Epidemiology
Rhabdomyosarcoma is the most common soft-tissue sarcoma in children as well as the third most common solid tumor in children. Recent estimates place the incidence of the disease at approximately 4.5 case per 1 million children/adolescents with approximately 250 new cases in the United States each year. With the vast majority of cases of RMS occurring in children or adolescents, two-thirds of reported cases occur in youths under the age of 10. RMS also occurs slightly more often in males than in females, with a ratio of approximately 1.3–1.5:1. In addition, slightly lower prevalence of the disease has been reported in black and Asian children relative to white children. In most cases, there are no clear predisposing risk factors for the development of RMS. It tends to occur sporadically with no obvious cause. However, RMS has been correlated with familial cancer syndromes and congenital abnormalities including neurofibromatosis type 1, Beckwith-Wiedemann syndrome, Li–Fraumeni syndrome, cardio-facio-cutaneous syndrome, and Costello syndrome. It has also been associated with parental use of cocaine and marijuana. History
Rhabdomyosarcoma was first described by Weber, a German physician, in 1845, but it wasnt until the paper by Arthur Stout in 1946 that RMS was formally classified. The first thirty years of investigation were conducted by the Intergroup Rhabdomyosarcoma Study Group (IRSG), an independent National Cancer Institute (NCI)-funded cooperative that has become a part of the Childrens Oncology Group. Research
Cancer stem cells of rhabdomyosarcoma have been identified and fibroblast growth factor receptor 3 has been suggested as their marker.
The fourth IRSG study found that 23% of patients were diagnosed in time for a complete resection of their cancer, and 15% had resection with only minimal remnants of the diseased cells. Risk factors
Rhabdomyosarcoma is difficult to diagnose. Risk factors that increase the likelihood of this cancer include inherited disorders such as Li-Fraumeni syndrome, Neurofibromatosis type 1, Beckwith-Wiedemann syndrome, Costello syndrome, Noonan syndrome, and DICER1 syndrome. Genetic
There are multiple genetic lesions associated with rhabdomyosarcoma, but there has been little consistent data demonstrating an association between specific genetic abnormalities and outcome. However, alveolar and embryonal types of RMS can be distinguished cytogenetically, and identification of specific genetic lesions can allow for accurate classification of the ARMS subtype when the histopathological findings are equivocal or unclear. This is valuable for clinical practice as the alveolar type presents a higher risk to the patient and will often require more aggressive treatment than the embryonal type. Thus, ARMS is also referred to as Fusion Positive rhabdomyosarcoma (FP-RMS). Up to 90% of alveolar RMS cases present with a translocations of t(2;13)(q35, q14) or, less commonly, t(1;13)(p36, q15). Both involve the translocation of a DNA binding domain of either PAX3 or PAX7, a member of the Paired Box family of transcription factors, to a transactivation site on FOXO1 (previously known as FKHR), a member of the forkhead/HNF-3 transcription factor family. The t(2;13) translocation results in a fusion of the PAX3 gene with FOXO1, while the t(1;13) translocation involves the fusion of PAX7 with FOXO1.