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AUSTIN -- Repeat fine needle aspiration (FNA) allowed most cases of thyroid nodules initially identified as atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) to be reclassified, researchers reported here.

The systematic review and meta-analysis showed that 55% of thyroid nodules with AUS/FLUS cytology were identified as benign following repeat FNA, according to Cesar Abuchaibe, MD, of University of South Florida, and colleagues.

Just 6% of thyroid nodules with AUS/FLUS cytology were reclassified as malignant or suspicious for malignancy following repeat FNA, according to the report presented at the American Association of Clinical Endocrinologists' 2017 meeting.

The American Thyroid Association's 2015 guidelines recommend against repeating the biopsy for the management of patients with thyroid nodules. Instead, the current guidelines suggest molecular marker testing as an alternative. This updated recommendation was centered on the available literature, which supported the validity of molecular marker testing. It indicated that repeat biopsy may yield unreliable results.

"The only reference that the ATA guidelines gave for this recommendations is based on one single retrospective study from 2011," Abuchaibe explained during an oral presentation.

Prior to this revision in recommendations, Abuchaibe's group noted that it was commonplace to conduct repeat FNA cytology on thyroid nodules initially diagnosed as AUS/FLUS. For this reason, their goal was to "clarify the outcomes" regarding repeat FNA.

Abuchaibe's group gathered 1,846 articles from databases searches, narrowing them down to 27 studies included in the final analysis. Of these, 17 contained surgical follow-up information and therefore were used in the malignancy prevalence assessment.

Among the studies included, a total of 4,376 thyroid nodules underwent repeat FNA., originally identified as Bethesda III, according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In addition to showing that 55% of reexamined nodules were found to be benign, the analysis showed that about one-fourth of the total nodules remained AUS/FLUS (26%, 1,122). Additionally, 8% were reclassified as follicular/Hürthle-cell neoplasm (340), 6% were non-diagnostic (242), 4% were identified as suspicious for malignancy (181), and 2% were malignant (80).

Some nodules resected after repeat FNA were assessed -- a total of 1,288 cases -- and the authors reported a 23% overall prevalence of malignancy (293). Among nodules classified as malignant on repeat FNA, pathologic examination of resected specimens showed a 100% prevalence of malignancy (28 of 28), as well as malignancy prevalence of 71% for those classified as suspicious for malignancy (63 of 93). For follicular/Hürthle-cell neoplasm resected nodules, the authors reported a 38% prevalence of malignancy (66 of 175), as well as a 24% prevalence for AUS/FLUS nodules (115 of 475). "Benign" resected nodules had a 2% malignancy prevalence (9 of 481), and 30% of non-diagnostic nodules were found to be malignant (10 of 35).

Abuchaibe's group reported an overall negative predictive value of 98% for repeat fine needle aspiration. Because the repeat FNA findings were so notable, the authors concluded that this method was more cost-effective than the currently recommended molecular marker tests. "The only difference in this case for the negative predictor value is the cost. The cost of the molecular marker [tests] is fourfold that of the repeat biopsy," Abuchaibe explained.

Additional studies are recommended to further compare the two methods in terms of the reassessment of AUS/FLUS thyroid nodules.

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