Atypical teratoid/rhabdoid tumor (AT/RT)

Abstract

Atypical Teratoid/Rhabdoid Tumor (AT/RT) is a rare and aggressive tumor of the Pediatric Central Nervous System (CNS) that was first described in 1987 (Biggs et al. 1987). Its aggressive behavior and predilection for infants who are less than 2 years of age enticed further study and pathological characterization over the 1990s (Burger et al. 1998; Rorke et al. 1996b). AT/RT histopathology is characterized by complex rhabdoid, epithelial, and mesenchymal cellular morphology and is genetically defined by loss of SMARCB1. Despite this early observation, AT/RT remains a challenging disease, with high mortality rates despite aggressive multimodality therapy including surgery, various chemotherapy regimens with or without stem cell transplant, intrathecal chemotherapy, and radiotherapy. The challenge is due in part to the very young age of presentation for most patients which can limit aggressive treatment particularly radiotherapy, as well as the relatively high rate of disseminated disease at diagnosis. Retrospective series, reported across multiple institutions, helped guide the development of a Children Oncology Group (COG) study designed for AT/RT (ACNS0333) that closed for accrual in February 2014. This was the first cooperative group prospective study dedicated for ATRT patients in an attempt to standardize the approach to treat AT/RT based on best available data from previous published experiences This chapter discusses the epidemiology of AT/RT, clinical features and evaluation, pathology and genetic abnormalities, and current treatment approaches. In addition, experimental therapies under investigation, as well as salvage treatment options, are reviewed.