Molecular Insights into Thyroid Cytopathology Diagnoses – Working to Improve Indeterminate Diagnoses

A study published by teams from the UPMC Department of Pathology, the Division of Endocrine Surgery, and the Division of Endocrinology and Metabolism examined the effectiveness of molecular-derived risk of malignancy (MDROM) and positive call rate (PCR) in assessing indeterminate thyroid cytopathology diagnoses.

Faculty from the Division of Endocrinology and Metabolism include Esra Karslioglu-French MD, Elena M. Morariu MD, and Jagdeesh Ullal, MD.

The research analyzed diagnostic data over a two-year period from a cohort of cytopathologists and from corresponding ThyroSeq v3 test results across different cytopathologic categories and compared MDROMs and PCRs with traditional risk of malignancy (ROM) metrics. The findings from the study suggest that while individual cytopathologists' MDROMs generally align with reference ROMs, PCRs more distinctly highlight differences in ROM performance. This approach offers personalized feedback and could aid in quality improvement in thyroid cancer diagnostics.

The study was published online ahead of print in October 2023 in Cancer Cytopathology. N. Paul Ohori, MD, from the Department of Pathology was the study’s lead author.

What is ThyroSeq v3?

The ThyroSeq v3 test is an advanced genomic classifier developed by teams at the University of Pittsburgh and UPMC, led by Yuri E. Nikiforov, MD, PhD. The ThyroSeq test represents a significant advancement in thyroid cancer diagnostics. The test utilizes next-generation sequencing technology to analyze thyroid nodule fine-needle aspiration samples for a comprehensive panel of genetic alterations, including mutations and gene fusions known to be associated with thyroid cancer. The ThyroSeq v3 test helps clinicians in distinguishing benign thyroid nodules from those that are malignant or suspicious for malignancy, providing clinicians with important data to aid in decisions regarding patient management, particularly in cases of indeterminate thyroid cytology. ThyroSeq has been used at UPMC since 2017 and Dr. Nikiforov and colleagues have published numerous studies on its development, implementation, and efficacy in clinical practice since it was first deployed.

Study Overview, Findings, and Implications for Clinical Care

The research focused on indeterminate thyroid cytopathology diagnoses - specifically atypia of undetermined significance (AUS), follicular neoplasia (FN), and follicular neoplasia, oncocytic-type (ONC). Diagnostic data was analyzed from cases worked on by seven cytopathologists.

“If we can improve accuracy in diagnosis, it is a win-win,” says Dr. Ullal. “We can improve our risk stratification for patients, attain more accurate diagnoses, and reduce the number of unnecessary surgical resections.”

A significant variation was observed in the MDROM across different diagnoses. For AUS, FN, and ONC, the MDROMs showed a broad range. Specifically, for AUS, MDROMs were recorded found to be between 5.8% and 20.8%, for FN the range was between 22.1% and 36.7%, and for ONC diagnoses, the range was 19.5% to 41.5%. Notably, most of these MDROMs fell within the expected ROM ranges as defined by the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) guidelines that are widely used in the field.

Another finding from the study was related to the analysis of PCR, particularly in the AUS category, where differences were observed within the cytopathologist cohort examined in the investigation. This variation in PCR highlights its potential utility in distinguishing differences in ROM performance across diagnosticians.

“PCR could be a valuable metric in evaluating the accuracy and consistency of cytopathologists in diagnosing thyroid lesions,” says Dr. Ullal.

The study also highlights some of the limitations of traditional cytologic-histologic correlation in estimating ROM. This correlation often involves only a subset of cases that undergo surgical resection, which may lead to an overestimation of ROM.

In contrast, MDROMs may provide a more inclusive view by considering both resected and unresected cases, offering a broader perspective on the risk associated with thyroid lesions.

The clinical implications of the study’s findings are important in a number of ways. The introduction of MDROMs and PCRs as evaluative tools could lead to a significant shift in the approach to thyroid cytopathology. These molecular-centric metrics provide a more comprehensive and personalized assessment of cytopathologist performance, potentially influencing clinical decision-making.

“In particular, when it comes to dealing with indeterminate diagnoses, a clearer understanding of individual cytopathologists' diagnostic patterns could lead to more tailored and precise patient care when evaluating the potential existence of thyroid cancer,” says Dr. Ullal.”

Reference

Ohori PN, Cuda JM, Bastacky SI, Yip L, Karslioglu-French E, Morariu EM, Ullal J, Ramonell KM, Carty SE, Nikiforov YE, Schoedel KE, Seethala RR. Molecular-Derived Risk of Malignancy and the Related Positive Call Rate of Indeterminate Thyroid Cytology Diagnoses as Quality Metrics for Individual Cytopathologists. Cancer Cytopathol. 2023; October 17. Online ahead of print.