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Table of Contents
ORIGINAL ARTICLE
Year : 2021  |  Volume : 4  |  Issue : 1  |  Page : 19-22

Accuracy of fine-needle aspiration cytology for detecting cancer in resected thyroid nodules at a referral hospital


1 Department of General Surgery, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates
2 Department of General Surgery, Cleveland Clinic Abu Dhabi, Digestive Disease Institute, Abu Dhabi, United Arab Emirates
3 Department of Anatomic Pathology, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates
4 Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Lebanese American University, Byblos, Lebanon
5 Department of Endocrinology, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates

Date of Submission01-May-2020
Date of Decision24-May-2020
Date of Acceptance17-Oct-2020
Date of Web Publication13-Apr-2021

Correspondence Address:
Dr. Yasir Akmal
Cleveland Clinic Abu Dhabi, Digestive Disease Institute, Abu Dhabi
United Arab Emirates
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdep.jdep_5_20

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  Abstract 

Background: Thyroid nodules are a common presentation in clinical practice. Fine-needle aspiration cytology (FNAC) is a useful method of triaging patients between benign, suspicious, and malignant categories. Materials and Methods: This is a retrospective review of the electronic medical record of all surgical thyroid patients presenting to our institution between July 2015 and June 2017. The cytological and histological data were reviewed and correlated based on the Bethesda system for reporting thyroid cytopathology. Results: Two hundred and seven patients underwent thyroidectomies during that period of which 164 had preoperative FNAC. The female-male ratio of 4.9:1. On histology, 52% of nodules were benign and 48% of nodules were malignant. When comparing with cytologic diagnosis, FNAC showed a sensitivity of 52%, specificity of 95%, positive predictive value of 92%, negative predictive value of 64%, false positive rate 5%, and false negative rate 48%. Total accuracy was found to be 72%. Conclusion: FNAC is a useful tool in deciding management options for patients, but has limitations, particularly when evaluating follicular lesions. This leads to discrepancy in the calculation of statistical values in literature.

Keywords: Fine needle-aspiration, middle east, thyroid cancer, thyroid nodules, thyroidectomy


How to cite this article:
Alawadhi R, Matalkah A, Ahmed N, Alduaij A, Sabri A, El-Kaissi S, Akmal Y. Accuracy of fine-needle aspiration cytology for detecting cancer in resected thyroid nodules at a referral hospital. J Diabetes Endocr Pract 2021;4:19-22

How to cite this URL:
Alawadhi R, Matalkah A, Ahmed N, Alduaij A, Sabri A, El-Kaissi S, Akmal Y. Accuracy of fine-needle aspiration cytology for detecting cancer in resected thyroid nodules at a referral hospital. J Diabetes Endocr Pract [serial online] 2021 [cited 2022 Oct 7];4:19-22. Available from: https://www.jdeponline.com/text.asp?2021/4/1/19/313677


  Introduction Top
Thyroid nodules are a common condition in clinical practice, with their prevalence being as high as 60%.[1] However, the majority of thyroid nodules are benign, with only 4.5%–6% found to be malignant.[2],[3] In the United Arab Emirates (UAE), thyroid carcinoma is the most common endocrine malignancy, and the third most common cancer in females overall, and its incidence is progressively increasing.[4],[5] With the worldwide increase in cancer burden which is reciprocated in the UAE, evaluation of thyroid nodules is of utmost importance for determining management options.

Surgical management of suspicious thyroid nodules is the mainstay of treatment. The importance of preoperative evaluation of thyroid nodules by determining whether they are benign or malignant, is to avoid unnecessary surgical intervention and its complications.[6],[7] The complications of surgical intervention include, but are not limited to nerve injury, damage to parathyroid glands causing hypoparathyroidism, and life-long hypothyroidism requiring medication. Aside from the technical complications of management, social and psychological distress is a major factor of patient experience. Therefore, the decision to undergo surgery for patients and physicians alike is greatly influenced by the cytological results of fine-needle aspiration (FNA).

FNA is a safe, reliable, and cost-effective procedure for guiding patient management options.[8] This is especially true if ultrasound-guided techniques are used, which allows for better identification of nodules and more accurate sample collection.[9] Although the usefulness of FNA as a diagnostic tool is validated, there are some limitations to its use such as risk of false-negative and false-positive values, inadequate sample collection, and inability to definitively determine whether some samples are benign or malignant.[10],[11]

The objectives of this study are to identify the correlation of cytological results to final pathology results of FNA biopsy in patients treated at Cleveland Clinic Abu Dhabi in comparison to regional and global rates. This will therefore determine the relevance of FNA as a diagnostic tool in the UAE population. This study will also look at the epidemiological difference between overall patient populations.
  Materials and Methods Top
The records of all patients who underwent thyroidectomies at Cleveland Clinic Abu Dhabi, UAE between July 2015 and June 2017 were retrospectively reviewed. The Electronic Medical Records (EPIC database) were used to retrieve information such as patients' age, sex, ethnicity, ultrasound findings, fine-needle aspirate cytology (FNAC) results, and final histological results. All of the surgical pathology was performed and reviewed at Cleveland Clinic Abu Dhabi. However, some cytological FNA studies were performed at outside facilities in addition to Cleveland Clinic Abu Dhabi.

