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Atypical Teratoid / Rhabdoid Tumor (AT/RT)

What is AT/RT?

Atypical teratoid/rhabdoid tumor (AT/RT) is a fast-growing tumor that occurs in the brain and spinal cord. AT/RT is very rare. It accounts for about 1-2% of central nervous system (CNS) tumors in children. There are about 75 new cases of AT/RT each year in the United States. AT/RT most often occurs in young children under 3 years of age. It is the most common malignant CNS tumor in infants under 1 year of age.

What is AT/RT? AT/RT is a tumor that most often develops in the cerebellum and the brain stem.

AT/RT is a tumor that most often develops in the cerebellum and the brain stem.

AT/RTs can occur in different places throughout the brain and spinal cord. In children, about half of AT/RTs develop in the cerebellum or brain stem. They can also spread through the cerebrospinal fluid (CSF) to other parts of the brain and spinal cord.

AT/RT is an aggressive cancer. Treatment usually involves a combination of therapies which may include surgery, chemotherapy, and radiation therapy. Even with current treatments, AT/RT is very hard to cure.

Risk Factors and Causes of AT/RT

Most AT/RTs occur in children ages 3 and younger. However, these tumors may also occur in older children and adults. AT/RTs are closely related to tumors that occur in other places in the body such as the kidney (rhabdoid tumor of the kidney). They are slightly more common in males than females.

AT/RT is a type of embryonal tumor. These tumors are thought to begin in fetal cells in the brain of a developing baby (embryo). Embryonal tumors are most common in young children and are very rare in adults. About half of embryonal tumors in infants under 1 year of age are AT/RTs.

Certain changes in genes and chromosomes within the tumor cell are associated with AT/RT. Usually, it is not known why these changes occur. In some cases, the gene changes may be passed from a parent to a child.

Gene Changes in AT/RT

Malignant rhabdoid tumors, including AT/RT, have a common abnormal gene. More than 95% of AT/RTs are related to a change in the SMARCB1 gene (also known as INI1, SNF5, and BAF47 gene). About 1-2% of the time malignant rhabdoid tumor is caused by a mutation in the SMARCA4 gene.

The SMARCB1 and SMARCA4 genes are tumor suppressor genes. A tumor suppressor gene tells the cell to make a protein to stop the growth of tumor cells. When the gene does not work, the protein is not made, and tumor cells can keep growing.

In most cases, the gene mutation occurs only in the cells of the tumor. However, about 30% of children with AT/RT have rhabdoid tumor predisposition syndrome (RTPS). Patients with the syndrome have a germline mutation with the gene change in every cell in their body. This mutation can be inherited from a parent or can be a new mutation that happens by chance.

Genetic testing and counseling is important for family members and patients with rhabdoid tumor. RTPS can increase the risk of several different cancers and benign tumors called schwannomas. Children with AT/RT and rhabdoid tumor predisposition syndrome have a higher risk of developing second tumors. Gene changes in rhabdoid tumor predisposition syndrome can be passed on to children.

Learn more about rhabdoid tumor predisposition syndrome:

Symptoms of AT/RT

Signs and symptoms of AT/RT can vary based on the child’s age and tumor location. These tumors grow quickly, and symptoms may worsen in a very short time. AT/RT symptoms may include:

  • Headache, which is often worse in the morning or improves after vomiting
  • Nausea and vomiting
  • Decreases in activity level or alertness
  • Fatigue or sleepiness
  • Loss of balance or problems walking
  • Unusual eye or face movements
  • Changes in personality or behavior, irritability
  • Increased head size in infants
  • Increased fullness of the fontanel ("soft spot" at the top of the skull)
Atypical Teratoid/Rhabdoid Tumor (AT/RT) is an aggressive and fast-growing tumor. Using magnetic resonance imaging (MRI), doctors can see the size and location of the tumor.

Atypical Teratoid/Rhabdoid Tumor (AT/RT) is an aggressive and fast-growing tumor. Using magnetic resonance imaging (MRI), doctors can see the size and location of the tumor.

Diagnosis of AT/RT

Tests to diagnose AT/RT include:

  • A physical exam and medical history helps doctors learn about symptoms, general health, past illness, and risk factors.
  • Genetic testing and counseling is recommend for patients with AT/RT. Patients are tested for the SMARCB1 (INI1) and SMARCA4 genes.
  • A neurological exam examines the function of the brain, spinal cord, and nerves. These tests measure different aspects of functioning including memory, vision, hearing, muscle strength, balance, coordination, and reflexes.
  • Imaging tests such as magnetic resonance imaging (MRI) create detailed pictures of the brain and spinal cord. AT/RTs can look similar to other tumors on imaging, so other tests are needed for a diagnosis. An ultrasound of the kidney may be used to check for rhabdoid tumor of the kidney.
  • A lumbar puncture may be performed to look for cancer cells in the cerebrospinal fluid.
  • A biopsy is used to diagnose AT/RT. In a biopsy, a small sample of the tumor is removed during surgery. A pathologist looks at the tissue sample under a microscope to identify the specific type of tumor. The cells of AT/RT look different from healthy cells. Cellular markers in the tissue are used to examine specific proteins in the cells. A specific antibody stain is used to check for the SMARCB1 or SMARCA4 protein in the cancer cells. AT/RT cells lack this protein, which confirms the diagnosis of the tumor.
An ultrasound may be used to look for rhabdoid tumor of the kidney.

