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The exact cause of most cases of rhabdomyosarcoma (RMS) is not known. Scientists have found some risk factors, but most people with RMS do not have any known risk factors.
While there are a few known risk factors for rhabdomyosarcoma (RMS), the cause of most RMS is not known. Researchers are learning how changes in DNA can cause normal cells to become cancer. This may lead to finding better ways to prevent and treat cancers like RMS.
DNA is the chemical in each of our cells that makes up our genes. Genes control how our cells function. Changes (mutations) in the DNA inside our cells can sometimes change the way some genes work, which can promote cancer growth.
Some genes control when our cells grow, divide into new cells, and die:
To learn more, see Oncogenes, Tumor Suppressor Genes, and DNA Repair Genes.
Gene changes that make the IGF2 gene overactive play an important role in tumor growth in embryonal rhabdomyosarcoma (ERMS). Changes to IGF2 are seen in other types of RMS as well. Research to find gene changes specific to ERMS is ongoing.
Gene changes that make the PAX genes overactive are an important part of many cases of ARMS. The PAX genes play a role in cell growth when muscle tissue is being formed before birth, but these genes usually turn off when they are no longer needed. When cells grow and divide, sometimes pieces of DNA can be swapped between two chromosomes, the long strands of DNA in each cell. This process, called a translocation, can move one of the PAX genes next to the FOXO1 gene, which keeps the PAX gene on. This leads to a gene change called a PAX/FOXO1 fusion and causes tumor growth.
Not all ARMS has the PAX/FOXO1 fusion gene. In fact, about 1 out of 5 cancers that look like ARMS under the microscope have been found not to have the PAX/FOXO1 fusion gene typically seen in ARMS. Doctors have found that fusion-negative ARMS acts more like ERMS, which generally requires less intense treatment and has a better outlook.
Gene changes define 3 subtypes of spindle cell/sclerosing type RMS and can help doctors anticipate a child’s outlook. For example, gene changes in VGLL2 and NCOA2 have been seen in infants less than 1 year of age and have very good outcomes. Older children may have RMS with gene changes in MYOD1 which is more difficult to treat.
Changes in several different genes are usually needed for normal cells to become cancer cells. Scientists have found some other gene changes that set some RMS cells apart from normal cells, but there are likely still others that have not been defined yet.
A risk factor is anything that affects the chance of having a disease such as cancer. Different cancers have different risk factors.
Unlike adult cancers, lifestyle-related risk factors such as body weight, physical activity, diet, and the use of tobacco and alcohol do not play a major role in pediatric cancers. In many cases, researchers do not know what causes cancers like RMS in younger people.
RMS is most common in children younger than 10, but it can also develop in teens and adults. It is slightly more common in boys than in girls.
Some people develop certain types of cancer because they have inherited changes in their DNA (genes) from their parents. Some rare inherited conditions increase the risk of RMS (and usually some other tumors as well):
These conditions are rare and account for only a small number of RMS cases. But they suggest that the key to understanding RMS might come from studying genes and how they work in very early life to control cell growth and development.
Some studies have suggested that being exposed to x-rays before birth might be linked with an increased risk of RMS in young children. Parental use of drugs such as marijuana and cocaine has been suggested as a possible risk factor as well. But these studies were small, and more research is needed to see if these factors are truly linked to RMS.
Researchers now understand many of the gene changes that can lead to RMS, but it is still not clear what causes these changes. Some gene changes can be inherited from a parent. Others might just be a random event that happens inside a cell, without having an outside cause. There are no clear lifestyle-related or environmental causes of RMS, so it is important to know that there is nothing children with RMS or their parents could have done to prevent these cancers.
Currently, there are no known ways to prevent most cancers in children.
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
Linardic CM, Wexler, LH. Chapter 25: Rhabdomyosarcoma. In: Blaney SM, Adamson PC, Helman LJ, eds. Pizzo and Poplack’s Principles and Practice of Pediatric Oncology. 8th ed. Philadelphia Pa: Lippincott Williams & Wilkins; 2021.
National Cancer Institute. Childhood Rhabdomyosarcoma Treatment (PDQ®). 2024. Accessed at www.cancer.gov/types/soft-tissue-sarcoma/hp/rhabdomyosarcoma-treatment-pdq on April 3, 2025.
Okcu MF, Hicks J, Lupo, PJ. Rhabdomyosarcoma in childhood and adolescence: Epidemiology, pathology, and molecular pathogenesis. UpToDate. 2025. Accessed at www.uptodate.com/contents/rhabdomyosarcoma-in-childhood-and-adolescence-epidemiology-pathology-and-molecular-pathogenesis on April 3, 2025.
Williamson D, Missiaglia E, de Reyniès A, et al. Fusion gene-negative alveolar rhabdomyosarcoma is clinically and molecularly indistinguishable from embryonal rhabdomyosarcoma. J Clin Oncol. 2010;28:2151-2158.
Last Revised: June 2, 2025
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