Rhabdoid Tumour

Rhabdoid tumour is a rare and highly aggressive cancer that primarily affects babies and very young children, developing rapidly in the kidneys, brain, soft tissues, or other organs throughout the body.

Table of contents

• What is a rhabdoid tumour?
• Other names for this condition
• Types of rhabdoid tumours
• Who is affected by rhabdoid tumours?
• How common are rhabdoid tumours?
• Parts of the body affected
• What causes rhabdoid tumours?
• Symptoms of rhabdoid tumours
• How are rhabdoid tumours diagnosed?
• Treatment options
• Outlook and prognosis

What is a rhabdoid tumour?

A rhabdoid tumour is a very rare, fast-growing cancer that most commonly affects babies and young children. These tumours are called “rhabdoid” because when doctors examine the cancer cells under a microscope, they look similar to rhabdomyoblasts, which are cells that normally develop into muscles before a baby is born^[1].

Rhabdoid tumours are among the most aggressive childhood cancers. They grow very quickly and can spread to other parts of the body rapidly, which makes them particularly difficult to treat^[1][3]. These tumours can develop in different parts of the body, including the kidneys, soft tissues such as muscles and organs, or the brain and spinal cord^[1].

malignant rhabdoid tumor, malignant rhabdoid tumour, rdt, rhabdoid sarcoma

Other names for this condition

Healthcare professionals may use different names when referring to rhabdoid tumours. These include malignant rhabdoid tumor (MRT), rhabdoid sarcoma, or simply rhabdoid tumor. When the tumour develops in the brain or spinal cord, it is called an atypical teratoid rhabdoid tumor (ATRT)^[3].

Types of rhabdoid tumours

There are three main types of rhabdoid tumours, classified by where they develop in the body^[1]:

Rhabdoid tumour of the kidney (RTK) is a rhabdoid tumour that forms specifically in the kidney^[1].

Malignant rhabdoid tumours (MRT) are also known as extracranial or extrarenal malignant rhabdoid tumours. These tumours grow in soft tissues and organs outside the brain and kidneys. They can develop in the liver, lungs, skin, peripheral nerves, and other soft tissues throughout the body^[1][3].

Atypical teratoid rhabdoid tumours (ATRT) involve the central nervous system. These tumours start when cancerous cells form in the brain or spinal cord. Approximately 50% of these tumours develop in the cerebellum or the brainstem. The cerebellum is the part of the brain that controls movement, balance and posture. The brainstem controls breathing, heart rate, and certain nerves and muscles^[1][13].

Who is affected by rhabdoid tumours?

Rhabdoid tumours mainly affect babies and very young children. They are most common in infants between 11 months and 18 months old^[1][10]. The average age of diagnosis is 15 months^[2][4]. The condition can even occur before birth in some cases^[5].

While rhabdoid tumours primarily occur in infants and toddlers, they rarely affect older children and adults^[1].

How common are rhabdoid tumours?

Rhabdoid tumours are extremely rare. Some studies suggest that fewer than 1 person in every 1 million people will develop this type of cancer^[1][3]. In the United States, there are about 20 to 25 new cases of malignant rhabdoid tumour diagnosed each year^[2][4].

Parts of the body affected

• Kidneys
• Brain (particularly cerebellum and brainstem)
• Spinal cord
• Liver
• Lungs
• Skin
• Peripheral nerves
• Soft tissues throughout the body

What causes rhabdoid tumours?

Rhabdoid tumours are caused by changes in specific genes that help control cell growth. A genetic mutation in the SMARCB1 gene causes most rhabdoid tumours. This gene is a tumour suppressor gene, which means it normally makes a protein that helps control cell growth and prevents cells from growing too rapidly. A mutation in this gene can cause the rapid and uncontrolled growth of tumour cells^[1][10]. In about 90% of cases, a genetic change in the SMARCB1 gene is responsible for the disease^[3].

Rarely, a mutation in the SMARCA4 gene, another tumour suppressor gene, causes rhabdoid tumours^[1][5].

While some children are born with a mutated gene inherited from a parent, the majority of rhabdoid tumours occur in children with no biological family history of the condition. These cases result from a new genetic mutation that happens spontaneously^[1][10]. This means that malignant rhabdoid tumours typically do not run in families^[25].

However, there is a condition called rhabdoid tumour predisposition syndrome (RTPS) where children inherit a gene mutation that increases their risk of developing these tumours. Approximately 30 to 35 percent of children who are diagnosed with rhabdoid tumours have this syndrome^[8]. Children with this syndrome often develop tumours at a younger age and may develop multiple tumours^[5].

As part of your child’s care, they may have a genetic evaluation to determine the likelihood of passing on the mutated gene^[1][10].

Symptoms of rhabdoid tumours

The symptoms of rhabdoid tumours depend on your child’s age and where the tumour is growing in the body. Symptoms usually begin near where a tumour is developing. Because these tumours spread rapidly, signs and symptoms may develop quickly and worsen over days or weeks^[1][3][9].

In babies and very young children, the first symptoms may be difficult to recognize because infants cannot easily communicate pain or discomfort. Often, the first sign that a child has a malignant rhabdoid tumour is the discovery of a lump or mass in the child’s abdomen (belly). Because these tumours occur most frequently in infants, the child may not show any signs of pain or discomfort beyond fussiness^[2][15].

