Radiation Oncology/Peds/ATRT

[edit] Epidemiology

Estimated 2-3% of primary CNS tumors in <18 population.
Majority of patients present at age <3 yrs.
A workshop on ATRT (PMID 12142780) reported that pathologic review of a recent CCG study suggests ATRT may represent a significant proportion of brain tumors in children <3 yrs old.

Major diagnostic dilemma is distinguishing from medulloblastoma.
IHC necessary for diagnosis (vimentin, EPA, and SMA found in rhabdoid tumors but not medulloblastoma)
IN11 gene mutated in ~85% of ATRT.

Treatment strategy includes maximum surgical debulking, chemotherapy and radiation therapy.

Neurological Institute, Taipei, 2006 (1990-2003) - PMID 16406394 -- "Impact of radiotherapy for pediatric CNS atypical teratoid/rhabdoid tumor (single institute experience)." Chen YW et al. Int J Radiat Oncol Biol Phys. 2006 Mar 15;64(4):1038-43.
- 17 pts w/ ATRT who received radiotherapy as part of their treatment regimen.
- Time interval b/w surgery and RT initiation was important prognostic factor on multi-variate analysis for overall survival.

St. Jude's, 2005 (1984-2003) - PMID 15735125 -- "Atypical teratoid/rhabdoid tumors (ATRT): improved survival in children 3 years of age and older with radiation therapy and high-dose alkylator-based chemotherapy." J Clin Oncol. 2005 Mar 1;23(7):1491-9.
- 37 pts w/ ATRT (22 pts 3 yrs or younger)
- Majority of pts >3 yrs received CSI.
- 2yr OS was significantly better for pts >3 yrs old.
- The only survivors who were <3 y/o received RT as part of their tx.

Boston Regimen - PMID 15803379 -- "Continuous remission of newly diagnosed and relapsed central nervous system atypical teratoid/rhabdoid tumor."
- Early pilot data

Brown; 2007 - PMID 16855864 — "Atypical teratoid/rhabdoid tumor: the controversy behind radiation therapy." (Squire SE, J Neurooncol. 2007 Jan;81(1):97-111.)