Significance of circulating tumor cells in osteosarcoma patients treated by neoadjuvant chemotherapy and surgery

PURPOSE: By examining and identifying circulating tumor cell (CTC) counts and subtypes of peripheral blood in osteosarcoma patients, we evaluated the relationship between CTCs and characteristics of osteosarcoma patients, as well as CTC changes after neoadjuvant chemotherapy and surgery. METHODS: CanPatrol™ CTC technology was used to detect CTCs in peripheral blood before and after treatment in 32 osteosarcoma patients. Peripheral blood samples from 10 healthy volunteers were included as controls and examined for the presence of CTCs. RESULTS: Of the 32 osteosarcoma patients, CTCs were detected in 30 patients before treatment, and the average CTC count was 14.06±9.08. No CTCs were detected in the 10 healthy volunteers. The detected CTCs were divided into epithelial CTCs, mesenchymal CTCs (M-CTCs), and biophenotypic epithelial/mesenchymal CTCs. The average number of pretreatment CTCs was higher in stage III patients than in stage IIB patients (P=0.012). Twenty-eight patients were screened for changes in CTC count at 1 week after neoadjuvant chemotherapy and at 4 weeks after surgery. We divided these 28 patients into two groups according to the changes in the percentage of M-CTCs before and after treatment, and the results showed that the disease-free survival (DFS) was significantly shorter in the M-CTC percentage-increased group than in the M-CTC percentage-decreased or no-change group (P=0.032). Five patients with stage II osteosarcoma were examined for CTCs at the appearance of lung metastases, and the total number of CTCs was found to be higher at the appearance of lung metastases than before treatment in these patients. CONCLUSION: The rate of presence of CTCs in the peripheral blood of osteosarcoma patients is high, and patients with an increased percentage of M-CTCs after treatment have a shorter DFS. The dynamic monitoring of changes in CTC counts after treatment has clinical significance for the timely detection of recurrence or metastasis.