The treatment of rhabdomyosarcoma has come a long way in the past 30 years, largely due to the work of the Intergroup Rhabdomyosarcoma Study Group (now known as the Soft Tissue Sarcoma Committee of the Children's Oncology Group). However, more work needs to be done.
Better classification of rhabdomyosarcomas
Newer molecular techniques may help better categorize rhabdomyosarcomas and predict which patients will respond best to certain treatments. For example, rather than just looking at the cancer cells under a microscope, researchers have begun to use specialized genetic tests to help classify rhabdomyosarcomas. About 25% of cancers that doctors would usually classify as alveolar rhabdomyosarcoma (ARMS) have been found to lack the typical gene change (the PAX/FKHR fusion gene) seen in ARMS. Some early studies have shown that these cancers seem to act more like embryonal rhabdomyosarcoma (ERMS) than ARMS. ERMS generally requires less intensive treatment than ARMS. If this finding is confirmed in other studies, it may allow doctors to use less intensive treatments on these cancers and still achieve the same results.
Improving standard treatments
A major goal of current research is to more effectively treat all patients, while reducing exposure to intensive treatments (and their side effects) when possible. For example, researchers are studying whether children who have a low risk of the tumor recurring can be successfully treated without using potentially harmful therapies such as the chemotherapy drug cyclophosphamide and radiation therapy.
Because children's bodies are very sensitive to radiation, doctors are looking for ways to limit the doses as much as possible. Newer radiation therapy techniques allow doctors to aim the radiation more precisely, limiting the amount that reaches normal body tissues. Some of these techniques were described in the section "How is rhabdomyosarcoma treated?", and other approaches are now being studied. For example, in stereotactic radiation therapy, a special machine allows the radiation to be aimed at the tumor from many different angles.
Proton beam radiation is another new approach. Standard radiation beams give off the same amount of radiation at all points in the body as they pass through it. Proton beam radiation uses radioactive particles that travel only a certain distance before releasing most of their energy. Doctors can use this property to limit the radiation reaching normal body tissues. While this new approach seems promising, it is expensive and is only available in a handful of centers around the country at this time.
Doctors are studying adding newer chemotherapy drugs such as irinotecan to the standard VAC chemotherapy regimen in those who have a higher risk of the tumor recurring.
For patients at a high risk of tumor recurrence, the goal is to maximize the early treatment with drugs such as cyclophosphamide and ifosfamide by giving them more frequently (a concept called "interval compression").
Newer treatment approaches
Drugs that target specific parts of cancer cells (as opposed to just attacking fast-growing cells) are now being used to treat some adult cancers. Some of these drugs, such as dasatinib (Sprycel), are now being studied for use in rhabdomyosarcoma as well.
Some other newer drugs also work in ways that are different from standard chemotherapy drugs. Trabectedin (ET-743) and IGF-1 receptor inhibitors are examples of such drugs now being tested clinical trials.
Researchers are also testing other new ways to treat rhabdomyosarcoma. For example, some researchers are looking at exposing some of the body's own immune system cells, called dendritic cells, to the abnormal PAX-FKHR protein that is found in many ARMS cells. The hope is that the dendritic cells will then cause the immune system to attack these cells, no matter where they are in the body.
Other new approaches, including the use of monoclonal antibodies (manmade versions of immune system proteins), may also prove to be effective against rhabdomyosarcoma.
Eventually, a combination of these approaches may prove to be the best way to treat this disease.
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