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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 22  |  Issue : 2  |  Page : 69-72

Accuracy of fine-needle aspiration in diagnosing of well-differentiated thyroid cancer at a tertiary care center


1 Department of Otolaryngology-Head and Neck Surgery, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
2 College of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia

Date of Submission14-Apr-2020
Date of Decision10-May-2020
Date of Acceptance26-May-2020
Date of Web Publication30-Dec-2020

Correspondence Address:
Dr. Mazin A Merdad
Department of Otolaryngology-Head and Neck Surgery, King Abdulaziz University, Jeddah
Kingdom of Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/SJOH.SJOH_12_20

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  Abstract 


Background: Thyroid cancer is the third-most common cancer in Saudi females and males. The Bethesda System for Reporting Thyroid Cytopathology provides a diagnostic framework that can be used in surgical decision-making that allows the use of standardized treatment algorithms for each category. The present study aims to assess the accuracy of fine-needle aspiration (FNA) in diagnosing well-differentiated thyroid cancer in comparison to the corresponding final histopathological results. Methodology: This was a retrospective review of 404 patients who underwent FNA cytology, followed by thyroid surgery during 2010–2018. Data were collected from the medical records of these patients. Results: Based on the final histopathological examination results, 63% of the tested nodules were benign and 36% were malignant. The tested thyroid nodules with Bethesda categories II, III, IV, V, and VI were diagnosed as malignant in 8.7% 33.3%, 50%, 60%, and 94.4%, respectively. FNA (Bethesda categories II and VI) for benign and malignant lesions revealed a sensitivity, specificity, positive predictive value (PPV), and negative predictive value of 79.69%, 97.84%, 94.44%, and 91.28%, respectively. Conclusion: FNA is a reliable diagnostic tool for diagnosing thyroid nodules with a high specificity and PPV. The capability of the relatively high overall malignancy rate can be explained by the nature of our institution, being a major regional tertiary and cancer center. The size of the nodule and its location, body mass index, and age had no significant effect on the accuracy of the FNA.

Keywords: Bethesda System for Reporting Thyroid Cytopathology, fine-needle aspiration, malignancy risk, thyroid cancer


How to cite this article:
Merdad MA, Alghafli ZI, AlSharif SM, AlQathmi MS, Sindi GM, Marzouki HZ. Accuracy of fine-needle aspiration in diagnosing of well-differentiated thyroid cancer at a tertiary care center. Saudi J Otorhinolaryngol Head Neck Surg 2020;22:69-72

How to cite this URL:
Merdad MA, Alghafli ZI, AlSharif SM, AlQathmi MS, Sindi GM, Marzouki HZ. Accuracy of fine-needle aspiration in diagnosing of well-differentiated thyroid cancer at a tertiary care center. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2020 [cited 2021 Apr 23];22:69-72. Available from: https://www.sjohns.org/text.asp?2020/22/2/69/305458




  Introduction Top


Approximately 53,990 patients are diagnosed with thyroid cancer annually in the United States.[1] Similarly, thyroid cancer in Saudi Arabia accounts for 8.2% of all cancers. Moreover, it is the third-most common cancer in both female and male individuals and is the second-most common cancer in women.[2],[3],[4],[5] During the last two decades, fine-needle aspiration (FNA) has emerged as the most simple and reliable tool for diagnosing thyroid nodules, with an estimated overall sensitivity and specificity of >90%.[6],[7] This study aims to assess the accuracy of FNA in diagnosing well-differentiated thyroid cancer by comparing it to the corresponding final histopathologic results. Moreover, the factors affecting the accuracy of FNA are assessed.


  Methodology Top


Data were retrospectively collected from 404 patients who underwent thyroid surgery for well-differentiated thyroid cancer at King Abdulaziz University Hospital between 2010 and 2018. Our institutional review board approved the study. Data collected from the electronic medical records included demographic information of the patients (age, gender, and body mass index [BMI]), medical history, histopathological examination results (pathological diagnosis, size, and location of the lesion, volume of the nodule, and maximum diameter of the nodule), and sonographic test findings. Ultrasound-guided FNA (US-guided FNA) was performed for thyroid nodules of ≥ 1.0 cm in maximal dimension on ultrasonography. Both the site and size of the nodule assessed through biopsy were correlated to the final histopathological results to ensure that the same nodule was analyzed on both cytological and histological examinations. FNA results were classified according to the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC).[8] The final histopathological diagnosis was classified as benign or malignant. Statistical analysis was conducted using the Statistical Package for the Social Sciences software (SPSS),version 22, Chicago, IL, USA.

Inclusion and exclusion criteria

The study included well-differentiated thyroid cancer (papillary and follicular) between the years 2010 and 2018 and patients older than 15 years were included in the study. Patients with incomplete data or final pathology other than well-differentiated thyroid cancer (papillary and follicular) were excluded from the study.


