Survival benefit of postoperative radiotherapy for pediatric patients with primary intracranial atypical teratoid/rhabdoid tumors: Propensity score analysis and prediction model construction in a multi-registry based cohort

BACKGROUND

The role of postoperative radiotherapy (PORT) in children with primary intracranial atypical teratoid/rhabdoid tumor (AT/RT) remains controversial, and real-world data with large sample size are still lacking. This study aims to estimate the survival benefit of PORT in pediatric patients with resected AT/RT.

METHODS

Using Seer database, we collected 246 eligible intracranial AT/RT patients diagnosed between 2000 and 2016 for our analysis. Propensity score matching (PSM) analysis was employed to minimize selection bias for evaluation of the PORT efficacy. Multivariate Cox regression was conducted to determine the factors related to the outcome. Interaction tests were further performed between PORT and the prognostic variables. After identifying the significant prognostic factors, we further developed a novel prediction model to predict the life expectancy of these patients, as well as the potential benefit from PORT.

RESULTS

We found that PORT was significantly related to the improved survival after adjusting for other prognosticators in both the entire and PSM-matched cohort. Significant interactions of PORT with age at diagnosis and tumor extension were also observed. On basis of the prognostic indictors identified by L1-penalized lasso Cox regression analysis, a novel nomogram model was successfully established and externally validated.

CONCLUSION

Our study indicated that PORT was significantly associated with the improved survival in pediatric AT/RT patients, and the greater survival benefit from PORT could be achieved in patients <3 years old or with locoregional tumors. The novel prediction model was developed to provide help in clinical practice and in the design of related trials.

Embryonal Tumors of the Central Nervous System with Multilayered Rosettes and Atypical Teratoid/Rhabdoid Tumors

The 2016 WHO classification of tumors of the central nervous system affected importantly the group of CNS embryonal tumors. Molecular analysis on methylome, genome, and transcriptome levels allowed better classification, identification of specific molecular hallmarks of the different subtypes of CNS embryonal tumors, and their more precise diagnosis. Routine application of appropriate molecular testing and standardized reporting are of pivotal importance for adequate prognosis and treatment, but also for epidemiology studies and search for efficient targeted therapies. As a result of this approach, the term primitive neuroectodermal tumor-PNET was removed and a new clinic-pathological entity was introduced-Embryonal tumor with multilayered rosettes (ETMR). The group of CNS embryonal tumors include also medulloblastoma, medulloepithelioma, CNS neuroblastoma, CNS ganglioneuroblastoma, atypical teratoid/rhabdoid tumor (ATRT) and their subtypes. This chapter will focus mainly on ETMR and ATRT. Embryonal tumors with multilayered rosettes and the atypical teratoid/rhabdoid tumors are undifferentiated or poorly differentiated tumors of the nervous system that originate from primitive brain cells, develop exclusively in childhood or adolescence, and are characterized by a high degree of malignancy, aggressive evolution and a tendency to metastasize to the cerebrospinal fluid. Their clinical presentation is similar to other malignant, intracranial, neoplastic lesions and depends mainly on the localization of the tumor, the rise of the intracranial pressure, and eventually the obstruction of the cerebrospinal fluid pathways. The MRI image characteristics of these tumors are largely overlappingintra-axial, hypercellular, heterogeneous tumors, frequently with intratumoral necrosis and/or hemorrhages. Treatment options for ETMR and ATRT are very restricted. Surgery can seldom achieve radical excision. The rarity of the disease hampers the establishment of a chemotherapy protocol and the usual age of the patients limits severely the application of radiotherapy as a therapeutic option. Consequently, the prognosis of these undifferentiated, malignant, aggressive tumors remains dismal with a 5-year survival between 0 and 30%.

Identification of RPL5 and RPL10 as novel diagnostic biomarkers of Atypical teratoid/rhabdoid tumors

Background

Rhabdoid tumors (RTs) are aggressive tumors that occur most frequently in children under 2 years old, which often invade kidney (KRTs) and Center Nervous System, named Atypical teratoid/rhabdoid tumors (AT/RTs). RTs often progress fast and lead to a high lethality. RTs have a low incidence, we can hardly accumulate enough samples to elicit the diagnosis. More importantly, histologically, RTs present a host of neural, epithelial, mesenchymal, or ependymal patterns, which makes them rather variable and difficult to diagnose. Molecularly, RTs are diagnosed mainly on the lack of SMARCB1/INI1 protein expression, which, on the one hand, accounts for 75% of RTs, on the other hand, loss of expression of SMARCB1 is not exclusive to RTs. So, there is a need to find more accurate diagnose markers of RTs.

