Abstract:

Objective Large-scale clinical studies on malignant rhabdoid tumor (MRT) in Chinese pediatric populations remain limited, with existing literature predominantly restricted to single anatomic subtypes. Systematic comparative analyses encompassing all three subtypes—malignant rhabdoid tumor of the kidney (MRTK), atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system, and extrarenal extracranial rhabdoid tumor (EERT)—are notably lacking, and prognostic stratification systems await further refinement. This retrospective study aims to characterize the clinicopathological features and treatment responses of these three anatomic subtypes (AT/RT, MRTK, and EERT) in children with MRT, and to identify independent prognostic factors, thereby providing evidence-based insights for clinical risk stratification and individualized therapeutic decision-making. Methods A retrospective analysis was conducted on the clinical data of children with MRT admitted to the hospital from July 2017 to July 2024, including gender, age at onset, serum lactate dehydrogenase (LDH) level at initial diagnosis, tumor location, metastasis status at initial diagnosis, immunohistochemical test results of tumor tissue, treatment methods, and follow-up outcomes. The Kaplan-Meier method was used to calculate the overall survival (OS) rate and progression-free survival (PFS) rate, and the COX regression model was used to analyze the impact of different factors on OS. Results A total of 50 pediatric patients with MRT were enrolled, comprising 18 with AT/RT, 17 with MRTK, and 15 with EERT. The male-to-female ratio was 21:29. The median onset age of 50 patients was 27.0 (14.25-52.25) months, among whom 38 patients (76.0%) developed the disease before the age of 3. At the time of initial diagnosis, 26 children (52.0%) presented with local or distant metastasis, and 15 (30.0%) had abnormally elevated LDH levels. The immunohistochemical results of tumor tissues indicated that all 50 children had a loss of SMARCB1 (INI1) protein. Forty-nine children (98.0%) received surgical treatment before chemotherapy, among whom 34 children had complete resection, 15 had partial resection, and 1 only underwent fine-needle aspiration biopsy. All 50 children received multi-drug combined chemotherapy, and 27 (54.0%) received radiotherapy. There was a statistically significant difference in the radiotherapy rate among the AT/RT group, MRTK group, and EERT group (P<0.05), with the ATRT group having a higher radiotherapy rate. Thirty-two (64.0%) children achieved partial remission or complete remission after the induction chemotherapy, while the remaining 18 children showed stable disease or progression of disease. The main adverse reactions during chemotherapy included bone marrow suppression, infection, and abnormal liver function. The follow-up was conducted until December 2024, with a median follow-up time of 24 months (ranging from 3 to 84 months). Kaplan-Meier survival analysis showed that the 3-year OS rate of all children was 51.5% (95%CI: 35.2%-67.8%), and the 3-year PFS rate was 50.6% (95%CI: 33.4%-67.8%). There was no statistically significant difference in the 3-year OS rate and PFS rate among the AT/RT, MRTK and EERT groups of children (P>0.05). Multivariate COX regression analysis showed that concurrent metastasis at the initial diagnosis, abnormally elevated LDH levels, and incomplete surgical resection were independent risk factors for poor prognosis (P<0.05). Conclusions The overall prognosis of pediatric MRT remains poor. No significant differences were observed in clinical characteristics or survival outcomes among the three subtypes, although a higher proportion of patients with AT/RT received radiotherapy. Complete surgical resection, normal baseline LDH level, and absence of metastasis at initial diagnosis were identified as independent favorable prognostic factors. These findings underscore the necessity of implementing multidisciplinary comprehensive treatment based on early risk stratification to improve clinical outcomes.

Key words: malignant rhabdoid tumor, chemotherapy, radiotherapy, prognosis, child