three different mechanisms have been proposed to clarify the association between chronic lymphocytic thyroiditis and PTMC, namely tumor development/growth by: (i) TSH stimulation, (ii) expression of certain proto-oncogenes, (iii) chemokines and other molecules produced by the lymphocytic infiltrate. Whether Hashimoto's thyroiditis protects against lymph node metastasis is debated. Overall, autommune thyroiditis seems to contribute to the favorable prognosis of PTMC. Major limitations of the studies so far performed include: (i) retrospective design, (ii) limited statistical power, (iii) high risk of selection bias, (iv) and predominant Asian ethnicity of patients. Full genetic profiling of both diseases and identification of environmental factors capable to trigger them, as well as well-powered prospective studies on different ethnical groups, may help understand their causal association and why their frequencies are continuing raising.

Preoperatively undiagnosed papillary thyroid carcinoma in patients thyroidectomized for benign multinodular goiter

OBJECTIVE

Incidental thyroid cancers (ITCs) are often microcarcinomas; among them, the most frequent histotype is the papillary one. The purpose of this study was to evaluate the rate of papillary thyroid cancer (PTC) in patients thyroidectomized for benign multinodular goiter.

SUBJECT AND METHODS

We retrospectively evaluated the histological incidence of PTC in 207 consecutive patients who, in a 1-year period, underwent thyroidectomy for benign multinodular goiter. All patients came from an iodine-deficient area (Orleans, France) with three nuclear power stations located in the neighboring areas of the county town.

RESULTS

Overall, 25 thyroids (12.1%) harbored 37 PTC, of which 31 were microcarcinomas. In these 25 PTC patients, mean age was 55 ± 10 years (range 30-75), female:male ratio 20:5 (4:1). In 10 patients (40% of 25 and 4.8% of 207), PTCs were bilateral, and in 7 (2 with microPTCs) the thyroid capsule was infiltrated. These 7 patients underwent central and lateral cervical lymph node dissections, which revealed lymph node metastases in one and two cases, respectively. Radioiodine treatment was performed in 7 cases. Neither mortality nor transient and permanent nerve injuries were observed. Four (16%) transient hypocalcaemias occurred as early complications. At last follow-up visit (mean length of follow-up 17.2 ± 3.4 months), all patients were doing well and free of any clinical local recurrence or distant metastases.

CONCLUSION

With a 12% risk that multinodular goiter harbors preoperatively unsuspected PTCs, which can have already infiltrated the capsule and that can be accompanied by PTC foci contralaterally, an adequate surgical approach has to be considered.

Therapeutic Outcomes of Patients with Multifocal Papillary Thyroid Microcarcinomas and Larger Tumors

A retrospective review of 626 patients with multifocal papillary thyroid carcinoma (PTC) including 147 patients (23.5%) with multifocal papillary thyroid microcarcinoma (PTMC) from a total of 2,536 patients with PTC who visited the Chang Gung Medical Center in Linkou, Taiwan, was performed. A comparison of the clinical features between 626 multifocal and 1,910 solitary PTC cases showed that patients in the multifocal PTC group were older and had a smaller mean tumor size, a more advanced tumor-node-metastasis (TNM) stage, and a higher percentage of nonremission status compared to patients in the solitary PTC group. Of the 626 patients with multifocal PTC, the group with larger tumors showed a more advanced TNM stage, a higher percentage of lymph node metastasis and soft tissue invasion, and a higher nonremission rate compared to the multifocal PTMC group. Of the 626 patients with multifocal PTC, 25 patients (4%) died during a mean follow-up period of 7.1 ± 5.3 years. Kaplan-Meier survival curves showed a significantly lower survival rate associated with multifocal PTMC compared to that with solitary PTMC.

Differences in the Recurrence and Survival of Patients with Symptomatic and Asymptomatic Papillary Thyroid Carcinoma: An Observational Study of 11,265 Person-Years of Follow-Up

BACKGROUND

Papillary thyroid carcinoma (PTC) generally has an indolent course and favorable prognosis. However, an optimal treatment strategy for asymptomatic PTC is not clear. We compared the recurrence and survival outcomes of patients with asymptomatic and symptomatic PTC and identified the associated risk factors.

