Fine needle aspiration cytology, a diagnostic test central to thyroid nodule management, may yield indeterminate results in up to 30% of cases. A high proportion of these patients are subjected to diagnostic surgery, but only a minority of resected indeterminate thyroid nodules are histologically diagnosed as malignant.
In this clinical setting, molecular markers may be useful as diagnostic tools, complementing and integrating the information provided by cytology and improving preoperative risk stratification for indeterminate nodules.
We recently developed a dual-component assay that involves NGS-based detection of mutations and dPCR evaluation of the expression levels of an microRNA strongly associated with thyroid cancer. This assay offered some advantages over the currently available tests, including a relatively low number of molecular markers, which translates into lower overall testing costs, the employment of high-sensitivity methods. And finally, it offers higher performance in term of sensitivity and NPV. Despite the high performance, much effort should be done specially to increase positive predictive value in some tumor subtypes (i.e., in RAS-mutated cases, which encompass both benign and tumor cases).
Here we plan to further improve clinical performance of the assay by including a third molecular component based on the Raman spectroscopy (RS). RS spectra provide fingerprint information on biological structures of the analyzed samples and were already used to integrate the traditional tools used for cancer diagnosis. We demonstrated that RS technique is effective in discriminating benign from malignant thyroid tissues and it can be applied also to thyroid aspirates.
The integration of data from the three molecular assays with clinical, sonographic and morphological data has great potential to improve the diagnostic accuracy of cytology and personalize management of thyroid cancer patients thus reducing unnecessary surgery and health care costs.
Fine needle aspiration (FNA) cytology, a diagnostic test central to thyroid nodule management, may yield indeterminate results in up to 30% of cases. Deciding whether patients with a cytologically indeterminate thyroid nodule should be referred for surgery or for active surveillance is an important challenge for clinicians.
Several approaches have been proposed to improve diagnostic workup of indeterminate nodules, including sonographic risk stratification systems, elastosonography, their combination. In a significant number of cases of this type, the decision is made to schedule diagnostic surgery, based on a probability of malignancy ranging from 15 to 40%. However, only the 25% of these resected nodules are diagnosed cancer. This means that¿aside from the impact of this practice in terms of healthcare spending¿most indeterminate thyroid nodules are currently being over-treated and the patients harboring them are being unnecessarily exposed to surgical risks (i.e., recurrent laryngeal nerve injury, hypocalcemia, hemorrhage/hematoma, hypothyroidism).
A preoperative test that could reliably exclude malignancy would be a valuable aid for choosing an optimal management strategy, in particular for supporting a recommendation for deferring surgery (and possibly avoiding it altogether).
In the last decade, a variety of molecular tests have been marketed as reliable aids for increasing the accuracy of preoperative diagnosis of indeterminate lesions. Four molecular tests have been developed in United States and are now commercially available there for evaluation of thyroid FNA samples: the Afirma Genomic Sequencing Classifiers, the ThyroSeq v.3 Genomic Classifier, the ThyGeNEXT® /ThyraMIR¿, and Rosetta GX Reveal. Although their goals are the same, these tests vary substantially from one another in terms of the molecular markers they target (mutations, mRNA, or microRNA expression), the underlying methodology (NGS, castPCR, RT-qPCR), the type of samples (same as those initially used for cytological diagnosis or additional samples), and, last but not least, their diagnostic performance.
We recently developed a dual-component assay that involves NGS- based detection of mutations and dPCR evaluation of the expression levels of an microRNA strongly associated with thyroid cancer. This assay offered some advantages over the currently available tests mentioned above, including a relatively low number of molecular markers, which translates into lower overall testing costs, the employment of high-sensitivity methods for both mutation detection and assessment of miRNA expression levels. And last but not least, it offers high performance, with sensitivity and NPV higher than those of the currently available tests mentioned above. Despite the high performance, much effort should be done specially to increase positive predictive value in some tumor subtypes (i.e., in RAS-mutated cases, which encompass both benign and tumor cases).
Here we plan to further improve clinical performance of the assay by including a third molecular component based on the Raman spectroscopy (RS) technique. RS spectra provide fingerprint information on biological structures of the analyzed samples and may be used to integrate the traditional tools used for cancer diagnosis. Our preliminary data demonstrate that RS technique is suited and effective in discriminating benign from malignant thyroid tissues and we have demonstrated its applicability also to thyroid cells aspirated by FNA.
The novel triple-combined molecular approach proposed in this project responds to the clinical needs to get a correct diagnosis of thyroid lesion, especially the follicular patterned ones, before the surgical treatment. This is a very critical field in endocrine neoplasms since currently thyroid cytology is not able to differentiate benign from malignant follicular lesions.
The integration of data from the three molecular assays (NGS, dPCR and Raman) applied on the same FNA sample with clinical, sonographic and morphological data has great potential to improve the diagnostic accuracy of cytology and personalize management of thyroid cancer patients thus reducing unnecessary surgery and tailoring its extension with benefits in prognostication, quality of life and lower health costs.