Some primary bone tumors are prone to hematogenous metastasis and after that, the therapeutic effect is not that good and prognosis is poor. Circulating tumor cells (CTC) shed from the tumor cells of primary or metastatic focus and then enter into blood circulation. CTC may appear in the early stage of the tumor, which can implant in distant organs to form metastatic sites and self-implant in the primary sites leading to the tumor recurrence; CTC are closely related with the prognosis of patients with tumors. In most primary bone tumors, CTC are heterogeneous compared with primary tumor cells. Studying CTC from various aspects can provide a basis for the early diagnosis and treatment of primary bone tumors. This review summarizes the current researches of CTC in common primary bone tumors, and expects the future of research direction and application practice in clinic.

Objective:To investigate the predictive value of Doppler ultrasonography combined with cytokeratin fragment 19 (Cyfra21-1) and soluble interleukin-2 receptor (sIL-2R) in cervical lymph node metastasis of thyroid micropapillary carcinoma.Methods:102 patients with minimal papillary carcinoma of thyroid confirmed by surgery and pathology admitted to Ultrasound Department, Shanxi Cancer Hospital from Aug. 2020 to Aug. 2023 were selected and treated with thyroidectomy plus central region and at least one cervical lymph node dissection. Among them, There were 24 cases in the LLNM group and 78 cases in the non-LLNM group.Results:There were significant differences in age, shape, nodular and capsule contact area, tumor shape aspect ratio > 1, blood flow, microcalcification, serum Cyfra21-1 and serum sIL-2R levels between the two groups (Cyfra21-1: P<0.001, sIL-2R: P=0.001). Logistic regression analysis showed that age ≥50 years old ( OR=0.443, 95% CI: 0.217-0.904), microcalcification ( OR=2.787, 95% CI: 1.491-5.208), Cyfra21-1>3.3ng/ml ( OR=3.117, 95% CI: 1.404-6.922) and sIL-2R > 110.45pmol/L ( OR=3.408, 95% CI: 1.473-7.884) were independent risk factors for cervical lymph node metastasis in PTMC patients ( P < 0.05). The ROC curve results showed that the area under the curve of cervical lymph node metastasis predicted by Doppler ultrasound combined with Cyfra21-1 and sIL-2R was 0.82, and the sensitivity and specificity were 83.67% and 70.56%, respectively. Conclusions:The calcification features of Doppler ultrasound and the elevation of serum Cyfra21-1 and sIL-2R are closely related to cervical lymph node metastasis of thyroid micropapillary carcinoma. The combination of Doppler ultrasound with serum Cyfra21-1 and sIL-2R has important reference value in predicting cervical lymph node metastasis.