MATERIALS AND METHODS

Patients with previously untreated PTC of size ≤2 cm and who underwent curative surgery were included in this analysis. Asymptomatic PTC was defined as a tumor detected only by ultrasonography, computed tomography (CT), magnetic resonance imaging, and/or ¹⁸F-fluorodeoxyglucose positron emission tomography/CT. Clinical factors, operative and pathologic findings, and posttreatment outcomes were compared between the aforementioned two groups. Univariate and multivariate analyses were performed to identify the factors associated with recurrence-free survival (RFS) and overall survival (OS).

RESULTS

Out of 1419 patients, 1259 patients (88.7%) were asymptomatic. Patients with symptomatic PTC had significantly larger tumor size, palpability, extrathyroidal extension, high tumor and node stages, and were more likely to undergo treatment with radioactive iodine therapy compared with patients with asymptomatic PTC (p < 0.05 each). Recurrence was significantly higher in the symptomatic PTC group than in the asymptomatic group (p < 0.001). Asymptomatic PTC was an independent predictor of RFS and OS and had higher five-year rates than those associated with symptomatic tumors: 97.3% and 90.6% for RFS (p < 0.001) and 99.4% and 96.9% for OS (p < 0.001), respectively.

CONCLUSION

Symptomatic PTC is associated with higher recurrence and lower overall survival rates than asymptomatic PTC. Symptomatic PTC may require total thyroidectomy and close posttreatment surveillance.

Postoperative recurrence of papillary thyroid carcinoma with lymph node metastasis

BACKGROUND AND OBJECTIVES

The purpose of this study was to retrospectively analyze the features of patients with papillary thyroid carcinoma (PTC) presenting with neck lymph node (LN) metastasis.

METHODS

The study enrolled 909 patients with PTC who had undergone total thyroidectomy. After a median follow-up of 14.6 years, 73 (8.0%) patients died of thyroid cancer. A total of 536 patients had the tumor confined to the thyroid (intra-thyroid), 111 had lymph node (LN) metastasis, 225 showed soft tissue invasion, and 37 had distant metastasis.

RESULTS

Compared with the intra-thyroid group, the group with LN metastases showed larger tumor size, higher postoperative thyroglobulin levels, advanced TNM stage, higher recurrence rates (5.2% vs. 31.5%), and higher disease-specific mortality (1.3% vs. 12.6%). Of the 111 patients with PTC and LN metastases, 35 (31.5%) were diagnosed with recurrence during a mean follow-up period of 16.9 ± 0.6 years. Among the 35 patients with recurrent PTC, 14 (40.0%) died of thyroid cancer. The mortality group was characterized by older, mostly male patients who presented with larger initial tumor size compared with survivors.

CONCLUSIONS

In patients with PTC, the rates of recurrence and cancer mortality were higher in the group with LN metastasis than that in the intra-thyroid tumor group.

Differences in the recurrence and mortality outcomes rates of incidental and nonincidental papillary thyroid microcarcinoma: a systematic review and meta-analysis of 21 329 person-years of follow-up

CONTEXT

There is controversy as to whether papillary thyroid microcarcinoma (PTMC) represents more than one disease entity with different outcomes, requiring different treatment.

OBJECTIVES

To compare characteristics, outcomes, and factors associated with prognosis of incidental and nonincidental PTMC.

SETTING AND DESIGN

Two reviewers performed searches of online databases (1966-2012), reference lists, and conference abstract books. Longitudinal studies of subjects >16 years old receiving any treatments for papillary thyroid cancer ≤10 mm in size were included. Two reviewers independently screened abstracts and articles, extracted data, and assessed quality of studies using National Institute of Clinical Excellence and PRISMA criteria.

