Core-Needle Biopsy Does Not Show Superior Diagnostic Performance to Fine-Needle Aspiration for Diagnosing Thyroid Nodules

Abstract

Purpose: To compare the diagnostic performances of fine-needle aspiration (FNA) and core-needle biopsy (CNB) for thyroid nodules according to nodule size. Materials and Methods: This retrospective study included 320 thyroid nodules from 320 patients who underwent both FNA and CNB at outside clinics and proceeded with surgery in our institution between July 2012 and May 2019. According to nodule size, the diagnostic performances of FNA and CNB were calculated using various combinations of test-negatives and test-positives defined by the Bethesda categories and were compared using the generalized estimated equation and the Delong method. Results: There were 279 malignant nodules in 279 patients and 41 benign nodules in 41 patients. The diagnostic performance of FNA was mostly not different from CNB regardless of nodule size, except for negative predictive value, which was better for FNA than CNB when applying Criteria 1 and 2. When applying Criteria 3, the specificity and positive predictive value of FNA were superior to CNB regardless of size. When applying Criteria 4, diagnostic performance did not differ between FNA and CNB regardless of size. After applying Criteria 5, diagnostic performance did not differ between FNA and CNB in nodules ≥2 cm. However, in nodules ≥1 cm and all nodules, the sensitivity, accuracy, and negative predictive value of CNB were better than those of FNA. Conclusion: CNB did not show superior diagnostic performance to FNA for diagnosing thyroid nodules.

Factors to Consider When Interpreting the Diagnostic Performance of Fine-Needle Aspiration and Core-Needle Biopsy in a Specific Study Population

“…Previous studies involving similar head-to-head comparisons have consistently shown that compared to FNA, CNB has a higher sensitivity and similar specificity for diagnosing thyroid malignancy in the general patient population with first-line or second-line CNB. 3 8 9 In the study by Shin, et al, 1 CNB showed a significantly higher sensitivity with criteria 3 (criteria for therapeutic and diagnostic surgery) and criteria 5 (criteria for therapeutic surgery) and a marginally higher sensitivity with criteria 4 for malignancy than FNA in the entire study population. Further, CNB showed a higher sensitivity than FNA with criteria 5 in the subgroup patients with nodules ≥1 cm.…”

“… 4 When surgery is used as the gold standard for diagnosing thyroid nodules, many true negative benign nodules without surgical diagnosis are inevitably excluded from the study population, and the specificity is lowered due to partial verification bias. 5 In the study by Shin, et al, 1 the malignancy rate of benign CNB results was extraordinarily high [CNB, 87.5% (7/8); FNA, 33.3% (6/18)], which is markedly different from the true malignancy rate (<3%) in nodules with benign FNA 6 and CNB 7 results in the general patient population. Therefore, the estimated specificities in this specific study population may not be generalizable to real-world clinical practice.…”

“…We read with great interest the article by Shin, et al 1 comparing the diagnostic performance of fine-needle aspiration (FNA) and core needle biopsy (CNB). This head-to-head comparison in a specific patient population revealed that CNB is not superior to FNA for diagnosing thyroid nodules, which is inconsistent with the result reported by a previous study involving similar head-to-head comparisons in the general patient population.…”

“…Several factors should be considered when interpreting the results reported by Shin, et al 1 First, the study population included a specific group of referred patients who underwent both FNA and CNB at other clinics and underwent surgery (the gold standard for diagnosing thyroid nodules in the study) at the authors' institution. The disease spectrum in the specific study population may not be representative of patients in general clinical practice, as the prevalence of malignant tumors was very high (87.2%), compared to the real-world prevalence of malignant tumors in patients undergoing biopsy for thyroid nodules in clinical practice (approximately 10–20%).…”

“…Second, the pathologic classification of CNB diagnostic results into six diagnostic categories highly depends on the experience of a pathologist in reading CNB samples according to the pathological diagnostic criteria for CNB. In the study by Shin, et al, 1 the CNB pathologic reports were categorized into six categories based on the Bethesda System by a radiologist, and therefore, it is uncertain whether CNB diagnostic results, except the definitively benign or malignant results, were accurately categorized according to the pathological diagnostic criteria of CNB.…”