Isthmic Papillary Thyroid Carcinoma Presents a Unique Pattern of Central Lymph Node Metastasis

The use of thyroid isthmusectomy for management of well differentiated thyroid carcinoma - A systematic review and meta-analysis

OBJECTIVE

With the growing global incidence of thyroid carcinomas, there is an increasing need for distinct guidelines for isthmus-confined carcinomas. Here, we performed the first systematic review on the topic to date, aiming to provide understanding to isthmusectomy as surgical management for well-differentiated thyroid carcinoma of the isthmus.

METHODS

We conducted a systematic review following the PRISMA guidelines, analyzing English-language studies from the past decade that report on thyroid isthmusectomy. Exclusion criteria included isthmusectomy performed alongside full thyroidectomy or partial thyroid lobectomy, lack of data on tumor characteristics or survival outcomes, and non-English publications where a translation was unavailable. Our review identified a total of 227 patients from seven studies.

RESULTS

The average 5-year overall survival and disease-free survival rates for patients with isthmus-confined PTC who underwent isthmusectomy were 100 % and 93.1 %, respectively. Similar to that of total thyroidectomy. 3.1 % of patients required completion thyroidectomy. Furthermore, isthmusectomy resulted in fewer surgical complications than total thyroidectomy.

CONCLUSIONS

The scarcity of studies providing detailed tumor characteristics and patient outcomes limits our ability to fully evaluate the safety and efficacy of isthmusectomy for isthmus-confined PTC. Additionally, the variable sample sizes and restricted geographic distribution of the included studies calls into questions the generalizability of their findings. Despite these limitations, the data suggest that isthmusectomy may be a viable surgical option for select patients with small, isthmus-confined PTC. In the absence of a randomized controlled trial on the noninferiority of isthmusectomy, significantly more publications are needed before strong conclusions can be drawn.

Molecular characteristics of isthmus papillary thyroid cancers: Supporting evidence for unfavorable clinical behavior

BACKGROUND

Previous studies demonstrate isthmus thyroid nodules are more likely to be malignant than lobar nodules. Additional data suggest that isthmus papillary thyroid cancers (PTCs) are more aggressive than lobar PTCs. We hypothesize that isthmus PTCs have a more unfavorable molecular profile.

METHODS

The Cancer Genome Atlas (TCGA) database was queried to analyze clinical, mutation and gene expression data of isthmus PTCs compared to non-isthmus PTCs.

RESULTS

We analyzed characteristics of 472 ​PTCs, including 19 isthmus PTCs. There were no significant differences between isthmus and non-isthmus PTC demographic and clinical variables or the frequency of RAS family, fusion driver, TERT, and tumor suppressor gene mutations. There was a trend towards increased BRAF mutations (68% vs 55%, p ​= ​0.28). A more aggressive gene expression profile was observed in isthmus PTC compared to lobar/multifocal PTC with differences in ERK score (19.4 vs 7.71, p ​< ​0.05) and TDS score (-0.58 vs 0.02, p ​< ​0.05).

CONCLUSIONS

These results provide a possible molecular explanation for the more aggressive behavior reported in isthmus PTCs.

Development and validation of nomograms for predicting the risk of central lymph node metastasis of solitary papillary thyroid carcinoma of the isthmus

BACKGROUND

This study was conducted to develop nomograms and validate them by assessing risk factors for the development of central lymph node metastasis (CLNM) in patients with solitary papillary thyroid carcinoma of the isthmus (PTCI) for predicting the probability of CLNM.

METHODS

Demographic and clinicopathological variables of patients with solitary papillary thyroid carcinoma (PTC) from May 2018 to May 2023 at the First Hospital of Shanxi Medical University were retrospectively analyzed, and the lobar group and the isthmus group were divided according to tumor location. Patients with the same sex, age difference of less than 3 years, and equal gross tumor diameter were selected from the lobar group and compared with the paraisthmic tumor group. Independent risk factors were determined using univariate and multivariate logistic regression analysis. On this basis, clinical predictive nomograms were developed and validated.