An ultrasound may be used to look for rhabdoid tumor of the kidney.

Grading and Staging of AT/RT

There is no standard staging system for AT/RT. Tumors are classified as newly diagnosed or recurrent.

AT/RT is a high-grade (grade IV) tumor. It is an aggressive cancer. Approximately 15-30% of patients have spread of disease to the cerebrospinal fluid (CSF) or meninges at diagnosis. This spread of disease to the meninges is called leptomeningeal metastases.

Prognosis for Children with AT/RT

AT/RTs are fast-growing and difficult to treat. The long-term outlook for children with AT/RT is usually poor, but advances in therapy have helped some children.

Factors that influence prognosis include:

  • Age of the child. Children under 3 years old have a worse prognosis.
  • Whether the cancer has spread to other areas of the brain and spinal cord or to the kidney at the time of diagnosis. AT/RT that has spread is hard to treat.

The 5-year survival rate for children with AT/RT is approximately 50%. However, this varies widely depending upon the age at diagnosis and spread of disease. Children less than 3 years of age with metastatic disease have the worst prognosis with less than 10% chance of long-term cure.

Treatment of AT/RT

Treatment depends on several factors including the size and location of the tumor, the child’s age, and the spread of disease. AT/RT is a very aggressive cancer, and most patients receive multiple types of treatments. AT/RT treatment may include surgery, chemotherapy, and radiation. Treatment for AT/RT is often through a clinical trial.

  1. Surgery is used to both diagnose and treat AT/RT. If AT/RT is confirmed with a biopsy, the surgeon will remove as much of the tumor as possible. These tumors are often difficult to remove completely because of their location in the brain and how quickly they spread.

  2. Chemotherapy is often used along with surgery and/or radiation to treat AT/RT. Chemotherapy may systemic, regional, or intrathecal. High-dose chemotherapy with stem cell rescue is also used to treat this cancer.

  3. Radiation therapy is sometimes used in addition to other treatments. How radiation therapy is used depends on the age of the child, location of the tumor, and if it has spread.

    Radiation therapy uses beams of radiation, X-rays or protons, to shrink tumors and kill cancer cells. Radiation works by damaging the DNA inside cancer cells.

    Radiation therapy uses beams of radiation, X-rays or protons, to shrink tumors and kill cancer cells. Radiation works by damaging the DNA inside cancer cells.

  4. Targeted therapies work by acting on, or targeting, specific features of tumor cells. Children with AT/RT may be eligible for ongoing clinical trials using targeted therapy. These therapies are used at the time of diagnosis or at recurrence. Targeted therapies being studied in AT/RT include alisertib and tazemetostat.

Steroid and anti-seizure medications may be needed to help manage symptoms. Incorporating palliative care and support services such as rehabilitation, psychology and social work can help patients and families manage symptoms, promote quality of life, and make care decisions. Additional support may be needed to address issues in learning, developmental milestones, and coping with cancer.

Life after AT/RT

Ongoing follow-up care, laboratory tests, and routine imaging are needed to monitor patients for recurrence or progression of disease. The care team will set a schedule based on response to treatment and individual patient needs.

AT/RT patients and family members should receive genetic testing and counseling. Children with a germline SMARCB1 or SMARCA4 changes have rhabdoid tumor predisposition syndrome, and they are at an increased risk of developing rhabdoid tumors. Patients with rhabdoid tumor predisposition syndrome need regular medical care and periodic ultrasound exams of the kidney to watch for kidney tumors.

Children treated for AT/RT should be monitored for adverse effects of treatment. Late effects may include neurocognitive and endocrine problems due to radiation. Chemotherapy and radiation therapy also increase risk for second cancers. Families should talk to their doctors about risks related to the specific treatments children received.

Supportive Care for Children with AT/RT

Especially for younger children, the prognosis for AT/RT is poor. Balancing quality of life with cancer-directed therapy is important. Families should talk to their care team about what problems to expect and ways to help manage them. Including palliative care or quality of life services can help families manage symptoms, navigate difficult conversations, and make decisions that align family wishes with goals of care.

More: Life After Brain Tumors

Reviewed: November 2019