Methods

In this study, we analyzed 109 samples including AT/RT, KRT and corresponding normal samples downloaded form NCBI GEO database. First, we identified the differentially expressed lncRNAs and PCGs in AT/RT, KRT and corresponding normal samples. Second, we evaluated the co-expression relationship between lncRNA and PCG, and defined four types of the dysregulated PCG-lncRNA pairs. Third, we compared the differentially expressed genes, the dysregulated PCG-lncRNA pairs and commonly known cancer genes, we get potential diagnostic markers. Then, the potential diagnostic markers were subjected to Receiver operating characteristic (ROC) analysis to assess the diagnostic accuracy. Importantly, differential expression of the marker genes in different tumors was shown to distinguish AT/RT and KRT from other pediatric tumors specifically.

Results

We compared the expression profiles between 47 AT/RTs, 31 KRTs, 8 normal brain samples, and 23 normal kidney samples. After applying a stringent set of criteria on the gene expression profiles, we identified 3667 PCGs and 81 lncRNAs differentially expressed in AT/RT, 3809 PCGs and 34 lncRNAs differentially expressed in KRT tissues. Next, we compared the three sets(AT/RT versus control brain samples, KRT versus control kidney samples, and AT/RT versus KRT) of differentially expressed lncRNAs and PCGs, 491 PCGs and 2 lncRNAs appeared in all three sets. We examined the correlation of the expression levels of these genes in the ‘three-set overlap’ group and identified four types of dysregulated lncRNAs and PCGs. By compared these genes to the well-known cancer driver genes, 19 PCGs were selected as potential candidates of diagnostic markers. Filtered with the number of the corresponding co-expressed lncRNA (namely “degree”), eight PCGs with more than five lncRNAs in the ‘three-set overlap’ group were selected as candidate diagnostic markers. Among them, RPL5 and RPL10 exhibited high sensitivity and specificity in diagnosis of AT/RT and KRT. However, when these two genes were used to distinguish AT/RT and KRT from other pediatric tumors, only AT/RT can be distinguished from medulloblastoma.

Conclusions

Our study mined existing GEO datasets for novel diagnostic markers associated with Rhabdoid tumors, and identified RPL5 and RPL10 as potential diagnostic markers for AT/RT. These two biomarkers may be used as supplementary biomarkers to canonical diagnostic tools such as biopsy and immunohistochemistry.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0681-1) contains supplementary material, which is available to authorized users.

Multimodal treatments combined with gamma knife surgery for primary atypical teratoid/rhabdoid tumor of the central nervous system: a single-institute experience of 18 patients

OBJECTIVES

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare, highly malignant tumor of the central nervous system with poor prognosis. Nowadays, multimodal management, including surgery, chemotherapy (CMT), and radiation therapy (RT), is advocated. However, AT/RT treatment with gamma knife surgery (GKS) was rarely reported. The aim of this study was to assess the efficacy and safety of GKS for the treatment of AT/RT.

PATIENTS AND METHODS

Medical records of AT/RT patients who underwent surgery from 2007 to 2014 at the West China Hospital were retrospectively reviewed and statistically analyzed.

RESULTS

Eighteen patients (12 males and 6 females) were presented with AT/RTs. Median age during presentation was 20.5 months (range, 4-179 months). Twelve patients were < 3 years and six patients were > 3 years. Tumor location was supratentorial in seven patients, infratentorial in ten patients, and center area of the brain in one patient. Treatments performed were as follows: surgery alone in two patients, surgery+RT in two patients, surgery+CMT in five patients, surgery+CMT+RT in two patients, and surgery+CMT+RT+GKS in seven patients. The 2-year overall survival (OS) rate and event-free survival (EFS) rate for all 18 consecutive patients were 33.3 and 27.8%, respectively. Cox regression analyses showed that multimodal management combined with GKS was an independent positive prognostic factor for OS.

CONCLUSIONS

Although AT/RTs are lethal cancer types, the OS of the disease was improved by using multimodal therapeutic strategies, including surgery, CMT, and RT, combined with GKS.