RESULTS

Of 1102 abstracts identified, 262 studies were reviewed and 17 studies included, comprising 3523 subjects, with mean follow-up of 70 months and total follow-up of 21 329 person-years. This included 854 subjects with incidental PTMC (follow-up, 4800 person-years; mean tumor size, 4.6 mm [range 3.3-6.7 mm]) and 2669 nonincidental PTMC cases (follow-up, 16 529 person-years; mean tumor size, 6.9 mm [range 5.6-8.0 mm]). The recurrence rate in the incidental group (0.5%; 95% confidence interval [CI], 0-1%, P < .001) was significantly lower than that in the nonincidental group PTMC (7.9%; 95% CI, 5-11%), with an OR of recurrence of 14.7 (95% CI, 5.6-54.8, P < .001) for nonincidental PTMC, compared with incidental PTMC. Lymph nodes were involved in 80% (126/157) of recurrences. On meta-regression, age, sex, size, tumor multifocality, lymph node involvement, and treatment modality were not significantly associated with recurrence.

CONCLUSIONS

Our meta-analysis strongly suggests the existence of at least two distinct entities of PTMC. Incidental PTMC has different clinical characteristics and a much lower recurrence rate than nonincidental PTMC, suggesting that management protocols should be re-considered. Additional studies with standardized data collection are required to explore potential differences between subgroups of nonincidental PTMC.

Current controversies in the initial post-surgical radioactive iodine therapy for thyroid cancer: a narrative review

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy and the fifth most common cancer in women. DTC therapy requires a multimodal approach, including surgery, which is beyond the scope of this paper. However, for over 50 years, the post-operative management of the DTC post-thyroidectomy patient has included radioactive iodine (RAI) ablation and/or therapy. Before 2000, a typical RAI post-operative dose recommendation was 100 mCi for remnant ablation, 150 mCi for locoregional nodal disease, and 175-200 mCi for distant metastases. Recent recommendations have been made to decrease the dose in order to limit the perceived adverse effects of RAI including salivary gland dysfunction and inducing secondary primary malignancies. A significant controversy has thus arisen regarding the use of RAI, particularly in the management of the low-risk DTC patient. This debate includes the definition of the low-risk patient, RAI dose selection, and whether or not RAI is needed in all patients. To allow the reader to form an opinion regarding post-operative RAI therapy in DTC, a literature review of the risks and benefits is presented.

Papillary thyroid microcarcinoma in Denmark 1996-2008: a national study of epidemiology and clinical significance

BACKGROUND

With an observed general rise in papillary thyroid carcinoma incidence, papillary microcarcinoma (PMC) is accordingly found more frequently and often incidentally by histological examination of surgical specimens from presumed benign thyroid disease. Only a few studies have specifically addressed the prognosis of incidentally found PMC, and they have been limited to retrospective single-center studies.

METHODS

This was a national, unselected, prospective cohort study of 406 papillary thyroid microcarcinoma patients diagnosed in Denmark from 1996 to 2008.

OBJECTIVE

The aim of this study was to evaluate incidence, outcome, and extent of necessary treatment, with special attention given to incidentally detected PMC.

RESULTS

Age-standardized ratios were found to increase from 0.35 per 100,000 per year in 1996 to 0.74 per 100,000 per year in 2008. A total of 240 out of 406 cases were found incidentally, and a significant rise in incidence was only found for the incidental cases. Median follow-up was 7.6 years for the incidental cases, and in this time span, five cases of recurrence and no deaths from thyroid cancer occurred. The five-year recurrence-free survival was 98.1%, and only occurrence of lymph-node metastasis was found to affect the recurrence rate. A total of 160 incidental cases were initially treated with lobectomy, and the incidence of recurrence was not significantly different in the cases receiving completion thyroidectomy.

CONCLUSION

The rising incidence of PMC in Denmark is explained by incidental cases. When the carcinoma is not the index tumor for surgery, this study implies that completion thyroidectomy does not improve prognosis.

Clinical and pathological characteristics of incidental and nonincidental papillary thyroid microcarcinoma in 339 patients

BACKGROUND

We analyzed the incidence and the clinicopathological characteristics of papillary thyroid microcarcinoma (PTMC) in a high prevalence region of goiter with the purpose to investigate differences between incidental and nonincidental PTMC.

METHODS

A total of 2236 patients who underwent total thyroidectomy from 2001 to 2009 were reviewed retrospectively. Papillary carcinoma was diagnosed in 583 patients. Of these, 339 patients with PTMC were included in the study. Clinicopathological features were evaluated by univariate and multivariate analysis.