Common symptoms may include^[1][3]:

• Fever
• Headache
• Blood in the urine (hematuria)
• Nausea and vomiting
• Swollen lymph nodes
• Irritability
• Decreased appetite
• Unusual sleepiness
• Increased head size (in infants)
• Loss of balance or trouble walking
• Difficulty breathing
• Nerve paralysis
• A lump on the belly

How are rhabdoid tumours diagnosed?

Your child’s healthcare provider will perform a physical exam and ask about your child’s symptoms. They will request several tests to determine a diagnosis^[1].

Imaging tests are used to create detailed pictures of the inside of your child’s body. These may include^[1][2]:

• Ultrasound: An ultrasound uses high-energy sound waves to create images of internal organs
• CT scan (Computerized tomography scan): This creates detailed cross-sectional images of the body
• MRI (Magnetic resonance imaging): This uses magnets and radio waves to create detailed images of soft tissues
• X-rays: These may be used to look at certain areas of the body

Biopsy is essential for confirming the diagnosis. During a biopsy, doctors remove a small sample of the tumour tissue. An expert called a pathologist examines the cells from the sample under a microscope to determine what kind of tumour it is^[2][4].

If a biopsy is taken, the sample will be tested for mutations in the SMARCB1 gene (this gene also goes by the names INI1, SNF5, and BAF47). This gene is altered or turned off in nearly all rhabdoid tumours. If a mutation is found, your child’s doctor may recommend additional tests^[2][15].

In some cases, the surgeon may be able to remove the tumour during the same procedure used to obtain the biopsy^[13].

Treatment options

Because rhabdoid tumours are so rare and aggressive, there is no single standard treatment that works for all cases. Treatment usually involves a combination of different approaches, and your child’s doctor will work with you to develop a treatment plan tailored to your child’s specific situation^[2][3][15].

Prompt medical attention and aggressive therapy are important for the best possible outcome^[2][15].

Surgery

Surgery is usually the first step in treating rhabdoid tumours. The goal is to remove as much of the tumour as possible. In some cases, doctors can remove the entire tumour in one surgery. Sometimes, a second surgery may be needed to remove more of the tumour or the rest of it^[1][2][9].

Because rhabdoid tumours can be very large, complete removal may not be possible at the time of diagnosis. Even when all of the tumour is removed, additional treatment is usually given afterward^[1][9].

Chemotherapy

Chemotherapy uses powerful drugs to kill cancer cells. High-dose chemotherapy is usually given after surgery to kill any remaining cancer cells and lower the risk that the cancer will come back^[1][9][17].

Chemotherapy drugs that may be used in various combinations include cyclophosphamide, cisplatin, etoposide, vincristine, carboplatin, ifosfamide, doxorubicin, methotrexate, thiotepa, and cytarabine^[17].

Radiation therapy

Radiation therapy uses high-energy rays or particles to destroy cancer cells and shrink tumours. It is not typically used in children younger than 3 years of age because it can damage developing brain cells^[1][17].

In older children, radiation therapy may be used along with chemotherapy. There are different types of radiation therapy that may be used. Focal radiation is focused directly on the tumour, while craniospinal radiation is given to the skull and spine. One or both types may be used depending on the situation^[17].

Stem cell transplant

A stem cell transplant replaces stem cells that may have been destroyed by high-dose chemotherapy. High-dose chemotherapy followed by a stem cell transplant is often used to treat rhabdoid tumours^[1][9][17].

Before chemotherapy starts, some children will have healthy cells collected from their bone marrow. After high-dose chemotherapy is completed, these stem cells are returned to the child’s body to help rebuild their bone marrow and restore their ability to produce blood cells^[9].

Clinical trials

Children with rhabdoid tumours may be eligible to participate in a clinical trial. Clinical trials are research studies that look at new ways to prevent, find, and treat cancer. Your child’s doctor can help you understand if a clinical trial might be appropriate^[17].

Outlook and prognosis

Prognosis means a prediction of outcome. The outlook for children with rhabdoid tumours depends on many factors, including^[25]:

• Where the tumour is located in the body
• If the cancer has spread to other parts of the body
• How much of the tumour was removed during surgery
• Your child’s age at diagnosis

Unfortunately, the overall prognosis for children with rhabdoid tumours remains poor. These tumours are very aggressive and often spread quickly, making them difficult to treat^[25]. Although rhabdoid tumours often have an initial response to treatment, they very often come back quickly. Recurrence rates are high^[4][20].

Children diagnosed after the age of 2 tend to have a better prognosis than those who are diagnosed when they are younger. Children aged 3 years and older at diagnosis without disease that has spread, who are treated with aggressive surgical removal, chemotherapy, and radiation therapy, tend to have the best survival outcomes^[25].

Researchers and doctors are working to better understand these tumours and develop more effective treatments. Some children have survived longer than 18 months without their cancer returning, which provides reasons for hope^[20].

If you want information about your child’s prognosis, it is important to talk to your child’s doctor. They can provide information specific to your child’s situation^[25].