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Non-Rhabdomyosarcoma Soft Tissue Sarcoma (NRSTS)

Soft-tissue sarcomas that are not rhabdomyosarcomas are classifieds as non-rhabdyomyosarcoma soft tissue sarcomas (NRSTS). Examples of the many types of NRSTS cancers include fibrosarcoma, leiomyosarcoma, liposarcoma, neurofibrosarcoma, peripheral nerve sheath tumors and synovial sarcoma. These cancerous tumors arise in the soft tissues of the body including tendons, muscles, nerves, fatty tissue and fibrous tissue. NRSTS can essentially occur at any site in the body containing these normal types of tissues, such as in the arms and legs, the head and neck region, the chest, abdomen and pelvis. NRSTS accounts for ~ 5 percent of all pediatric cancers.

Certain types of NRSTS are most likely to affect infants (under 1 year of age), while other types are more common in adolescents and young adults. Because soft tissue is expandable, these tumors can sometimes grow rather large before they are felt or cause problems for the patient. Like all cancers, they can invade surrounding tissues and metastasize (spread) to other organs of the body.

What are the Symptoms of Non-Rhabdomyosarcoma Soft Tissue Sarcomas?

In the early stages, NRSTS usually do not cause any symptoms, especially if they are located deep inside the abdomen or pelvis where a lump cannot be felt. When the tumor grows larger a child may notice the following symptoms:

  • A swelling or lump which may or may not be painful
  • Pain or soreness caused by the tumor pressing on nerves or muscles
  • Obstruction of the bowels when tumors become large in the abdomen
  • Limping when the tumors arise in the legs

These symptoms may resemble other conditions or medical problems seen in children and young adults. Always consult a physician for a diagnosis.

State-of-the-Art Diagnostics

NRSTS are relatively rare forms of cancer, and there are many different subtypes. Because of these facts, arriving at the correct diagnosis can be particularly challenging. Multilevel, advanced diagnostics are necessary to detect, locate, identify and stage non-rhabdomyosarcoma. These tests often include direct analysis of genetic material from the tumor. This type of test requires special expertise. Once a NRSTS is diagnosed, your care team will perform imaging studies and procedures including:

  • X-ray -- often used as an initial test to identify a tumor within the chest, abdomen or in a bone
  • Magnetic resonance imaging (MRI) scan -- to determine the extent of the tumor
  • Computed tomography (CT or CAT) scan -- to identify the location of tumors within the abdomen, chest, pelvis, or other sites
  • Bone scans -- to detect rhabdomyosarcoma that may have spread to bones
  • Positron emission tomography (PET) scan - to find small tumors or check if treatment is working effectively
  • Ultrasound -- sometimes used in addition to CT or MRI to identify the location of a tumor within the abdomen or within a muscle.
  • Biopsy -- to remove a small amount of the soft tissue tumor for microscopic examination by an expert pathologist. It is very rare for NRSTS to spread to the bone marrow. However, if your doctors have a reason to suspect this, a sample of bone marrow is also collected as part of the staging procedures. Certain types of NRSTS can also frequently spread to lymph nodes that are near to the primary tumor site. In this case, biopsies may include samples of the lymph nodes in the region.
  • Lumbar puncture/spinal tap -- to remove a small amount of cerebral spinal fluid for microscopic evaluation. This test is only needed if it appears that the rhabdomyosarcoma has extended into the brain or spinal cord.

Using extensive, specialized testing of the tissue, the pathologist is able to confirm the diagnosis and identify the type of sarcoma. The sarcoma team will assign a stage to the tumor, which takes into consideration the size of the tumor and whether it has spread to other sites in the body. With detailed analysis of the pathology material to determine if the NRSTS is high- or low-grade (meaning more malignant or more benign), the team works together to define a treatment plan that is different depending on whether the tumor is felt to be at low-, intermediate-, or high-risk of coming back or spreading (metastasizing) to other sites.

Advanced Treatments

Treatment for non-rhabdomyosarcomas requires several levels of therapy and it is "risk-based," meaning that the treatment is tailored to the level of risk for tumor recurrence or metastasis. There are essentially three types of therapy that can be used individually or in combination: surgery, radiation therapy, and chemotherapy.

Surgery -- to remove the cancer and a margin of healthy tissue surrounding it. If the tumor is in an arm or leg, it is sometimes necessary to amputate all or part of the limb; however, this is relatively rare. In some cases, especially small and low-grade NRSTS that have not spread, surgery may be the only treatment.

Radiation therapy -- can be given before surgery to shrink the tumor or after surgery to kill any remaining cancer cells that may have been left at the "margin" of the tumor. Radiation is sometimes used if it is not possible to remove the entire tumor without an amputation. Radiation is usually reserved for higher-grade NRSTS which are more likely to come back following surgical removal.

Chemotherapy -- is given to try to shrink the tumor and make it more accessible for surgery or radiation therapy, and also to prevent the tumor from coming back. Historically, most types of NRSTS have responded poorly to chemotherapy. However, there are some newer medicines that attack specific targets in the NRSTS.

Some patients may be eligible for studies of the very newest therapies through clinical trials being conducted at the University of Chicago Medicine Comer Children's Hospital. The clinical trials are conducted because we are not sure if the newest therapies are the best ones. Parents are closely involved in deciding whether or not to enroll their child in a clinical trial. Clinical trials are only considered by the sarcoma team if they are thought to provide the best chance to cure the non-rhabdomyosarcoma soft tissue sarcoma.