Following sample collection, the interpreting clinical pathologist used the Bethesda system for reporting thyroid cytopathology to divide the samples into six diagnostic categories: (1) nondiagnostic, (2) benign, (3) atypia of undetermined significance, (AUS) or follicular lesion of undetermined significance, (4) follicular neoplasm or suspicious for a follicular neoplasm, (5) suspicious for malignancy, and (6) malignant.

Postoperatively, the results of FNAC were compared with histological diagnosis. For the purpose of this study, the definitive histological diagnoses was grouped into “No Cancer” and “Cancer” to assess for concordance and discordance between the cytological and histological results.

Calculations were then made to determine the following parameters: sensitivity, specificity, diagnostic accuracy, positive predictive value, and negative predictive value using Microsoft Excel software.
  Results Top
A total of 207 patients underwent thyroidectomy during the study period. Of these patients, 164 had an FNA preoperatively and these were the patients included in this study for final analysis. Of the total study population, 172 patients were female and 35 patients were male, with a female-to-male ratio of 4.9:1. The patients included in this study ranged in age between 14 and 81 years with an average age of 41, and median age of 40 [Table 1]. Considering the diverse communities that compromise the UAE population, 37 (17.9%) patients included in study were expatriates and 170 (82.1%) patients were UAE nationals.
Table 1: Epidemiological information of patients

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Of patients included in this study, 48% were found to have malignant lesions on pathology and 52% had benign lesions [Table 2]. Out of 207 patients, 164 underwent FNAC preoperatively with 50 cases reported as benign (30.5%), 42 cases of AUS (25.6%), 23 cases of follicular neoplasm (14.0%), 13 cases of suspicious for malignancy (7.93%), 35 cases of malignant samples (21.3%), and 1 case of nondiagnostic (0.61%) [Table 3].
Table 2: Pathological diagnosis

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Table 3:Cytological diagnosis case distribution based on Bethesda classification

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When comparing the cytology results to the histopathology results from the 50 benign cases, 34 (68%) were diagnosed as benign nodules (colloid nodules, or multinodular goiter/nodular hyperplasia), 2 (4%) as lymphocytic (Hashimoto) thyroiditis, 3 (6%) as follicular adenoma, and 11 (22%) cases as carcinoma. From the 42 cases classified as AUS 17 (40.5%) were diagnosed as benign nodules, 1 (2.38%) as Hashimoto thyroiditis, 1 (2.38%) as Graves disease, 7 (16.7%) as follicular adenoma, and 16 (38.1%) as carcinoma. From the 23 cases classified by cytology as follicular neoplasm 7 (30.4%) were diagnosed as benign nodules, 2 (8.70%) were diagnosed as follicular adenoma, and 14 (60.9%) were diagnosed as carcinoma. Out of the 13 cases that were shown to be suspicious for malignancy, 10 (76.9%) were diagnosed as carcinoma and 3 (23.1%) were diagnosed as multinodular goiter. Out of the 35 cases shown to be malignant on cytology, 34 (97.1%) were diagnosed as carcinoma and 1 (2.86%) as multinodular goitre [Table 4].
Table 4: Cytological diagnosis and corresponding final pathological diagnosis

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Of the 164 patients, 115 cases were cytological diagnosed as benign (benign, AUS, follicular neoplasm). Histologically, 41 (36%) were found to be neoplastic and 74 were nonneoplastic [Table 5]. Forty-eight cases were considered neoplastic on cytology (suspicious for malignancy, and malignant). Forty-four (92%) cases were diagnosed as malignant histologically while 4 were diagnosed as nonneoplastic. Therefore, FNA showed a sensitivity of 52%, specificity of 95%, positive predictive value of 92%, negative predictive value of 64%, false-positive rate 5%, and false-negative rate 48%. Total accuracy was found to be 72%.
Table 5: Cytological diagnosis relationship to pathological diagnosis and cancer risk

