Monitoring epithelial, epithelial-mesenchymal, and mesenchymal circulating tumor cells on papillary thyroid cancer following thyroidectomy: A prospective cohort study.

Abstract

6097 Background: Monitoring the effectiveness of cancer-removal surgery is challenging in most cases. Therefore, robust and non-invasive techniques have been developed, and liquid biopsy is an apparent method for that purpose. In this prospective cohort study, we examined whether one type of liquid biopsy, an enumeration of circulating tumor cells (CTCs), can monitor the effectiveness of thyroidectomy in patients with papillary thyroid cancer (PTC). Methods: From January 2021 to January 2022, we recruited 62 PTC patients who had operated on isthmectomy, lobectomy, and total thyroidectomy for this study at Seoul National University Bundang Hospital. The blood samples from the recruited patients were collected before surgery and two weeks and three months after the surgery for CTC detection. We collected peripheral blood samples by venipuncture from each patient in EDTA tubes and stored them at 4°C until isolation and characterization of CTCs (within 6 hours). Results: We found the CTCs in 87% (54/62) of PTC patients, with an average number of 8.0. This number significantly decreased after thyroidectomy, with an average of 5.3 and 4.3 post-operation of two weeks and three months, respectively. In the peripheral blood of PTC patients, the CTCs with epithelial-mesenchymal and mesenchymal phenotypes were significantly more frequent than the epithelial phenotype of CTCs. Furthermore, PTC patients with lymphatic invasion, lymph node metastasis, or BRAF V600E mutation showed significantly decreased CTC count after surgery. Conclusions: PTC patients had a significantly higher number of CTCs undergoing epithelial-mesenchymal transition and showed a significant decrease in CTC count after surgery. This indicates that liquid biopsy using CTC enumeration can satisfy the purpose of monitoring the effectiveness of cancer-removal surgery. Clinical trial information: KCT0008179.