Rhabdomyosarcoma: Definition, Types, Symptoms, Diagnosis, Treatment and Prognosis

They are cancerous tumors that can develop in bones, soft tissues (such as muscles), or connective tissue (tendons or cartilage).

Rhabdomyosarcoma is the most common malignant soft tissue tumor in children and young adults. It is a rare tumor in adults over 30 years of age.

Males are affected slightly more than females. More than half of the cases occur under the age of 10.

Most rhabdomyosarcomas occur without predisposing to risk factors. In some cases, these tumors are associated with a genetic predisposition to cancer, such as Li-Fraumeni syndrome.

Rhabdomyosarcoma can affect regional lymph nodes at a higher rate than other soft tissue sarcomas.

The malignant cells of this tumor have characteristics of skeletal muscle development.

Although rhabdomyosarcoma can appear in the extremities, it is more commonly seen in other areas: the head and neck region, the vaginal area in women, the testicular area in men, or the bladder and prostate.

Types of rhabdomyosarcoma

Embryonic

This is the most frequent and common type in children under 10 years of age, frequently occurring in the neck, head, or genital and urinary organs.

Alveolar

This type affects children of all ages and usually occurs during adolescence, most often developing on the arms or legs, chest, abdomen, genitalia, or anal area.

Anaplastic

Although this type is rare, it is more common in adults than in children.

Symptoms

Most commonly the disease presents as a painless mass, inflammation, or lump in a muscle and continues to grow.

The symptoms of rhabdomyosarcoma are associated with where the tumor is located.

Alveolar rhabdomyosarcoma affects the muscles of the extremities and trunk, and the pain associated with these tumors can be mistaken for a deep hematoma or injury.

The tumor may be very superficial (close to the skin), so there may be a lump that does not go away after a normal period of time.

Other symptoms may include a general feeling of tiredness or nausea for no recognized reason.

It can also be diagnosed as a result of bleeding or pain at the site.

Sometimes the tumor appears as a grape-like mass, unique among soft tissue tumors.

Tumor growth can cause pain and can also affect the function of the part of the body where the tumor is located.

Diagnosis of rhabdomyosarcoma

A doctor may initially suspect a soft tissue rhabdomyosarcoma tumor when a muscle injury that is not healing is observed.

On physical examination there may be a lump that is considered abnormal. Additional diagnostic tests are needed to determine if this may be a soft tissue tumor process.

Physical exam and medical history

The oncologist (cancer doctor) will review your family’s medical history and perform a complete physical exam on your child.

Computed tomography

This test is another one that is necessary for cancer staging. It reveals whether the cancer has metastasized.

This quick and painless imaging procedure uses X-rays to create multiple cross-sectional images of bone and tissue to reveal tumors, their size, and whether they have spread to other areas.

Magnetic resonance imaging

An MRI allows doctors to better see the extent of a tumor.

It is important to know if the tumor is “invading” other tissues as treatment plans (such as surgical options) are being considered.

It is also used to determine if there has been any spread of the tumor.

Biopsy

A biopsy is necessary to determine the exact type of tumor. It is important that the biopsy be performed by a specialist experienced in appropriate limb tumor biopsies.

An improperly performed biopsy can limit surgical options and, in some cases, make amputation the only surgical option.

Treatment

Removal of the tumor is one of the most important aspects of treatment, therefore surgery is the first treatment considered for anyone diagnosed with rhabdomyosarcoma.

Sometimes the tumor is in a place where it can be surgically removed, if this is the case then chemotherapy and / or radiation may be tried with the goal of shrinking the tumor so that it can be surgically removed.

Chemotherapy, or the use of medications, is necessary for anyone diagnosed with rhabdomyosarcoma.

Ideally, chemotherapy should be started after the tumor is removed.

Chemotherapy has been shown to reduce the chance that the tumor will return to the area where it was first found or to other areas of the body.

Radiation therapy, or the use of energy like X-rays, may be necessary if the entire tumor cannot be surgically removed.

