Rhabdomyosarcoma

What is rhabdomyosarcoma?

Rhabdomyosarcoma is a rare cancer that starts in soft tissue. It develops from immature cells that would normally grow into skeletal muscle, the type of muscle that moves the body. Because these early muscle-forming cells exist throughout the body before birth, rhabdomyosarcoma can appear almost anywhere, including places that do not contain much muscle, such as the head and neck, the bladder, the reproductive organs, the arms and legs, and the chest or abdomen.

Rhabdomyosarcoma is a type of sarcoma, which is the general name for cancers of connective tissue such as muscle, fat, blood vessels, and fibrous tissue. It is the most common soft tissue sarcoma diagnosed in children and adolescents. Rhabdomyosarcoma in children most often appears before the age of ten, although it can also occur in teenagers and, less commonly, in adults.

Doctors group rhabdomyosarcoma into several subtypes based on how the cells look under a microscope and on their genetic features:

• Embryonal rhabdomyosarcoma is the most common subtype. It tends to affect younger children and often develops in the head and neck region or in the urinary and reproductive organs.
• Alveolar rhabdomyosarcoma is more often seen in older children and teenagers. It frequently appears in the trunk, arms, or legs and tends to behave more aggressively.
• Pleomorphic rhabdomyosarcoma occurs mainly in adults and is uncommon in children.
• Spindle cell and sclerosing rhabdomyosarcoma are less common subtypes that can occur at any age.

Because this cancer is rare and complex, it is usually managed by a team of specialists in pediatric oncology (the care of children with cancer), surgery, radiation oncology, pathology, and rehabilitation. In hospital groups such as Acibadem, this care is coordinated through the Pediatrics department together with cancer specialists.

Symptoms of rhabdomyosarcoma

Rhabdomyosarcoma symptoms depend almost entirely on where the tumor is growing and how large it has become. Many children have no symptoms at all until a lump is noticed or until the tumor presses on a nearby structure. Some of the more common signs include:

• A lump or swelling that keeps growing, which may or may not be painful
• Bulging or swelling of one eye, or a drooping eyelid
• A persistent blocked nose, nosebleeds, or nasal discharge on one side
• Headache, earache, or fluid draining from the ear
• Difficulty passing urine, blood in the urine, or trouble with bowel movements
• A mass in the vagina, or a swollen scrotum or testicle
• Abdominal pain, a swollen abdomen, or vomiting
• Bone pain, unexplained tiredness, or weight loss when the cancer has spread

The pattern of rhabdomyosarcoma symptoms varies by location. Tumors around the eye (called orbital tumors) may cause the eye to bulge forward or may lead to vision changes. Tumors near the nose, sinuses, or ear may be mistaken for a long-lasting infection. Tumors in the bladder or prostate can make it hard to urinate, while tumors in the arms or legs usually appear as a firm lump under the skin that slowly enlarges.

In early-stage disease, the only sign may be a painless lump. When the cancer has spread to other parts of the body, which doctors call metastatic disease, children may develop more general symptoms such as fever, fatigue, loss of appetite, bone pain, or easy bruising if the bone marrow is involved. None of these symptoms is specific to rhabdomyosarcoma, and most children with a lump or swelling do not have cancer. However, any lump that keeps growing should be examined by a doctor.

Causes and risk factors

In most cases, doctors cannot identify a specific cause of rhabdomyosarcoma. The cancer begins when developing muscle cells acquire changes in their DNA (the genetic instructions inside each cell) that make them multiply uncontrollably and fail to mature into normal muscle. In alveolar rhabdomyosarcoma, many tumors carry a specific genetic rearrangement in which two genes, called PAX3 or PAX7 and FOXO1, become fused together. These changes usually arise by chance in the tumor cells themselves and are not inherited.

A small number of children have an inherited condition that increases the likelihood of developing rhabdomyosarcoma. These include:

• Li-Fraumeni syndrome, an inherited condition caused by changes in the TP53 gene that raises the risk of several cancers
• Neurofibromatosis type 1, a genetic disorder that causes nerve tumors and skin changes
• Beckwith-Wiedemann syndrome, an overgrowth condition present from birth
• Costello syndrome and Noonan syndrome, rare genetic conditions affecting growth and development
• DICER1 syndrome, an inherited condition linked to several rare tumors

Some studies have explored whether exposures before birth, such as parental smoking or drug use, or a high birth weight, might slightly increase risk, but the evidence is not conclusive. Unlike many adult cancers, rhabdomyosarcoma is not linked to lifestyle choices the child or family could have controlled. Parents should know that nothing they did or did not do is known to cause this cancer in their child.

