Atypical Teratoid Rhabdoid Tumor (ATRT)

An atypical teratoid rhabdoid tumor (ATRT) is a very rare, aggressive tumor of the central nervous system, occurring mostly in the cerebellum, the part of the brain that controls movement and balance, or the brain stem, the part of the brain that controls basic body functions.

ATRTs usually occur by age 3, but sometimes are found in older children. ATRTs represent only 1 to 2 percent of childhood brain tumors. These tumors are part of a larger group of malignant tumors called rhabdoid tumors, which also can occur outside the brain. ATRTs may be localized to one part of the brain, or they can spread to other locations in the brain, spine, or body.

Successfully treating your child’s ATRT depends on where the tumor is located and whether the tumor has spread.

For many tumors, we use a system of classification called “staging” to evaluate cancers. However, there is currently no standardized classification system for atypical teratoid rhabdoid tumors. An ATRT may be:

• Localized, occurring in only one location in the brain
• Disseminated, spread to multiple locations in the brain, spinal cord, or body

Atypical teratoid rhabdoid tumors (ATRTs) can cause a variety of symptoms in children depending on their size and location. Keep in mind, the symptoms may resemble other more common conditions or medical problems. It is important to consult your child's physician if you have concerns.

ATRT symptoms can come on quickly, in a matter of days or weeks, due to the fast-growing nature of these tumors. ATRT symptoms include:

• Headache, generally upon awakening in the morning
• Hydrocephalus, where there is a buildup of fluid in the brain which can result in increased head size in infants or headaches and vomiting in older children
• Nausea and vomiting, often worse in the morning and improve throughout the day
• Lethargy and fatigue
• Trouble with balance and coordination

As a parent, you undoubtedly want to know what may have caused your child’s tumor. It’s important to remember that nothing you could have done or avoided doing would have prevented the tumor from developing. In most cases, atypical teratoid rhabdoid tumors are associated with a specific mutation (INI1) that can occur spontaneously or be inherited. More than 90 percent of cases of ATRT are associated with this mutation and are not inherited. However, the cause of this abnormality is not known. If this mutation (INI1) has been inherited, your child may be at increased risk of developing other tumors.

The first step in treating your child's atypical teratoid rhabdoid tumor (ATRT) is forming an accurate and complete diagnosis. ATRT is most commonly diagnosed from imaging studies and biopsy. Your child's doctor will likely conduct tests including:

• A physical exam and complete medical history, including a neurological function test of reflexes, muscle strength, eye and facial movement, coordination, and alertness
• Magnetic resonance imaging (MRI), a diagnostic procedure that produces detailed images of the structures within the brain and spine
• Computerized tomography scan (CT or CAT scan), a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images of the body from horizontal and vertical perspectives
• Biopsy, a tissue sample from the tumor during a surgical procedure
• Lumbar puncture (spinal tap): removal a small sample of cerebrospinal fluid (CSF) to determine if any tumor cells have spread
• Ultrasound, a diagnostic imaging procedure that does not use X-rays, but sound waves to evaluate organs in the body
• Genetic testing, to look for a specific genetic defect often associated with ATRT and to ensure your child is not at an increased risk of developing other tumors

There may be other diagnostic tests that your doctor will discuss with you depending on your child's individual situation. After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we will be able to discuss the results and outline the best possible treatment options.

Your child's physician will determine a specific course of ATRT treatment based on several factors, including your child's age; overall health and medical history; the type, location, and size of the tumor; and the extent of the disease.

ATRT treatments include:

• Neurosurgery: Surgery is usually performed first in order to remove as much of the tumor as possible.
• Radiation: High-energy waves from a specialized machine damage or shrink tumors. Precisely targeted and dosed radiation therapy is used to kill cancer cells left behind after surgery. Because ATRT occurs in children under 3, reduced intensity, limited field radiation therapy is used or radiation is avoided altogether; children over 3 generally receive radiation therapy as standard treatment.
• Chemotherapy: Chemotherapy are drugs that interfere with the cancer cells' ability to grow or reproduce. Chemotherapy can be given in several different ways, but intrathecal chemotherapy is an important part of treatment as it allows medicine to be delivered directly to the spinal fluid and the central nervous system to treat the tumor.
• Stem cell transplant: This allows children with aggressive ATRT to receive high doses of chemotherapy. This treatment aims to transfuse healthy bone marrow cells into your child after his marrow has been damaged by the intensive chemotherapy.

There is no standard treatment for recurrent ATRT. Children with recurrent disease are often referred to clinical trials for the latest experimental therapies.

Children with ATRTs are treated at Dana-Farber/Boston Children's through our Brain Tumor Center, a world leader in treating this rare disease. Our brain tumor specialists have extensive expertise in treating all types of neural tumors, including ATRTs.

At Dana-Farber/Boston Children’s, your child will:

• Receive care from neuro-oncologists, neurosurgeons, neurologists, and pediatric subspecialists
• Have access to technological advances such as the intra-operative MRI, which allows pediatric neurosurgeons to see the tumor as they operate and remove as much of it as possible
• Receive expert diagnosis by neuropathologists who use advanced molecular diagnostic testing

Because ATRT is so rare, these tumors are difficult to study. As a result, our researchers collaborate with other institutions around the country to improve our current understanding of this condition and offer new treatments to children with ATRT. Currently, researchers at Dana Farber/Boston Children’s are working with the Children’s Hospital of Philadelphia and the Broad Institute of MIT and Harvard to learn more about the molecular characteristics of atypical teratoid rhabdoid tumors.

In addition, researchers in our Brain Tumor Center are collaborating with physicians and researchers that treat other types of rhabdoid tumors in order to study the effectiveness of current treatments and to establish new, more standardized treatments for all types of rhabdoid tumors.

Through clinical trials, our researchers are testing new, targeted treatments that may help improve the survival rate for ATRT.

Most children with a diagnosis of ATRT will be treated as part of a brain tumor clinical trial. In addition to launching our own clinical trials, we also offer trials available through collaborative groups such as the Children's Oncology Group (COG) and the Pacific Pediatric Neuro-Oncology Consortium (PNOC). We are also the New England Phase I Center of the Children's Oncology Group. If your child has a progressive or recurrent tumor, they may be eligible for a number of experimental therapies available through these groups or from one of our independent clinical investigators.