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Soft tissue sarcoma is a type of cancer that grows in the body’s soft connective tissue including muscle, nerves, tendons, fat, and walls of blood and lymph vessels. Soft tissue sarcomas can be divided into two main types:
Soft tissue sarcomas account for about 7% of all childhood cancers. Rhabdomyosarcoma is more common in younger children, and NRSTS is more common in adolescents. The clinical behavior of soft tissue sarcomas can range from locally aggressive to highly metastatic.
Soft tissue sarcomas are named for the tissue which they most resemble:
Certain inherited conditions can increase risk for soft tissue sarcomas. Children who have been exposed to ionizing radiation are also at higher risk. Treatment for soft tissue sarcoma usually includes surgery, chemotherapy, and/or radiation therapy.
Drummond CJ, Hanna JA, Garcia MR, Devine DJ, Heyrana AJ, Finkelstein D, Rehg JE, Hatley ME. Hedgehog Pathway Drives Fusion-Negative Rhabdomyosarcoma Initiated From Non-myogenic Endothelial Progenitors. Cancer Cell. 2018 Jan 8;33(1):108-124.e5. https://www.cell.com/cancer-cell/abstract/S1535-6108(17)30524-X. doi: 10.1016/j.ccell.2017.12.001.
Rhabdomyosarcoma is a type of soft tissue tumor that often develops in muscle. However, it can form anywhere in the body and is the most common pediatric soft tissue sarcoma. It usually affects children under 10 years of age and can develop before birth.
There are two types of rhabdomyosarcoma:
Certain factors may increase risk for rhabdomyosarcoma including age, gender, and ethnicity.
Symptoms of rhabdomyosarcoma depend on where the tumor is located. Signs and symptoms of rhabdomyosarcoma include:
Several types of procedures and tests are used to diagnose rhabdomyosarcoma. These include:
Depending on the location of the tumor, additional tests may be needed including:
Site-specific evaluations may be needed depending on tumor location. A multidisciplinary medical team is important to provide optimal care throughout treatment.
In rhabdomyosarcoma, there are different ways the disease can be classified. This can help doctors better understand the disease and plan appropriate treatments.
Rhabdomyosarcoma is grouped based on tumor location, spread of disease, and result of surgery.
|Group||Spread of disease|
No disease after surgery
|The tumor is limited to one area and is completely removed with surgery.|
Microscopic disease after surgery
|The tumor is limited to one area and is removed with surgery, but cancer cells are found in nearby tissue that surrounded the tumor (margin) and/or lymph nodes.|
Significant disease after surgery
|The tumor is limited to one area but cannot be completely removed with surgery.|
|The tumor has spread to other parts of the body at diagnosis (metastatic).|
Rhabdomyosarcoma can also be staged using the TNM system. This system considers 3 factors:
Using the TNM System, rhabdomyosarcoma can be divided into 4 stages.
|Stage||Location||Tumor Size||Lymph Nodes||Metastasis|
|Where is the primary tumor?||How large is the tumor?
||Are cancer cells found in nearby lymph nodes?||Has the cancer spread to other parts of the body?|
|1||Favorable: Tumor is in the area of the eye, head or neck or in the genitorurinary tract
Exceptions: Tumor is located near the brain or spinal cord or in the bladder or prostate
||Yes or No||No|
|2||Unfavorable: All other sites
||Less than 5 cm
|3||Unfavorable: All other sites
Less than 5 cm
Greater than 5 cm
Yes or No
||Any size||Yes or No||Yes|
The chance of recovery from rhabdomyosarcoma depends on several factors:
Doctors classify rhabdomyosarcoma patients into risk groups to help plan treatments. Groups are based on the stage of disease and the ability of surgery to remove the tumor.
This information helps doctors decide what treatments to use, dose of medication, and the number of treatments needed.
If rhabdomyosarcoma has recurred, prognosis may be influenced by where in the body the cancer came back, how much time passed between the original cancer and recurrence, and what therapies were originally used to treat the cancer.
Children with localized rhabdomyosarcoma have greater than 70% chance of long term cure. About 20% of patients have metastatic disease at diagnosis. If the cancer has already spread at diagnosis (metastatic rhabdomyosarcoma), the chance of survival is less than 30%.
Approximately 30% of patients with rhabdomyosarcoma will have recurrence of cancer. Rhabdomyosarcoma may recur at the location of the initial tumor or in other sites. Recurrent rhabdomyosarcoma is difficult to treat, and the chance of cure is low.
Rhabdomyosarcoma requires a combination of treatments including chemotherapy, surgery, and/or radiation therapy. All children receive systemic chemotherapy as part of treatment for rhabdomyosarcoma. This is important to treat microscopic spread of disease that may not be detected. Tumors visible on imaging are also treated with surgery and/or radiation therapy.
The chemotherapy regimen for rhabdomyosarcoma includes vincristine, actinomycin D, and cyclophosphamide and irinotecan. A standard course of treatment is 14-16 cycles (period of treatment followed by period of rest).
Many children are offered treatment for rhabdomyosarcoma as part of a clinical trial.
Targeted therapies are newer drugs that act on specific targets of cancer cells to stop them from growing. Kinase inhibitors and monoclonal antibodies are being studied in the treatment of rhabdomysarcoma. Kinase inhibitors act to block a protein that signals cancer cells to grow. Monoclonal antibody therapy uses special proteins that attach to cancer cells to kill the cells or slow cell growth.
Non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) are a group of tumors that develop in soft tissues of the body. Although there are many types of NRSTS, they are usually treated in a similar way.