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  Discussion Top
Surgical intervention is the mainstay of management of suspicious thyroid nodules. Preoperative assessment of thyroid nodules is paramount to reduce the unnecessary complication rates of thyroidectomies. Preoperative evaluation may include imaging by ultrasound, computed tomograpy or magnetic resonance imaging, laboratory investigation, as well as cytological investigation by FNAC. FNAC is regarded as the most reliable preoperative assessment to determine if surgical intervention is needed. FNAC is however not free from limitations, most significantly being its inability to confidently determine if nodules are malignant, as well as limitations with sample collection.[8],[9],[10],[11]

It is known that thyroid nodules are predominantly present in middle-aged female patients.[12],[13],[14],[15] This has been further demonstrated in our study, which has found a female predominance where 83% of patient population were female and a female-to-male ratio of 4.9:1. The median age of patients in this study was 40, with almost half the patient population in the 21–40 years age group. Age distribution is slightly younger in neoplastic (mean 39), than nonneoplastic (mean 42). These epidemiological trends are shared with several regional and global studies, most notably a study carried out by Egyptian National Cancer Institute by Sinna and Ezzat showed a female-to-male ratio of 5.2:1 and median age of 44.[11]

In this study, the cohort of patients included all surgical patients who underwent thyroidectomies. Surgeries performed included hemi-thyroidectomies, total thyroidectomies, and completion thyroidectomies depending on the indication. The indications for thyroidectomies range from benign to malignant conditions including but not limited to: obstructive symptoms due to goiter, hyperthyroidism not medically managed, cosmetically unappealing thyroid nodules, and thyroid carcinoma.

Inclusion of only surgical patients provides us with the advantage of having the final histology of all patients, allowing us to correlate it with the cytological findings of FNA. Fifty-two percent of our patients were found to have benign lesions on histology, while 48% were found to be malignant. The predominance of benign lesions on cytology is synonymous with what is found in literature[3],[4] However, our study shows a higher rate of benign lesions, as compared to literature. In the benign lesions, the majority (78%) were hyperplastic nodules, while papillary carcinoma (88%) was the most common in malignant lesions, which is similar to what is seen in literature.[8][16],[17],[18]

The sensitivity and specificity in our study are 52% and 95%, respectively. The high specificity is shared with what is found in literature indicating that FNAC is a useful in ruling in the diagnosis of malignancy when atypical features are found. The sensitivity of FNAC varies in literature between 55% and 95% and our value is on the lower end of the spectrum.[8],[10],[11],[19],[20] The variation exists due to the different methods of calculation of these variables in different studies. The discrepancy arises mostly in the categorizing of Bethesda 3 (AUS) and Bethesda 4 (follicular neoplasm) into benign or malignant categories. Some studies consider a true-positive result of malignancy to include only Bethesda 5 and Bethesda 6, such as in our study and Tseng et al.[10] While, in other studies, Bethesda 4 is considered in malignant category; such as in Sinna and Ezzat[11] Chieng et al.[19] Due to the variation of sensitivity of FNAC in literature, it is use in reassurance and ruling out malignancy should be done with caution. The clinical presentation and clinician's suspicion based on history, physical examination, and laboratory and imaging findings should partially compensate for the low sensitivity of FNAC.

Our study showed a total accuracy of 72.4%, which is within the range of what is found in literature (67%–97%).[8],[10],[11],[19],[20] Drawbacks of FNAC include its inability to confidently ascertain if a sample is benign or malignant. This is especially true with respect to follicular lesions because the differentiation between follicular adenoma and follicular carcinoma requires identification of vascular or capsular invasion which can only be determined by histology. Due to this fact, there is a high cancer risk (60.9%) in Bethesda 4 (Follicular neoplasm) found in this study, which is similar to what is found in literature.
  Conclusion Top


FNAC is a useful tool in management of patients with thyroid nodules. However, it is not without limitations, which lead to its reduced accuracy, especially with respect to follicular lesions. The use of FNAC should be correlated with overall clinical picture in addition to findings from other modalities to maximize its accuracy. Furthermore, the current study demonstrates that the sensitivity, specificity, and accuracy of FNAC in a UAE population are similar to rates in other studies from other regions of the world.

Authors' contribution

All authors contributed to cenception and conduct of the styd and to the drafting and revision of the manuscript. They all have reviewed and approved the final version of the manuscript.

Financial support and sponsorship8

Nil.

Conflicts of interest

There are no conflicts of interest.

Compliance with ethical principles

The study was conducted as quality improvement exercise of our experience. It was approved by the institutional review board of Cleveland Clinic Abu Dhabi {IRB REC number is: B-2017-001).

 
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Davies L, Welch HG. Current thyroid cancer trends in the United States. JAMA Otolaryngol Head Neck Surg 2014;140:317-22.  Back to cited text no. 14
    
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