Potential clinical value of circulating tumor cells in predicting progression for atypical teratoid rhabdoid tumor in young children

Atypical teratoid rhabdoid tumor (ATRT) is a rare pediatric brain tumor characterized by an extremely poor prognosis despite receiving comprehensive treatments. Circulating tumor cells (CTCs) detection has high clinical value in the prediction of the progression of malignant solid tumors and the evaluation of treatment effects. However, very few studies have focused on CTCs in pediatric CNS embryonal tumors especially ATRT. This study aims to evaluate and compare the feasibility of detecting CTCs in young children with ATRT, and to analyze the clinical value of CTCs count in monitoring ATRT tumor progression. Young children under 3 years old who were diagnosed with ATRT and performed maintenance treatment from July 2023 to June 2024 after comprehensive therapy in our institution were enrolled. CTCs count both in cerebrospinal fluid (CSF) and peripheral blood were separately calculated based on two morphological types: CTC and tumor-derived circulating hybrid cells (CHC). Area under the receiver operating characteristic (ROC) curves (AUC) were used to determine the threshold of CTCs in predicting tumor progression. Kappa coefficients were applied to assess consistency between MRI scans, CSF cytology and CTCs by using progressive disease (PD) outcomes as the reference. CTCs count in 34 blood samples and 34 CSF samples, as well as the results of CSF cytology examination and MRI scans in simultaneous period, were collected from six pediatric patients. When the progressive disease (PD) outcomes were used as a reference, CSF cytology test had a higher false negative rate compared with MRI scans (37.5% vs. 8.3%). In CSF, the sum of CTC + CHC had the highest significant diagnostic efficacy (AUC = 0.771, p = 0.001, Accuracy = 73.5%) with a cut-off value of 2.5. All of CSF-CTCs had statistically significant consistency with PD outcomes. In peripheral blood, all of CTCs had insignificant diagnostic efficacy. However, the sum of CTC + CHC had statistically significant consistency with PD outcomes (Kappa value = 0.406, p = 0.024), with a negative prediction cut-off value of 65 (AUC = 0.397, p = 0.371, Accuracy = 76.5%). CTCs in CSF and peripheral blood can both be detected in young-age ATRT patients after receiving comprehensive treatment. CTCs have considerable clinical predictive value in monitoring the progression of ATRT.