NRSTS account for about 4% of all childhood cancers. They are most common in adolescents. There are about 500-600 patients diagnosed with NRSTS in the United States each year.
NRSTS can form anywhere in the body but are most often found in the arms and legs. NRSTS can also occur in the head and neck, chest, abdomen, and pelvis.
The most common types of NRSTS in children include:
Other types of NRSTS are clear cell sarcoma, epithelioid sarcoma, hemangiopericytoma, leiomyosarcoma, liposarcoma, malignant fibrous histiocytoma, non-synovial cell sarcoma and undifferentiated sarcoma.
NRSTS in children are most often seen in two age groups: infants and adolescents. They occur slightly more often in males. Previous treatment with radiation therapy can also increase risk for NRSTS.
Certain inherited conditions can increase risk for rhabdomyosarcoma. These include Li-Fraumeni syndrome (P53 mutations), Neurofibromatosis type 1 (NF1), familial adenomatous polyposis (FAP), Werner syndrome, Retinoblastoma 1 (RB1) gene changes, and SMARCB1 (INI1) gene changes.
Symptoms of NRSTS depend on where the tumor is located. Often there are no symptoms in the early stages other than a painless lump. Problems such as pain or weakness may develop as the tumor grows and presses on other structures. More advanced disease can sometimes produce symptoms such as fever, sweating, or weight loss.
Several types of procedures and tests are used to diagnose rhabdomyosarcoma. These include:
Soft tissue sarcomas are classified by stage. Staging is based on features of the tumor such as size, whether it has spread, and grade of the tumor.
Grade refers to the way cancer cells look under the microscope. The grade helps predict how likely the cancer is to spread. Higher grade tumors tend to grow and spread faster compared to lower grade tumors.
For soft tissue sarcoma, tumor grade is based on 3 factors: differentiation, mitotic count, and necrosis.
Each factor is given a score. The higher the total score, the higher the tumor grade.
Soft tissue sarcomas can be grouped into four stages. The American Joint Committee on Cancer (AJCC) uses the following criteria:
|Stage IA||The tumor is no larger than 5 centimeters across. It has not spread to lymph nodes or other parts of the body.||1|
The tumor is larger than 5 centimeters across. It has not spread to lymph nodes or other parts of the body.
The tumor is no larger than 5 centimeters across. It has not spread to lymph nodes or other parts of the body.
|2 or 3|
The tumor is 5-10 centimeters across. It has not spread to lymph nodes or other parts of the body.
|2 or 3|
The tumor is greater than 10 centimeters across. It has not spread to lymph nodes or other parts of the body.
|2 or 3|
The tumor is any size and any grade. It has spread to nearby lymph nodes and/or other parts of the body.
The prognosis, or chance of recovery, from NRSTS depends on several factors:
Patients with a favorable tumor that meets certain conditions have a better prognosis:
|Tumor grade (histology)
||Low grade||High grade|
||Less than 5 cm||Greater then 5 cm|
|Spread of disease (metastatic)
|Complete removal with surgery
About 15% of patients have metastatic disease at diagnosis. The lung is the most common site for metastasis of NRSTS. Rarely, NRSTS may spread to bone or lymph nodes.
If the cancer has already spread at diagnosis (metastatic disease), the chance of long-term survival is less than 20%.
Recurrent NRSTS is difficult to treat, and the chance of cure is low.
Surgery is used to remove as much of the cancer as possible. A small amount of tissue around the tumor and nearby lymph nodes are also removed to make sure that no cancer is left behind. Low risk patients may be treated with surgery alone if the tumor can be fully removed with no remaining cancer cells.
Radiation therapy may be used to treat NRSTS that cannot be removed completely with surgery. In some cases, radiation may be used before surgery to make the tumor easier to remove.
Chemotherapy (“chemo”) uses powerful medicines to kill cancer cells or stop them from growing and making new cancer cells. Chemotherapy is not as effective for NRSTS. It is most often used to treat high risk patients including those with metastatic disease or patients who cannot be treated with surgery.
Targeted therapies are being studied in the treatment of NRSTS. These drugs act on specific targets of cancer cells to stop them from growing. Certain therapies are specific for subtypes of NRSTS. Many of these treatments are being studied in clinical trials.
|Alveloar soft part sarcoma
|Perivascular epitheloid cell tumors (PEComa)
|Inflammatory myofibroblastic tumor
"Two years off therapy, we are cancer free but still not at the 5-year mark. As time passes, I find that my worries change. The stress of cancer is still there. 'Scanxiety' hits as our 6-month checkup time gets closer. But what I look for now are more post-therapy effects, especially related to proton beam radiation because it just hasn’t been around long enough to know what to expect."
– Michelle, mom to Reid
Soft tissue sarcomas can recur years into survivorship. The tumor can come back in the same place (local recurrence) or in another part of the body (distant recurrence).
Patients will receive follow-up care to screen for recurrence after treatment ends. The medical team will make specific recommendations for the types of tests needed and how often patients should be seen for checkups.
Children treated for soft tissue sarcoma are at risk for late effects related to therapy. Specific problems depend on the location of the tumor and the type of therapy received.
Long-term effects of surgery can include loss of function and changes in appearance.
Survivors treated with radiation therapy may have impaired growth, bone disease, and other problems due to treatment as well as increased risk of second cancers.
Survivors treated with systemic chemotherapy should be monitored for medication-specific late-effects which may include heart problems, kidney damage, infertility, endocrine dysfunction, and risk of second cancers.
All survivors should continue to have regular physical checkups and screenings by a primary physician. For general health and disease prevention, survivors should adopt healthy lifestyle and eating habits.
Reviewed: June 2018
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