Circulating Tumor Cells Correlate with Clinicopathological Features and Outcomes in Differentiated Thyroid Cancer.

Background/aims: As biomarkers, circulating tumor cells (CTCs) from solid tumors can predict metastases and prognoses, and help monitor treatment efficacy. However, conventional CellSearch methods have low sensitivity to differentiated thyroid cancer (DTC) CTCs. In this study, for the first time, we used negative enriching (NE) immunofluorescence-in situ hybridization (iFISH) of chromosome 8 to capture and identify CTCs in DTC patients; and investigated how CTCs correlate with clinicopathological factors and prognosis in DTC patients with distant metastases (DM).

Methods: In this prospective study, we enrolled 72 patients with DTC before they underwent 131I treatment, and 30 healthy controls (HC). Their CTCs were measured in 7.5 ml peripheral blood using the NE-iFISH technique. CTC was defined by the aneuploidy.

Results: We detected CTCs in 62 (86.1%) of the 72 subjects with DTC. The mean number of CTCs in patients with DTC with DM (DM+) was significantly higher than in the HC group (P< 0.001) and DTC patients without DM (DM-; P=0.0016). We found CTCs ≥ 5 was significantly associated with DM+ DTC (P=0.009; sensitivity: 64.3%; specificity: 83.8%); CTCs ≥ 7 was related to poor response to 131I treatment (sensitivity: 73.7 %; specificity: 69.6 %), and was also associated with worse prognosis in DM+ DTC (P< 0.001).

Conclusion: We found CTCs ≥ 5 to be a potential predictive index for DM+ DTC; and CTCs ≥7 as a possible indicator of poor response to 131I treatment and worse prognosis in DM+ DTC.