It can also be considered if the biopsy results show that the tumor is a type that is extremely aggressive.

Treatment and monitoring of localized diseases

Treatment for local disease includes a combination of chemotherapy and surgery.

Radiation may also be used when complete tumor resection has not been possible.

Chemotherapy is indicated for all patients with rhabdomyosarcoma, but the amount of chemotherapy and the duration of treatment may vary depending on risk factors.

Drugs that have been shown to be active in rhabdomyosarcoma include vincristine, actinomycin, cyclophosphamide, ifosfamide, doxorubicin, carboplatin, etoposide, irinotecan, and topotecan.

These drugs are administered in various combinations depending on the evaluation of the disease.

The two-drug regimen, vincristine and actinomycin, is used for those with a favorable prognosis, and alternative combinations of two or three drugs are used in other settings.

Treatment and monitoring of metastatic disease

Metastatic disease most often occurs in the lungs, lymph nodes, or bone marrow, but many other locations are possible.

Metastatic disease that develops after initial or locally recurrent treatment is still treatable, but the outcome is generally less favorable and, in particular, for those with metastatic disease, the overall prognosis is guarded.

The role of intensive regimens using bone marrow or peripheral blood stem cells is unproven at this time.

When rhabdomyosarcoma occurs in adults, it is generally the pleiomorphic subtype that augurs a less favorable prognosis.

Treatment can be administered similarly to regimens used in children, although actinomycin is used less frequently in the adult population.

Staging of rhabdomyosarcoma

Staging for any type of cancer involves determining whether the cancer is only in the area where it was originally found (local) or whether it has spread (metastasized).

Knowing the stages helps treating physicians determine the best treatment approach.

Staging rhabdomyosarcoma is slightly more complex than many other types of tumors because it involves three different aspects of the tumor, including evaluating the tumor after it has been surgically removed (assuming it can be removed).

First, the stage based on the size of the tumor and whether imaging tests show that the cancer has spread.

Stage I

The tumor is small and has not spread.

Stage II or III

The tumor has spread to surrounding structures.

Stage IV

The tumor has spread to other parts of the body.

Second, disease is grouped based on whether the cancer has spread and whether all the cancer was removed by surgery:

Group I

All visible tumor is removed during surgery and the margins are negative; It does not spread to other areas.

Group II

All visible tumor is removed during surgery, but the margins are positive. It does not spread to other areas.

Group III

All visible tumor could not be completely removed; The tumor has spread to the lymph but not to other organs.

Group IV

The cancer has already shown signs of spreading to other organs at the time of diagnosis.

By combining the information about stage and group, doctors can classify the child’s tumor into the risk group based on how aggressive the tumor is.

Assigning a risk group helps guide the next treatment.

Low risk

As rhabdomyosarcoma is an aggressive tumor, there is no alveolar rhabdomyosarcoma in the low-risk group.

Intermediate risk

Includes children with stage 1,2 or 3 disease.

High risk

Includes children with stage 4 disease.

Prognosis of rhabdomyosarcoma

The prognosis, or the possibility of survival, is closely related to the characteristics of the tumor: how big it is, how old the child is, where the tumor started and is it metastatic, among others, that is, all the information included in the cancer staging.

Often the information that treating physicians have is the 5-year survival rate for a type of cancer at a specific stage, based on information from studies of large numbers of people who have been diagnosed with that type of cancer.

The 5-year survival rate is established after cancer diagnosis.

General survival statistics based on risk group are:

  • The 5-year survival rate for the low-risk group is more than 90% for children in the low-risk group.
  • The 5-year survival rates for the intermediate-risk group range from about 60% to about 80% for children in this group. The rate varies depending on the location of the tumor, the stage, and the age of the child (children 1 to 9 years old tend to do better than older or younger children).
  • The five-year survival rate of the high-risk group is generally around 20% to 40% because children in this group have metastatic disease at the time of their diagnosis. Children 1 to 9 years of age tend to have a better outlook than younger or older patients.