Diagnosis

Diagnosing rhabdomyosarcoma involves several steps. The process usually begins with a physical examination and a review of the child’s medical history. Because the symptoms overlap with many common childhood conditions, imaging tests are often ordered when a lump or unexplained swelling does not improve.

• Ultrasound uses sound waves to create a picture of the lump and is often the first test in children because it does not use radiation.
• Magnetic resonance imaging (MRI) uses magnets and radio waves to produce detailed images of soft tissue and is the preferred test for showing the exact size of the tumor and its relationship to nerves, blood vessels, and bone.
• Computed tomography (CT) uses X-rays to create cross-sectional images and is commonly used to check the lungs and abdomen for spread.
• Positron emission tomography (PET) scan uses a small amount of radioactive sugar to highlight areas of active cancer anywhere in the body.
• Bone scan may be used to look for spread to the bones.

Imaging alone cannot confirm the diagnosis. A biopsy, in which a small sample of the tumor is removed and examined under a microscope by a pathologist (a doctor who studies tissue), is required. The pathologist uses special stains known as immunohistochemistry to detect muscle-related proteins such as desmin, myogenin, and MyoD1, which help confirm that the tumor is a rhabdomyosarcoma. Molecular tests are then performed to look for the PAX-FOXO1 gene fusion, because tumors with and without this fusion tend to behave differently and may be treated differently.

To find out whether the cancer has spread, doctors may also perform a bone marrow aspiration and biopsy, in which a small amount of marrow is taken from the hip bone, and, for tumors near the brain or spinal cord, a lumbar puncture to check the fluid around the spine. Nearby lymph nodes may be sampled as well.

Once all results are available, the cancer is classified using a combination of stage (based on tumor size, location, and spread), clinical group (based on how much tumor remains after initial surgery), and subtype or fusion status. Together these place a child in a low, intermediate, or high risk group, which guides the intensity of rhabdomyosarcoma treatment.

Treatment options for rhabdomyosarcoma

Rhabdomyosarcoma treatment almost always combines several approaches, because this cancer can spread through the bloodstream even when the tumor appears small and localized. A team of specialists develops a plan based on the child’s risk group, the tumor location, and the child’s age and overall health. Watchful observation alone is not an appropriate approach for this cancer.

Chemotherapy

Chemotherapy, meaning medicines that kill fast-growing cells, is given to every child with rhabdomyosarcoma. It is used to shrink the main tumor and to destroy cancer cells that may have traveled elsewhere in the body but are too small to see on scans. Commonly used drugs include vincristine, actinomycin D, and cyclophosphamide or ifosfamide, often given in combinations. Treatment is usually delivered in cycles over many months, and the total length varies with the risk group. Children in the high risk group may receive additional or different drugs. Chemotherapy causes side effects such as hair loss, nausea, mouth sores, and a weakened immune system, which the care team monitors and manages closely.

Surgery

Surgery aims to remove the tumor completely while preserving as much normal function and appearance as possible. Whether and when surgery is performed depends heavily on location. Tumors in the arms, legs, or trunk can often be removed. Tumors near the eye, in the bladder, or deep in the head and neck may be difficult to remove without causing serious harm, so surgery may be limited to a biopsy, followed by chemotherapy and radiation instead. In some cases, surgery is delayed until chemotherapy has shrunk the tumor.

Radiation therapy

Radiation therapy uses high-energy beams to kill cancer cells in a targeted area. It is used for most children with rhabdomyosarcoma, especially when the tumor cannot be fully removed or when cancer cells remain at the edges of the surgical site. Modern techniques, including proton beam therapy where available, aim to limit the dose to healthy tissue. Because radiation can affect growth and development in young children, the timing and dose are planned carefully by the team.

Clinical trials

Because rhabdomyosarcoma is rare, much of what is known about the best treatment comes from cooperative clinical trials. Children may be offered enrollment in a trial, which provides access to newer approaches while contributing to knowledge that helps future patients. Participation is always voluntary.

Supportive care and rehabilitation

Supportive care runs alongside cancer treatment and includes managing pain, preventing and treating infections, maintaining nutrition, and supporting the child’s emotional wellbeing and schooling. After treatment, physical therapy and occupational therapy help children regain strength and function, particularly after surgery to a limb. Speech therapy, hearing and vision care, and dental care may be needed after treatment to the head and neck.

