Abstract
The objective of this meta-analysis was to evaluate the performance of the Gene Expression Classifier (GEC) and ThyroSeq v2 (ThyroSeq) in the preoperative diagnosis of thyroid nodules with indeterminate fine-needle aspiration biopsy results. We searched literature databases from January 2001 to April 2018. The bivariate model analysis was performed to estimate pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR−), positive predictive value (PPV), and negative predictive value (NPV). Pooled data from 1086 nodules with histopathologic confirmation from 16 GEC studies enabled calculation of diagnostic parameters (95% confidence interval): sensitivity 98% (96–99%), specificity 12% (8–20%), PPV 45% (37–53%), and NPV 91% (85–96%). Pooled data from five ThyroSeq studies assessing 459 nodules showed sensitivity of 84% (74–91%), specificity 78% (50–92%), PPV 58% (31–81%), and NPV 93% (89–97%). When both tools were compared, GEC had a significantly higher sensitivity (p = 0.003), while ThyroSeq had a significantly higher specificity (p < 0.001) and accuracy (p = 0.015). Pooled LR+ was higher for ThyroSeq: 3.79 (1.40–10.27) vs. 1.12 (1.05–1.20). Pooled LR− was higher for GEC, 0.20 (0.10–0.39) vs. 0.13 (0.05–0.31). The bivariate summary estimates of sensitivity and specificity for GEC and ThyroSeq and their pooled accuracy showed a superiority of the ThyroSeq test. The GEC with a high sensitivity and NPV may be helpful in ruling out malignancy in cases of indeterminate thyroid nodule cytology. ThyroSeq has a significantly higher specificity and accuracy with an acceptable sensitivity so that it has the potential for use as an all-round test of malignancy of thyroid nodules.
Highlights
Up to 35% of fine-needle biopsy (FNB) procedures on thyroid nodules produce an indeterminate result [1, 2], which includeBethesda classification categories III and IV: atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) or follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) [2]
Relevant data included articles comparing the number of malignant and benign nodules with the conclusive histopathological result in a group of benign and suspicious changes according to Gene Expression Classifier (GEC), previously assessed as Bethesda categories III and IV in thyroid FNB or positive changes according to ThyroSeq were included in the meta-analysis
The value of LR− was similar for both methods and diagnostic odds ratio (DOR) was slightly higher for ThyroSeq
Summary
Up to 35% of fine-needle biopsy (FNB) procedures on thyroid nodules produce an indeterminate result [1, 2], which includeBethesda classification categories III and IV: atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) or follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) [2]. Most patients with indeterminate FNB results, especially those with malignant features in the USA [3] are referred for surgery. The malignancy rate in indeterminate nodules is reported between 15 and 54% [1, 2]. This means that many patients with indeterminate cytological results are exposed to potentially unnecessary surgery with the associated increased risks of mortality and complications. The 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer recommends the use of molecular testing to support malignancy risk assessment in thyroid nodules with indeterminate cytology results [3]. The two most common genetic tests used as preoperative molecular markers
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