  Results Top


A total of 404 patients with complete data were included in the analysis. The mean age of our patients was 43.1 years, and 85% were women. The mean maximum diameter of the dominant nodule was 22.6 mm. The final histopathological examination revealed that 63% of the tested nodules were benign and 36% were malignant. The demographic characteristics of the participants and thyroid nodule variables are shown in [Table 1]. The Bethesda categorization of the FNA samples is depicted in [Figure 1]. Of the 51.2% benign lesions on FNA (Bethesda II), approximately 4.5% of the lesions were malignant based on the final histopathological examination, whereas the tested thyroid nodules with Bethesda categories III, IV, V, and VI were diagnosed as malignant in 33.3%, 50%, 60%, and 94.4%, respectively [Table 2]. Sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) of FNA (Bethesda categories II and VI) of the malignant and benign lesions are displayed in [Table 3]. International comparison of the Bethesda system is summarized in [Table 4].
Table 1: Demographic characteristics of the participants (n=404)

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Table 2: Frequency and malignancy rates using The Bethesda System for Reporting Thyroid Cytopathology category

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Table 3: Sensitivity analysis of benign and malignant fine-needle aspiration: (Bethesda categories II and VI)

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Table 4: Comparison of percentage of cases in each Bethesda category and risk of malignancy on histopathology specimens between the present study and other studies from other countries

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Figure 1: Fine-needle aspiration categorization (Bethesda system)

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  Discussion Top


Thyroid cancer is the second-most common cancer among women in Saudi Arabia.[2],[9] This study aimed to assess the accuracy of FNA in diagnosing well-differentiated thyroid cancer and in detecting factors affecting the accuracy of FNA.

In our study, the overall risk of malignancy (ROM) according to the Bethesda categories of benign lesions, atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS), and follicular neoplasms were 8.7%, 33.3%, and 50%, respectively. This is in contrast with the general ROM according to the guidelines showing the following rates of malignancy: 0%–3% for benign lesions, 5%–15% for AUS/FLUS, and 15%–30% for follicular neoplasms.[8] Despite the fact that there is a new second edition of The Bethesda system for reporting thyroid cytopathology (TBSRTC) published, where the ROM and clinical management of noninvasive follicular thyroid neoplasm with papillary like nuclear features (NIFTP) was demonstrated.[10] Yet, NIFTP cytological features were not used in this study, so we compared our results with first edition of TBSRTC. Other institutions have previously reported higher ROM using the TBSRTC.[11],[12],[13],[14],[15] In addition, a recent meta-analysis of three registries (CESQIP, Eurocrine, and UKRETS) reported higher ROM for the lower Bethesda diagnostic categories (I, II, and III) in 19.2%, 12.7%, and 31.9%, respectively.[16] We compared our results with multiple international studies and are summarized in [Table 4].[17],[18],[19],[20] The higher rates of malignancy were noted in Bethesda category II (benign), which could be explained by the local referral system and the fact that some of the FNA reports were conducted in other institutions. Furthermore, our institution up to last year did not have a dedicated head and neck pathologists and cytopathologists, and this could have affected the accuracy of reporting. The ROM in our study for suspicious and malignant lesions based on FNA was comparable to those of most publications, including the National Cancer Institute guidelines.

Several factors affect the accuracy of FNA in diagnosing thyroid nodules, including size and location of the lesions, BMI, and age.[5],[21],[22],[23] Pinchot et al. found that the size of the nodule (>4 cm) is correlated to a false-negative rate of 8%.[21] However, in our study, the size and location of the lesion, BMI, and age had no statistically significant effect on the accuracy of the FNA.

The analysis of FNA in our cohort revealed a sensitivity of 79.7%, specificity of 97.8%, PPV of 94.4%, and NPV of 91.3%. Our overall results are in accordance with those of other published results, where the FNA cytology sensitivity was between 70% and 92% and the specificity was between 74% and 99%.[24],[25],[26],[27],[28] This revalidates that FNA cytology is more specific than sensitive in detecting thyroid malignancy. FNA is the only one component of thyroid nodule assessment. Ancillary information for risk stratification (patient age, nodule size, sonographic features, and the presence of lymphadenopathy) decides the optimal treatment approach.

The limitation of this study includes its retrospective nature, wherein the enrolled patients were managed by variant teams and assessed by different cytopathologists. In addition, there were some inconsistencies in our medical records. The current study evaluated patients from a single tertiary institution, and the findings might not be reflective of the overall general practices and population.

Newer molecular tests, such as Afirma and ThyroSeq, have the ability to better categorize the cytologically indeterminate nodules' Bethesda categories (III and IV) according to their ROM. Such ancillary instruments can be used for further association with clinicopathological characteristics and the improvement of risk stratification in indeterminate nodules. Incorporating genetic tests in the thyroid nodule investigation algorithm may help some patients avoid unnecessary surgery.


  Conclusion Top


FNA remains a reliable method for categorizing thyroid nodules with excellent specificity. Our study reported a generally higher rate of malignant nodules. Size of the nodule and its location, BMI, and age had no significant effect on the accuracy of the FNA.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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