The standard work-up for AT/RT includes:

The initial diagnosis of a tumor is made with a radiographic study (MRI or CT-). If CT was performed first, a MRI is usually performed as the images are often more detailed and may reveal previously undetected metastatic tumors in other locations of the brain. In addition, an MRI of the spine is usually performed. The AT/RT tumor often spreads to the spine. It is difficult to diagnosis AT/RT only from radiographic study; usually a pathologist must perform a cytological or genetic analysis.

Examination of the cerebrospinal fluid is important as one-third of patients will have intracranial dissemination with involvement of the cerebrospinal fluid (CSF). Large tumor cells, eccentricity of the nuclei and prominent nucleoli are consistent findings.^[18] Usually only a minority of AT/RT biopsies have Rhabdoid cells, making diagnosis more difficult. Increasingly it is recommended that a genetic analysis be performed on the brain tumor, especially to find if a deletion in the INI1/hSNF5 gene is involved (appears to account for over 80% of the cases). The correct diagnosis of the tumor is critical to any protocol. Studies have shown that 8% to over 50% of AT/RT tumors are diagnosed incorrectly.

Treatment:

Surgical option:

Surgery plays a critical role in obtaining tissue to make an accurate diagnosis. Surgery alone is not curative. In addition, 30% of the AT/RTs are located supratentorially and there is a predilection for the cerebello-pontine angle which makes surgical resection difficult. One-third or more children will have disseminated disease at the time of diagnosis. Total or near-total resections are often not possible.

Chemotherapy options:

Approximately 50% of the AT/RTs will transiently respond, but Chemotherapy by itself is rarely curative. There is no standard treatment for AT/RT. Various chemotherapeutic agents have been used against AT/RTs which are also used against other CNS tumors including cisplatinum, carboplatinum, cyclophosphamide, vincristine and etoposide.

Radiation options:

The traditional practice for childhood brain tumors has been to use chemotherapy and to defer radiation therapy until a child is older than three years. This strategy is based upon observations that children under three have significant long term complications as a result of brain irradiation. However, the long term outcomes of AT/RT are so poor that some protocols call for upfront radiation therapy, often in spite of young age.

The dose and volume of radiation had not been standardized, however, radiation does appear to improve survival. The use of radiation has been limited in children younger than three because of the risk of severe neurocognitive deficits. There are protocols using conformal, local radiation in the young child to try to cure this tumor.

External beam (conformal) radiation uses several fields that beam intersects at the tumor location; the normal brain tissue receives less radiation and hopefully is at less impact on cognitive function.

Proton beam radiation was only offered at Massachusetts General Hospital in Boston and at Loma Linda, California as of 2002. Since 2003 three or four more proton therapy centers have opened in the United States.

Chromatin re-modeling agents

This protocol is still in pre-clinical evaluation. HDAC inhibitors are a new class of anticancer agents targeted directly at chromatin remodeling. These agents have been used in acute promyelocytic leukemia and have been found to affect the HDAC-mediated transcriptional repression. There is too little understanding of the INI1 deficiency to predict whether HDAC inhibitors will be effective against AT/RTs. There are some laboratory results that indicate it is effective against certain AT/RT cell lines.

History

Atypical teratoid/rhabdoid tumor was first described as a distinct entity in 1987. Before 1978, when rhabdoid tumor was described, AT/RT likely was misdiagnosed as medulloblastoma. In some early reports the tumor was known also as malignant rhabdoid tumor (MRT) of the CNS. Between 1978 and 1987, AT/RT was usually misdiagnosed as rhabdoid tumor. However, both AT/RT and non-CNS MRT have a worse prognosis than medulloblastoma and are resistant to the standard treatment protocols for medulloblastoma.

By 1995, AT/RT had become regarded as a newly-defined aggressive, biologically unique class of primarily brain and spinal tumors, usually affecting infants and young children. In January 2001, the U.S. National Cancer Institute and Office of Rare Diseases hosted a Workshop on Childhood Atypical Teratoid/Rhabdoid Tumors of the Central Nervous System. Twenty-two participants from 14 institutions came together to discuss the biology, treatments and new strategies for these tumors. The consensus paper on the biology of the tumor was published in Clinical Research. The workshop's recognition that CNS atypical teratoid/rhabdoid tumors (AT/RT) have deletions of the INI1 gene indicates that rhabdoid tumors of the kidney and brain are identical or closely related entities. This observation is not surprising because rhabdoid tumors at both locations possess similar histologic, clinical, and demographic features.

ALL INFORMATION WAS USED FROM WIKIPEDIA, THE FREE ONLINE ENCYCLOPEDIA.  CLINICAL RESEARCH IS STILL UNDERWAY AND MORE RECENT UPDATES MAY NOT HAVE BEEN POSTED.  FOR MORE INFORMATION VISIT en.wikipedia.org/wiki/ATRT OR Atypical Teratoid / Rhabdoid Tumor (ATRT) AT ST. JUDE'S WEBSITE.