Predictive Value of microRNA in Thyroid Cytologies of Undetermined Type

Morphological analysis of fine-needle aspiration cytology (FNAC) under ultrasound classifies thyroid nodules in 6 categories (Bethesda classification). The diagnostic approach is codified by the Society of Endocrinology and for cytologies of indeterminate type (Bethesda 3, 4 and 5), surgery of thyroid nodules is currently recommended. However, only 15.9% of the cytologies classified Bethesda 3, 26.1% of the Bethesda IV and 75.2% of the Bethesda V are actually cancers in the definitive histological analysis on surgical resection.

Thus, new tools for predicting the risk of thyroid nodule malignancy need to be developed.

To date, various risk stratification biomarkers have been reported in the literature but have not been validated in independent cohorts, thus excluding their implementation in daily practice.

In addition, two commercial nucleic acid tests are proposed at a cost not compatible with generalized diffusion. The first approach is based on a next generation sequencing analysis of a target gene panel at the nucleotide sequence or transcribed level. The second alternative combines an analysis at level 1) of the deoxyribonucleic acid (DNA) with the search for somatic variations such as mutations in oncogenes or the presence of fusion genes, and 2) microRNA with the measurement of their level of expression.

Due to their stability, their ability to modulate the expression of various messenger RNA, microRNA are an attractive line of research.

The aim is to validate a signature of microRNA based in a first exploratory study allowing the stratification of the cytologies of indeterminate type and to study and select others. In a first step, the teams will focus on standardising the pre-analytical stages and defining a threshold of positivity. The results of microRNA signature on a cohort of 70 patients will be compared with the ultrasound and then histological data of the resection specimen.