RESULTS

The prevalence of incidental PTMC was 12% of all patients who underwent surgery for thyroid disease. Univariate analysis showed that bilaterality (p = .001), autoimmune thyroid disease (p = .049), size of tumor >5 mm (p < .001), multifocality (p < .001), lymph node metastasis (p < .001), and capsule invasion (p < .001) were significantly associated with nonincidental PTMC. The incidence of lymph node metastasis in incidental PTMC was 5% versus 33% in nonincidental, suggesting that the biological behavior may be different in the 2 categories.

CONCLUSION

Our results indicate that a high rate of PTMC presented 1 or more risk factors including multifocality, bilaterality, capsule invasion, and lymph node metastasis. Therefore, we suggest total thyroidectomy followed by adequate exploration of the central neck compartment for possible nodal involvement and resection as a safe therapeutic approach.

Comparative study of thyroid puncture biopsy guided by contrast-enhanced ultrasonography and conventional ultrasound

The aim of this study was to investigate the application value of thyroid puncture biopsy guided by contrast-enhanced ultrasound (CEUS). A total of 48 patients with 51 solid thyroid nodules (suspected papillary thyroid carcinoma, PTC) were enrolled in the study. Following detection by conventional ultrasonography and CEUS, puncture biopsy of the suspicious lesions guided by conventional ultrasonography and CEUS was conducted, respectively. Then, pathological diagnosis was performed. The number of PTC positive nodules and puncture points detected by the two methods were compared. In 51 nodules with 310 punctures, 44 nodules (86.3%, 44/51) and 240 punctures (77.4%, 240/310) were pathologically diagnosed as PTC. In the 44 nodules diagnosed as PTC, 43 and 34 nodules were detected by CEUS and conventional ultrasound, respectively, with a significant difference between the two methods (P=0.022). Eleven (25%) nodules were independently detected by CEUS. The sensitivity and accuracy of puncture point detection by CEUS (82.9 and 82.6%, respectively) were significantly higher compared with those of conventional ultra-sound (48.3 and 56.5%, respectively; P<0.001). The specificity of puncture points detected by CEUS (81.4%) was significantly lower compared with that by conventional ultrasound (84.3%; P=0.009). Compared with conventional ultrasound, a greater number of PTC-positive nodules were detected by CEUS, with increased sensitivity and accuracy of the puncture points.

Incidental versus clinically evident thyroid cancer: a 5-year follow-up study

BACKGROUND

The incidence of differentiated thyroid cancer in patients undergoing surgery for presumed benign thyroid disease (incidental thyroid cancer) is not negligible. The purpose of this study was to verify if incidental thyroid cancers have a different clinical course than the clinically evident thyroid cancer.

METHODS

A group of patients with incidental thyroid cancer (n = 95) has been compared to a control group with clinically evident thyroid cancer (n = 93). Both the histology and the outcome after a 5-year follow-up have been compared.

RESULTS

At the univariate analysis, the groups demonstrated significant differences in many pathologic features, remnant ablation (p < .001), and persistent disease (p = .006). Nevertheless, the multivariate analysis revealed that the outcome was not influenced by the preoperative or the incidental diagnosis.

CONCLUSION

Incidental thyroid cancers show a different pathological pattern when compared to clinically evident thyroid cancers. Nonetheless, the final outcome is not influenced by preoperative or postoperative diagnosis. Hence, patients with incidental thyroid cancer should follow the same postoperative protocols of patients with clinically evident thyroid cancer.

Managing thyroid microcarcinomas

Papillary thyroid microcarcinomas (PTMCs) are the most common form of classic papillary thyroid carcinoma (PTC). PTMCs are typically discovered by fine-needle- aspiration biopsy (FNAB), usually with sensitive imaging studies, or are found during thyroid surgery in a patient without a previously known history of thyroid carcinoma. However, the definition of PTMC has not always been universally accepted, thus creating controversy concerning the diagnosis and treatment of PTMC. The aim of this review is to summarize the clinical features of PTMC and identify the widely differing opinions concerning the diagnosis and management of these small ubiquitous thyroid tumors.

