Quantifying the differences in surgical management of patients with definitive and indeterminate thyroid nodule cytology

doi:10.1016/j.ejso.2019.10.004

European Journal of Surgical Oncology

Volume 46, Issue 2, February 2020, Pages 252-257

https://doi.org/10.1016/j.ejso.2019.10.004 Get rights and content

Abstract

Introduction

Thyroid nodules are increasingly common. Despite being an essential pre-operative diagnostic tool, up to 30% of fine needle aspirate cytology (FNAC) yields a non-definitive diagnosis. This study aimed to quantify differences in surgical management of patients with definitive and indeterminate thyroid nodule cytology, and determine if clinical factors can improve cytological diagnosis.

Materials and methods

Patients who underwent thyroidectomy for nodules from 2001 to 2015 were recruited. Those with benign and malignant preoperative cytology were included in the “definitive diagnosis” (DC) group; patients with all other preoperative cytology results were included in the “indeterminate diagnosis” (IC) group. We compared demographics and procedures between these groups. Clinical factors and demographics were also compared between patients with benign and malignant histology in the IC group.

Results

A total of 3821 cases were included. A significantly larger proportion of the IC patients had a hemithyroidectomy (IC 69% vs. DC 39%, p < 0.001) initially, and also had a significantly higher rate of two-stage surgery compared to the DC group (IC 17% vs. DC 11%, p < 0.001). Patients in the DC group were twice as likely to undergo concurrent central lymph node dissection for papillary and medullary cancers than the IC group (p < 0.001). Overall, up to 60% of IC patients had been over- or under-treated at initial surgery. The clinical factors examined were not significantly associated with higher risk of malignancy in IC patients.

Conclusion

This study highlights the potential for improved preoperative diagnosis to streamline decision making for surgical management of patients with thyroid nodules.

Introduction

The prevalence of thyroid nodules in the adult population is reportedly up to 50% [1]. This figure is increasing due to the discovery of incidental thyroid nodules on diagnostic imaging for other indications. Although only approximately 5% of clinically significant thyroid nodules are malignant, the incidence of thyroid cancer is also increasing [2,3]. In 2017, thyroid cancer was estimated to be the third most commonly diagnosed cancer among Australian women aged 25–49 years [3].

Fine needle aspiration cytology (FNAC) is a key component of thyroid nodule assessment and malignancy risk stratification, along with clinical assessment and ultrasonography (US). Clinical decision making is relatively straightforward if the FNAC confirms a benign or malignant result. However, in 15–30% of cases the FNAC returns an indeterminate result that carries a risk of malignancy ranging from 5 to 75% [4]. This creates a clinical dilemma for the clinician and patient. Even after repeat cytology, over 20% of these nodules remain indeterminate [5].

The lack of diagnostic certainty affects the clinician's ability to confidently recommend a) surgery, and b) the extent of surgery if deemed necessary – both in terms of the extent of thyroidectomy and the need for central lymph node dissection. While diagnostic hemithyroidectomy is a procedure associated with a low complication rate, it can be a procedure of compromise when it is not the definitive surgery required for a given pathology. However, it is also important to recognise that the decision for surgery or extent of surgery does not solely rest on the malignancy status of the nodule, but also the overall symptomatology and other factors.

In recent years, adjuncts to cytology such as mutation testing have been developed and continue to be refined. While some investigators have reported promising results, their clinical utility is not uniformly demonstrated, and they are not readily available outside the United States [6]. Therefore, this study aimed to 1) quantify the potential room for improvement in clinical decision making with improved pre-operative diagnosis of thyroid nodules, taking into account other non-malignancy related indications for surgery; and 2) investigate if clinical factors can further improve the pre-operative diagnostic accuracy of thyroid nodules without definitive cytology.

Section snippets

Materials and Methods

This is a case-control study from the Monash University Endocrine Surgery Unit (MUESU). Prospectively collected clinical data on patients undergoing thyroidectomy over a 15-year period from 2001 to 2015 was used for the analysis. The 2015 cut-off was chosen to minimise the effect of updated recommendations on the treatment of low risk papillary thyroid cancers [7]. The study group comprised of all patients who had fine needle aspiration cytology (FNAC) of a thyroid nodule with corresponding

Results

A total of 3821 cases with complete data were included in the analysis. Of these, 2582 (68%) cases were included in the DC group, and 1239 (32%) cases were in the IC group. Another 1732 cases were excluded due to incomplete data (N = 1474), previous thyroid surgery (N = 210) or lymph node dissection only (N = 48).

Discussion

The clinical impact of the lack of a definitive cytological diagnosis in patients with thyroid nodules is demonstrated in the findings of this study. Patients without a definitive cytological diagnosis pre-operatively were more likely to have a hemithyroidectomy as their primary procedure. Given the low complication rate, hemithyroidectomy per se is not a problem. However, this study also found that significantly more patients with indeterminate cytology required a completion thyroidectomy, and

Declaration of competing interest

There is no conflict of interest to declare.

Acknowledgements

We acknowledge the contribution of our multidisciplinary colleagues for the clinical care of the patients, and Dr M Yeung and A/Prof W Johnson for contribution of cases to the MUESU database. We would also like to thank our former database manager Ms Melissa Vereker for populating and maintaining the database.

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Citation Excerpt :
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^☆: Part of this study was presented by YJL at the Royal Australian College of Surgeons Annual Scientific Congress in 2015 & other parts were presented by RS in 2018. JCL was the recipient of the Royal Australasian College of Surgeons Senior Lecturer Fellowship in 2017 and 2018.

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Quantifying the differences in surgical management of patients with definitive and indeterminate thyroid nodule cytology☆

Abstract

Introduction

Materials and methods

Results

Conclusion

Introduction

Section snippets

Materials and Methods

Results

Discussion

Declaration of competing interest

Acknowledgements

Endocrinol Metab Clin N Am

Surgery

Endocr Pract

Lancet

Surgery

Eur J Surg Oncol

Clinical characteristics as predictors of malignancy in patients with indeterminate thyroid cytology: a meta-analysis

Endocrine

Cancer in Australia 2017

Cancer Series No. 101. Cat. No. CAN 100

Preoperative diagnosis of benign thyroid nodules with intermediate cytology

Gland Surg

Evaluation of the effect of diagnostic molecular testing on the surgical decision-making process for patients with thyroid nodules

JAMA Otolaryngol Head Neck Surg

American thyroid association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American thyroid association guidelines task force on thyroid nodules and differentiated thyroid cancer

Thyroid

The impact of synoptic cytology reporting on fine-needle aspiration cytology of thyroid nodules

ANZ J Surg

Thyroid ultrasound-guided fine-needle aspiration cytology results: observed increase in indeterminate rate over the past decade

Otolaryngol Head Neck Surg

Preoperative diagnosis of benign thyroid nodules with indeterminate cytology

N Engl J Med

A large multicenter correlation study of thyroid nodule cytopathology and histopathology

Thyroid

The Bethesda system for reporting thyroid cytopathology: a meta-analysis

Acta Cytol