Utility of Routine Frozen Section of Thyroid Nodules Classified as Follicular Neoplasm

A study of machine learning models for rapid intraoperative diagnosis of thyroid nodules for clinical practice in China

BACKGROUND

In China, rapid intraoperative diagnosis of frozen sections of thyroid nodules is used to guide surgery. However, the lack of subspecialty pathologists and delayed diagnoses are challenges in clinical treatment. This study aimed to develop novel diagnostic approaches to increase diagnostic effectiveness.

METHODS

Artificial intelligence and machine learning techniques were used to automatically diagnose histopathological slides. AI-based models were trained with annotations and selected as efficientnetV2-b0 from multi-set experiments.

RESULTS

On 191 test slides, the proposed method predicted benign and malignant categories with a sensitivity of 72.65%, specificity of 100.0%, and AUC of 86.32%. For the subtype diagnosis, the best AUC was 99.46% for medullary thyroid cancer with an average of 237.6 s per slide.

CONCLUSIONS

Within our testing dataset, the proposed method accurately diagnosed the thyroid nodules during surgery.

The Role of Frozen Section Examination in Thyroid Surgery

In endocrine pathology, frozen section (FS) examination is most commonly used for the intraoperative evaluation of thyroid and parathyroid tumors, as well as cervical lymph nodes. In the past, frozen section was considered a fundamental tool in thyroid surgery. However, with advancements in preoperative ultrasound and fine-needle aspiration biopsy (FNAB), there have been increasing queries about its routine use due to the improved preoperative diagnosis. Nowadays, while the use of FS during thyroidectomy has decreased, it is still used as an additional method for different purposes intraoperatively. FS may not always provide definitive results. If FS will alter the surgical plan or extent, it should be applied. Routine FS is not recommended for evaluating thyroid nodules. But in addition to FNAB, if FS results may change the operation plan or extent, they can be utilized. FS should not be applied for thyroid lesions smaller than 1 cm, and the entire lesion should not be frozen for FS. For the assessment of thyroid nodules, the use of FS is recommended based on the Bethesda categories of FNAB. In Bethesda I category nodules, FS may contribute to distinguishing between malignant and benign lesions and guide surgical treatment. In Bethesda II nodules, where the malignancy rate is low, the performance of FNAB and FS can be compared, but it's not recommended due to the lack of a significant contribution to the surgical strategy. The sensitivity of FS in Bethesda III and IV nodules is low; its contribution to the diagnosis is limited, and it does not provide an apparent benefit to treatment; therefore, it is not recommended. In Bethesda V nodules, FS can effectively confirm the malignancy diagnosis, contribute to the surgical strategy, and reduce the possibility of completion thyroidectomy, and accordingly, it is recommended for use. Nonetheless, in Bethesda V nodules with a benign FS report, the malignancy rate remains high, so it should not be used to rule out malignancy. In Bethesda VI nodules, the performance of FS is lower or comparable to FNAB and does not significantly contribute to the treatment strategy; hence, it is not recommended. Particularly in patients with papillary thyroid cancer, intraoperative FS can be effective in detecting extrathyroidal extension and can assist the surgeon in determining the extent of thyroid surgery and central neck dissection. FS has high sensitivity and specificity in evaluating the lymphatic status of the central region intraoperatively and can be used to determine the extent of central compartment node dissection. During thyroidectomy, FS examination can be used in recognizing parathyroid tissue and distinguishing it from fatty tissue, thymus, thyroid, lymph nodes, especially in differentiating metastatic lymph nodes.

Thyroid nodules: Global, economic, and personal burdens

Thyroid nodules have garnered attention due to changes in population surveillance systems and rising concerns about the associated financial burden on healthcare systems, payers, and patients. In this review, we find that prevalence rates vary widely based on method of detection and may particularly pronounced in asymptomatic patients undergoing routine screening. Incidence rates may be particularly rising in lower-income and middle-income countries and may be declining in higher-income countries. Despite high incidence rates, survival rates continue to be as high as 97% for papillary thyroid cancer. Over the last few decades, thyroid nodule workup and management has grown more sophisticated with the advent of fine-needle aspiration biopsy, specialized biomarkers, and molecular testing. However, gaps remain in risk stratification that can lead to substantial costs of care. Certain molecular tests, such as the Afirma Gene Sequencing Classifier can lead to a cost per diagnosis of $17,873 while achieving only mild decreases in diagnostic lobectomies for patients (11.6% to 9.7% in one study). Out-of-pocket costs associated with thyroid nodule management continue to drive significant financial toxicity for patients, especially for individuals with thyroid cancer. Financial toxicity has been defined as a term that describes how direct and indirect medical costs of cancer care strain patients and households via decreased income, assets, and spending on basic necessities. Recent studies suggest that such toxicity can lead to adverse financial outcomes, such as foreclosure and bankruptcy. Additional cost-effectiveness analyses are needed to improve existing thyroid nodule management systems and new clinical tools are needed to avoid unnecessary workup and management.

Frozen section in thyroid gland follicular neoplasms: It's high time to abandon it!

Thyroid nodules are a very common clinical condition. The 2015 American Thyroid Association (ATA) guidelines recommend surgical excision for Bethesda IV nodules. The use of intraoperative frozen section (FS) has been recommended as a strategy to tailor the extent of the initial surgery. We critically evaluated the literature that discusses the utility and cost-effectiveness of FS to make an intraoperative decision in patients with thyroid nodules classified as follicular neoplasm. FS should not be recommended as a routine intraoperative test to assess for malignancy in thyroid follicular patterned lesions due to its low performance; the high number of deferred results; the inability to adequately assess histologically defining features; the improvements in risk stratification guiding total thyroidectomy; and the low cost-effectiveness of FS.

Medicolegal lessons learned from thyroidectomy-related lawsuits: an analysis of judicial precedents in South Korea from 1998 to 2019

Background

Thyroid cancer is one of the most common cancers in South Korea, and thyroidectomy is still frequently performed. As new diagnostic methods have led to a significant increase in the early detection of thyroid cancer worldwide, medical disputes related to thyroid surgery are also likely to increase. The purpose of this study was to investigate the causes of medical disputes related to thyroidectomy and to identify ways to prevent unnecessary disputes and malpractice.

Methods

We analyzed 35 judicial decisions involving thyroidectomy in South Korea from January 1998 to July 2019.

Results

The most common cause of lawsuits was "performance error during surgery" (n=19), especially "recurrent laryngeal nerve (RLN) injury" (n=7), of which five cases were ruled medical malpractice. For lawsuits involving misdiagnosis (n=14), five regarding fine needle aspiration cytology (FNAC) and frozen section examination were ruled malpractice. The most common malpractice related to informed consent was "lack of explanation about surgery complications" (n=10).

Conclusions

Surgeons should follow guidelines to protect themselves from diagnostic error dispute; performing FNAC more often might also prevent lawsuits. When the courts judge the surgeon's negligence in cases of RLN injuries, whether bilateral or unilateral, it is necessary to consider fully the surgeon's efforts to prevent RLN injuries. Providing information and building trust through sufficient patient-doctor communication is crucial.