Living with rhabdomyosarcoma and outlook

The outlook for rhabdomyosarcoma has improved considerably over recent decades as combined treatment has become standard. Many children whose cancer is localized and belongs to the low or intermediate risk group are treated successfully and go on to live long lives. The outlook is more guarded when the cancer has spread at diagnosis, when the alveolar subtype with a PAX-FOXO1 fusion is present, in older adolescents and adults, and when the cancer returns after treatment. The rhabdomyosarcoma survival rate quoted in published sources is an average across large groups of patients and cannot predict what will happen to any individual child. Your child’s oncologist is the best person to explain what the risk group means in your situation.

Follow-up care continues for many years after treatment ends. Regular visits and scans check for any return of the cancer, most likely in the first few years. Because chemotherapy and radiation given during childhood can have late effects, survivors are monitored for issues such as changes in growth, heart or kidney function, fertility, hearing, dental development, and the small risk of a second cancer later in life. Long-term survivorship clinics can coordinate this care.

A cancer diagnosis in a child affects the whole family. Emotional support from psychologists, social workers, and parent support groups is a normal and important part of care. Siblings may also need attention and reassurance. Many families find that keeping some daily routines, staying connected with school, and asking the care team questions openly helps them cope during a long course of treatment.

Frequently asked questions

What are the first signs of rhabdomyosarcoma in children?

The first sign is usually a lump or swelling that keeps growing, or a symptom caused by the tumor pressing on something nearby, such as a bulging eye, a persistently blocked nostril, trouble urinating, or a swollen scrotum. Pain is not always present. Because these signs are shared with many harmless conditions, a doctor’s evaluation is the only way to find out the cause.

Is rhabdomyosarcoma curable?

Many children with rhabdomyosarcoma, especially those whose cancer is localized and in a lower risk group, are cured with a combination of chemotherapy, surgery, and radiation. Cure is less certain when the cancer has spread or returns after treatment. No doctor can promise an outcome, but the treating team can explain what the risk group generally means.

What is the rhabdomyosarcoma survival rate?

Survival figures depend strongly on risk group, tumor location, subtype, and the child’s age, so a single number can be misleading. In general, children with localized disease have a considerably better outlook than those with metastatic disease at diagnosis. Published statistics describe groups of patients treated in the past and do not account for individual factors or newer treatments, so they should be interpreted with the help of the oncology team.

How is rhabdomyosarcoma treated?

Rhabdomyosarcoma treatment combines chemotherapy for all patients with surgery and, in most cases, radiation therapy to control the main tumor. The exact plan is based on the risk group and tumor location and usually lasts many months. Supportive care and rehabilitation continue during and after treatment.

Can adults get rhabdomyosarcoma?

Yes, although it is much less common in adults than in children. Adults are more likely to have the pleomorphic subtype, and the disease often behaves more aggressively in adults. Treatment principles are similar, but adults may be managed by sarcoma specialists rather than pediatric oncologists.

Does rhabdomyosarcoma run in families?

Most cases occur by chance and are not inherited. A small proportion of children have an underlying genetic condition, such as Li-Fraumeni syndrome or neurofibromatosis type 1, that raises the risk. If doctors suspect an inherited condition, they may recommend genetic counseling for the family.

How long does treatment for rhabdomyosarcoma take?

Treatment commonly continues for several months to about a year, depending on the risk group and the response to therapy. Surgery and radiation are usually scheduled at specific points within the chemotherapy course. Follow-up visits then continue for many years after treatment finishes.

When to see a doctor

Most lumps and swellings in children are not cancer, but rhabdomyosarcoma is more easily treated when found early. A doctor should evaluate any of the following:

• A lump or swelling anywhere on the body that is growing, firm, or has lasted more than a couple of weeks
• One eye that bulges forward, a new drooping eyelid, or sudden vision changes
• A blocked nose, nosebleeds, or ear discharge on one side that does not clear up
• Difficulty passing urine, blood in the urine, or a mass protruding from the vagina
• A swollen or enlarged testicle or scrotum
• Persistent abdominal pain or swelling, especially with vomiting
• Unexplained bone pain, fatigue, weight loss, or fever lasting more than a few days

Children already being treated for rhabdomyosarcoma should receive urgent medical attention for a fever during chemotherapy, signs of infection, uncontrolled bleeding, severe pain, difficulty breathing, or a sudden change in alertness, because treatment can lower the body’s ability to fight infection.