Detection of driver mutations in plasma cell-free nucleic acids in differentiated thyroid neoplasm.

IMPORTANCE: This proof-of-concept paper demonstrates that driver mutations can be detected in plasma in differentiated thyroid tumors, and we were able to detect mutations in upto 80% malignant thyroid nodules. Additionally, cancer subtypes could also be predicted using a 8-gene panel. In almost 90% follicular adenoma, rat sarcoma virus (RAS) mutations were detectable. There was a strong agreement between driver mutations found in plasma samples, FNAC materials, and histopathology samples. This has potential as a noninvasive, preoperative diagnostic tool (particularly of clinical importance in indeterminate nodules) and may help in detection of residual tumor after surgery. Future research is warranted to test the role of this tool to detect tumor recurrence.

OBJECTIVE: Ultrasonographic (USG) evaluation and fine-needle aspiration (FNA) are cornerstone for evaluation of thyroid neoplasm. Molecular technique including detection of driver mutation from FNA cytology (FNAC) material is an established modality. In this study, we explored the feasibility of using plasma cell-free nucleic acids to identify known driver mutations in differentiated thyroid neoplasm.

DESIGN: Patients presenting with thyroid nodules underwent USG with Thyroid Image Reporting and Data Systems scoring and FNAC (Bethesda classification). All patients in Bethesda 3, 4, 5, 6 underwent surgery and histopathological confirmation. Patients in Bethesda 2 (cosmetic concerns, compressive symptoms) underwent surgery, and rest were presumed benign on the basis of USG, FNAC features, and clinical followup.).

SETTING: Endocrinology clinic.

PARTICIPANTS: Subjects with thyroid nodule.

INTERVENTION(S) OR EXPOSURE(S): None.

MAIN OUTCOME(S) AND MEASURE(S): Plasma sample, FNA, and histopathology material were evaluated for driver mutations (8-gene panel comprising BRAF-V600E, RET/PTC3, RET/PTC1, TERT promoter, HRAS, NRAS, KRAS, and PAX8-PPARG).

RESULTS: A total of 223 subjects were recruited; of these 154 were benign and 69 had differentiated thyroid cancer. We were able to detect driver mutation from plasma in 55 subjects (79.71%) of all malignant patients, and 11 patients in benign category had RAS mutation (follicular adenoma). Rest of the benign nodules did not have any detectable driver mutations.

CONCLUSIONS AND RELEVANCE: Plasma might be a viable noninvasive alternative source for detection of driver mutations (8-gene panel) in subjects with differentiated thyroid tumors and may have significant clinical utility.