Previously Untreated Childhood Rhabdomyosarcoma
Because rhabdomyosarcoma can arise from multiple sites, surgical care decisions and radiotherapeutic options must be tailored to the specific aspects of each site, and should be discussed with a multidisciplinary team including representatives of those specialties, as well as pediatric oncologists. Surgical management of the more common primary sites is provided in the Local Control Management with Surgery and RT by Primary Sites of Disease section of this summary.
Local Control Management: Radiation Therapy (RT)
Only 15% of patients present with Group I, completely resected disease, so RT is used in the majority of cases.
RT is an effective method for achieving local control of the tumor for patients with microscopic or gross residual disease following biopsy, initial surgical resection, or chemotherapy. Patients with completely resected embryonal rhabdomyosarcoma (Group I) do well without RT. An earlier study of Group I patients with alveolar rhabdomyosarcoma and undifferentiated soft tissue sarcoma found that omission of RT was followed by decreased local control. A subsequent review of patients with only alveolar rhabdomyosarcoma found that the improvement in outcome with RT did not reach statistical significance for patients with Stage 1 and 2 tumors. There were very few patients (n = 4) with large tumors (Stage 3, >5 cm) who did not receive RT, but their outcome was poor.[Level of evidence: 3iiiDii]
In more than 50% of Group II rhabdomyosarcoma patients, local recurrence was due to noncompliance with guidelines or omission of RT. A review of European trials conducted by the German Cooperative Weichteilsarkom Studien (CWS) Group between 1981 and 1998, in which RT was omitted for some Group II patients, demonstrated a benefit to using RT as a component of local tumor control for all Group II patient subsets, as defined by tumor histology, tumor size, and tumor site.
The predominant type of relapse for patients with Group III disease is local failure. Patients with tumor-involved regional lymph nodes at diagnosis also have a higher risk of local and distant failure compared with patients whose lymph nodes are uninvolved. As with the surgical management of patients with rhabdomyosarcoma, recommendations for RT depend on the site of primary tumor, the postsurgical (if performed) amount of residual disease (none vs. microscopic vs. macroscopic), and the presence of involved lymph nodes.