Thyroid nodules in the gulf: Renewed interest and ongoing debate

In the current issue of the Journal, Alawadhi et al. shared their review of the accuracy of fine-needle aspiration (FNA) cytology for detecting cancer in resected thyroid nodules at a referral center, namely, The Cleveland Clinic Abu Dhabi.[[1]] The article renewed the increased interest over the past few years in the epidemiology and clinical management of thyroid cancer in the Arabian Gulf and more specifically in the United Arab Emirates (UAE).

The advent of thyroid US in general and its wider availability in the recently developed countries of the region have increased the incidental discovery of thyroid nodules and hence the incidence of thyroid cancer in the region. The accumulated prevalence of thyroid cancer among thyroid nodules has varied from 5% to 14% with peculiar peak incidence occurring before the age of 45 years was observed by several groups.[[2]],[[3]],[[4]] The average age in this study was 41, and the median age was 40 years making it a decade earlier than what is seen in the USA and Western countries in general. However, the most commonly encountered type of thyroid cancer remains papillary, followed by follicular thyroid cancer with a female-to-male ratio, swirling around a ratio of 4.9:1.

Considering that 82.1% of the subjects in this study were UAE nationals, it would have been valuable if the authors referred to recently published local or regional studies comprising subjects of similar or closer population background. Unfortunately, they chose to make comparisons with data from an Egyptian study that included subjects of minimal similarity to their study population. A meta-analysis of all published data from the Gulf and neighboring regions is called for to explore differences and similarities and may shed more lights on any peculiarities of the region.

FNA of the thyroid has been adopted worldwide as an efficient and reliable means for the evaluation of thyroid nodules with a diagnostic sensitivity of 89%–98% and a specificity of 92% and false-negative results not exceeding 10%.[[4]] In fact, locally reported false-negative rates of FNA did not exceed 6% even after 1-year follow-up.[[5]] This contrasts remarkably with the results described in the current paper.[[1]] Reporting a sensitivity as low as 52%, a negative predictive value of 64%, a high false rate of 48%, and an accuracy of around 72% need more explanation. Such rates would be explained by either poor sampling or interpretation or to thyroid nodule size exceeding 4 cm where the false-negative rate would have been expected to be high.[[6]] Unfortunately, no tumor size data were reported, and negative and positive predictive values were calculated with no preliminary knowledge of thyroid cancer prevalence in the UAE.

Bethesda classification adopted in this study is accepted worldwide as being a reliable method to classify and stratify thyroid nodules.[[7]] Of note, several publications from the gulf region have lately focused on the group of indeterminate thyroid nodules (Atypia of unknown significance [AUS] and follicular neoplasm of unknown significance) with rates of cancer varying between 20% and 45%.[[8]] This contrasts with the higher figures observed in this study (38.1% and 69.1% for AUS and follicular neoplasm, respectively). This could be partly due to referral bias, lack of histology review to discern the group of NIFTP, expertise variability in cytology, and/or statistical bias. For instance, organizing cytology results as either benign or malignant but lumping in this group benign, AUS, follicular neoplasm subgroups is inappropriate. Also, classify histology results as either nonneoplastic or neoplastic (suspicious for malignancy and malignant) is confusing and inappropriate. In fact, when we did reclassify the cytology results as either benign (Bethesda 2) or malignant (Bethesda 4 and 5) while excluding the indeterminate group, the statistical figures changed to FNA sensitivity of 80% (vs. 50.1%); reducing the high false-negative rate to 20% instead of 48.9% while maintaining a specificity of 90%.

Finally, the high rate of thyroid cancer stated in this study could be attributed to either a preselection of high-risk thyroid tumors been referred to a tertiary hospital or to incidentally discovered micropapillary thyroid cancers unrelated to the biopsied tumors.

Overall, it is an interesting study reflecting on a local experience with unexpectedly debatable results. Further systematic reviews and narrations of all the published data from the region are called for to present a balanced overview of the condition and its management.

Authors' contribution

Equal.

Compliance with ethical principles

No ethical approval is required.

Conflict of Interest

Nil.

• References

• 1 Alawadhi R, Matalkah A, Ahmed N, Alduaij A, Sabri A, El-Kaissi S, et al. Review of accuracy of fine-needle aspiration cytology for detecting cancer in resected thyroid nodules at a referral hospital. J Diabetes Endocr Pract 2021;4:21-4.
• 2 Al-Zaher N, Al-Salam S, El Teraifi H. Thyroid carcinoma in the United Arab Emirates: Perspectives and experience of a tertiary care hospital. Hematol Oncol Stem Cell Ther 2008;1:14-21.
• 3 Alseddeeqi E, Baharoon R, Mohamed R, Ghaith J, Al-Helali A, Ahmed LA. Thyroid malignancy among patients with thyroid nodules in the United Arab Emirates: A five-year retrospective tertiary Centre analysis. Thyroid Res 2018;11:17.
• 4 Azhar M, Aziz F, Almuhairi S, Alfelasi M, Elhouni A, Syed R, et al. Decline in radioiodine use but not total thyroidectomy in thyroid cancer patients treated in the United Arab Emirates - A retrospective study. Ann Med Surg (Lond) 2021;64:102203.
• 5 Khalil AB, Dina R, Meeran K, Bakir AM, Naqvi S, Al Tikritti A, et al. Indeterminate thyroid nodules: A pragmatic approach. Eur Thyroid J 2018;7:39-43.
• 6 Pinchot SN, Al-Wagih H, Schaefer S, Sippel R, Chen H. Accuracy of fine-needle aspiration biopsy for predicting neoplasm or carcinoma in thyroid nodules 4 cm or larger. Arch Surg 2009;144:649-55.
• 7 Cibas ES, Ali SZ. The 2017 Bethesda system for reporting thyroid cytopathology. Thyroid 2017;27:1341-6.
• 8 Al-Abbadi MA, Shareef SQ, Yousef MM, Almasri NM, Mustafa HE, Aljawad H, et al. A follow-up study on thyroid aspirates reported as atypia of undetermined significance/follicular lesion of undetermined significance and follicular neoplasm/suspicious for follicular neoplasm: A multicenter study from the Arabian Gulf region. Diagn Cytopathol 2017;45:983-8.

Publication History

Received: 25 March 2021

Accepted: 25 March 2021

Article published online:
06 July 2022