Prognostic evaluation of patients with multicentric papillary thyroid microcarcinoma

BACKGROUND/PURPOSE

Patients with papillary thyroid microcarcinoma (PTMC) often have an excellent prognosis. We hypothesize that patients with multicentric PTMC are associated with good clinical outcome, although multicentricity in papillary thyroid carcinoma may be associated with poor prognosis.

METHODS

Retrospective analysis of multicentric PTMC cases in one medical center enrolled from 1987 to 2008 was conducted. At the end of follow-up, patients were classified as "recurrence-free" or "recurrence or persistent disease". The tumor-node-metastasis (TNM) staging system was used, and (T1, N0, M0) was regarded as "early clinical stage", whereas (T3-4, any N, any M) or (any T, N1, or M1) was regarded as "advanced clinical stage".

RESULTS

There were 61 patients with a median age of 45 years. After a median follow-up period of 7.3 years (range: 2.1-22.1 years), the overall cause-specific survival rate was 98.36%. The patients with tumor diameters < 0.5 cm were all recurrence-free. Advanced clinical stage, especially distant metastasis, was highly associated with recurrence or persistent disease.

CONCLUSION

Our results demonstrate excellent prognosis in multicentric PTMC patients. No patients with tumor diameter < 0.5 cm had recurrence or persistent disease. Tumor size is an important risk factor in patients with multicentric PTMC.

Predictors of malignancy in patients with cytologically suspicious thyroid nodules

BACKGROUND

Fine needle aspiration (FNA), although very reliable for cytologically benign and malignant thyroid nodules, has much lower predictive value in the case of suspicious or indeterminate nodules. We aimed to identify clinical predictors of malignancy in the subset of patients with suspicious FNA cytology.

METHODS

We reviewed the electronic medical records of 462 patients who had FNA of thyroid nodules at our institution with a suspicious cytological diagnosis, and underwent surgery at Mayo Clinic between January 2004 and September 2008. Demographic data including age, gender, history of exposure to radiation and use of thyroid hormone was collected. The presence of single versus multiple nodules by ultrasonography, nodule size, and serum thyroid-stimulating harmone (TSH) level before thyroid surgery were recorded. Analysis of the latter was limited to patients not taking thyroid hormone or antithyroid drugs at the time of FNA.

RESULTS

Of the 462 patients, 327 had lesions suspicious for follicular neoplasm (S-FN) or Hürthle cell neoplasm (S-HCN), 125 had cytology suspicious for papillary carcinoma (S-PC) and 10 had a variety of other suspicious lesions (medullary cancer, lymphoma and atypical). Malignancy rate for suspicious neoplastic lesions (FN+HCN) was ∼15%, whereas malignancy rate for lesions S-PC was 77%. Neither age, serum TSH level, or history of radiation exposure were associated with increased malignancy risk. The presence of multiple nodules (41.1% vs. 26.4%, p=0.0014) or smaller nodule size (2.6±1.8 cm vs. 2.9±1.6 cm, p=0.008) was associated with higher malignancy risk. In patients with cytology suspicious for neoplasm (FN, HCN) malignancy risk was higher in those receiving thyroid hormone therapy than in nonthyroid hormone users (37.7% vs. 16.5%, p=0.0004; odds ratio: 3.1), although serum TSH values did not differ significantly between thyroid hormone users and nonusers.

CONCLUSION

In patients with cytologically suspicious thyroid nodules, the presence of multiple nodules or smaller nodule size was associated with increased risk of malignancy. In addition, our study demonstrates for the first time, an increased risk of malignancy in patients with nodules suspicious for neoplasm who are taking thyroid hormone therapy. The reason for this association is unknown.

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.

Papillary thyroid microcarcinoma: extrathyroidal extension, lymph node metastases, and risk factors for recurrence in a high prevalence of goiter area

BACKGROUND

Although papillary thyroid microcarcinoma (PTMC) is diagnosed with increasing frequency, the best therapeutic option and follow-up protocol have not been established yet, especially in the case of incidental diagnosis. We reviewed our series of patients with PTMC to determine risk factors for recurrence in an area where there is a high prevalence of goiter.