RESULTS

Clinical data from 326 patients with solitary PTCI and 660 cases of solitary lobar PTC were used for analysis in our study. The incidence of solitary tumors CLNM located in the median isthmus, paracentral isthmus, and lobes was 69.8%, 40.9%, and 33.6%, respectively. Statistical analysis revealed that gender, age, isthmus location, maximum nodal diameter, the presence of possible CLNM in advance on preoperative ultrasound, chronic lymphocytic thyroiditis, and the lymphocyte/monocyte ratio were independent risk factors for preoperative CLNM in patients with solitary PTCI. Age, isthmus location, chronic lymphocytic thyroiditis, gross tumor diameter, presence of intraoperative extrathyroidal extension, and presence of metastasis in the Delphian lymph node on frozen section were independent risk factors for intraoperative CLNM. The concordance indices of nomograms for preoperative and intraoperative are 0.871 and 0.894 in the training set and 0.796 and 0.851 in the validation set, calibration curve and decision curve analysis also demonstrated the strong reliability and clinical applicability of this clinical prediction model.

CONCLUSION

In this study, we concluded that solitary PTCI is more aggressive compared to solitary lobar PTC, and we constructed nomograms and risk stratification to accurately identify patients with solitary PTCI who are at high risk of developing CLNM, which will help clinicians in personalized decision making.

Machine learning-based dynamic prediction of lateral lymph node metastasis in patients with papillary thyroid cancer

OBJECTIVE

To develop a web-based machine learning server to predict lateral lymph node metastasis (LLNM) in papillary thyroid cancer (PTC) patients.

METHODS

Clinical data for PTC patients who underwent primary thyroidectomy at our hospital between January 2015 and December 2020, with pathologically confirmed presence or absence of any LLNM finding, were retrospectively reviewed. We built all models from a training set (80%) and assessed them in a test set (20%), using algorithms including decision tree, XGBoost, random forest, support vector machine, neural network, and K-nearest neighbor algorithm. Their performance was measured against a previously established nomogram using area under the receiver operating characteristic curve (AUC), decision curve analysis (DCA), precision, recall, accuracy, F1 score, specificity, and sensitivity. Interpretable machine learning was used for identifying potential relationships between variables and LLNM, and a web-based tool was created for use by clinicians.

RESULTS

A total of 1135 (62.53%) out of 1815 PTC patients enrolled in this study experienced LLNM episodes. In predicting LLNM, the best algorithm was random forest. In determining feature importance, the AUC reached 0.80, with an accuracy of 0.74, sensitivity of 0.89, and F1 score of 0.81. In addition, DCA showed that random forest held a higher clinical net benefit. Random forest identified tumor size, lymph node microcalcification, age, lymph node size, and tumor location as the most influentials in predicting LLNM. And the website tool is freely accessible at http://43.138.62.202/.

CONCLUSION

The results showed that machine learning can be used to enable accurate prediction for LLNM in PTC patients, and that the web tool allowed for LLNM risk assessment at the individual level.

Risk Factors and Prediction Model for Lateral Lymph Node Metastasis of Papillary Thyroid Carcinoma in Children and Adolescents

Purpose

Papillary thyroid carcinoma (PTC) in children and adolescents is prone to lateral lymph node metastasis (LNM), which is a high-risk factor for recurrence. However, few studies focused on identifying risk factors and establishing prediction models for lateral LNM of PTC in children and adolescents.

Patients and Methods

We retrospectively reviewed consecutive cases of children and adolescents with PTC undergoing thyroidectomy and cervical lymph node dissection between January 2009 and December 2019. The demographics and clinicopathologic features were collected and analyzed.

Results

A total of 102 children and adolescents with PTC were enrolled in our study; 51 of whom had lateral LNM (50%). After adjusting for other risk factors, the independent risk factors for lateral LNM were multifocality (odds ratio [OR]: 6.04; 95% confidence interval [CI]: 1.653–22.092; p=0.007), tumor size (OR: 1.752; 95% CI: 1.043–2.945; p=0.034), and the number of central LNM (OR: 1.23; 95% CI: 1.028–1.472; p=0.023). The formula of the combined predictor is: Multifocality + 0.31 × Tumor size + 0.115 × Number of central LNM. The area under the receiver operating characteristic curve of multifocality, tumor size, number of central LNM, and the combined predictor was 0.706, 0.762, 0.748, and 0.855, respectively. When the value of the combined predictor was ≥2.2744, lateral LNM could be predicted. The sensitivity and specificity of the predicted value were 82.4% and 74.5%, respectively.

Conclusion

The independent risk factors for lateral LNM in children and adolescents with PTC were multifocality, tumor size, and the number of central LNM. The prediction model can better predict the presence of lateral LNM.