METHODS

The medical records of all patients who underwent thyroidectomy with a final pathology report of PTMC between October 2002 and June 2007 were reviewed. PTMC was defined as a papillary thyroid carcinoma 10 mm or less in diameter. Follow-up evaluation was obtained by outpatient consultation and/or telephone interview.

RESULTS

In a series of 2,220 patients who underwent thyroidectomy for a thyroid carcinoma, 933 had a PTMC. Diagnosis was incidental in 704 patients (75.5%). Upon multivariate analysis, tumor size, nonincidental diagnosis, and neck node metastases at diagnosis were independent risk factors for extracapsular spread (ECS), while ECS, multifocal disease, and number of removed lymph nodes were independent risk factors for lymph node metastases at diagnosis. Follow-up evaluation was completed in 287 patients, 9 (3.1%) of whom experienced recurrence. The number of removed and metastasized nodes at first operation and the length of the follow-up were independent risk factors for recurrent disease.

CONCLUSIONS

Incidental diagnosis of PTMC is frequent in a high prevalence of goiter area. PTMC shows a variable degree of aggressiveness. Management protocols should be based on patient- and tumor-related prognostic factors, as for larger tumors.

Are Papillary Microcarcinomas of the Thyroid Gland Revealed by Cervical Adenopathy More Aggressive?

Therapeutic attitudes for papillary thyroid microcarcinoma (PTMC) range from observation alone to aggressive management. Clinicopathologic features, therapeutic options, and follow-up results are described in a series of PTMC revealed by cervical adenopathies. Twelve patients were enrolled in this retrospective study. They were all treated by total/near-total thyroidectomy with dissection of suspect cervical lymph nodes followed by radioactive iodine (RAI) and suppressive L-thyroxine therapies. Mean age at diagnosis was 32 years with a mean elapsed time to diagnosis of 45.3 months. Fine needle aspiration cytology and excisional biopsy of the lymph node led to a diagnosis in all cases. Cervical mass was ipsilateral to primary tumor in six patients (50%). Multifocality, bilaterality, and capsular invasion were encountered in 66.7, 66.7, and 41.7 per cent of patients, respectively. Lymph node involvement was bilateral in seven patients (58.3%) of whom thyroid foci were unilateral in two. No complications of thyroidectomy were encountered. At 60-month-follow up, no recurrence or metastasis was noted. PTMC revealed by cervical lymph node metastasis shows aggressive clinicopathologic features. They must be considered as papillary thyroid cancers and managed by total/near-total thyroidectomy with bilateral lymph node exploration followed by RAI therapy and suppressive L-thyroxine doses.

Incidental papillary carcinoma in patients treated surgically for benign thyroid diseases

BACKGROUND

The frequency of incidental papillary carcinoma (IPC) has been reported to be between 4.6 % and 10% in operatively treated benign thyroid diseases. This study reviews the occurrence of IPC in thyroid glands removed for benign disease at our institution.

METHODS

Six hundred and seventy-eight patients underwent partial or total thyroidectomy for benign thyroid diseases. The incidence of IPC was compared among patients with Hashimoto's thyroiditis, multinodular goiter, follicular adenoma, and Graves' disease.

RESULTS

Overall, 81 (12.0%) IPCs were recorded with decreasing order of frequency: Hashimoto's thyroiditis, follicular adenoma, goiter, and Graves' disease. Contralateral IPC was detected in 6/15 (40%) patients with follicular adenoma.

CONCLUSION

The overall incidence of IPC in benign operatively resected thyroid disease was 12%. Hashimoto's thyroiditis had the greatest rate of IPC. IPC was encountered in the contralateral lobe in 40% of patients with follicular adenoma. The association of IPCs with Hashimoto's thyroiditis may indicate a link to thyroid cancer. Total thyroidectomy may be considered an appropriate operative treatment in patients with Hashimoto's thyroiditis and follicular adenoma requiring operation owing to the high incidence and frequent contralateral involvement of IPC, respectively.

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.

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.