RT (Local Control Management)

Group I: Patients with completely resected embryonal rhabdomyosarcoma at diagnosis before initiation of chemotherapy do well without RT. However, because approximately 75% of embryonal rhabdomyosarcoma patients are Groups II to IV, RT is used in most patients.[11]A study of Group I patients with alveolar rhabdomyosarcoma and undifferentiated soft tissue sarcoma found that omission of RT was followed by decreased local control.[12] 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 Stage 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.[13][Level of evidence C2] COG recommends the use of RT for all patients with FOXO1 fusion–positive disease (previously called alveolar rhabdomyosarcoma).

Group II: In more than 50% of Group II rhabdomyosarcoma patients, local recurrence was the result of noncompliance with guidelines or omission of RT.[14] The German Cooperative Weichteilsarkom Studiengruppe (CWS) conducted a review of European trials between 1981 and 1998, in which RT was omitted for some Group II patients. This review 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.[15]

Group III: The predominant type of relapse for patients with Group III disease is local failure. Approximately 35% of patients with Group III disease either fail to achieve a complete remission or relapse locally. Patients with tumor-involved regional lymph nodes at diagnosis also have a higher risk of local and distant failure than do patients whose lymph nodes are uninvolved.[16]

In the subgroup of patients who received RT as the only local treatment (n = 278), significant positive prognostic factors included no intracranial tumor extension and complete remission at the end of treatment.

No significant differences in tumor outcomes were seen between the different RT concepts.

RT can be omitted in patients with IRS Group I embryonal rhabdomyosarcoma (fusion-negative rhabdomyosarcoma).

RT improves EFS and local control survival (LCS) in patients with IRS Groups II and III disease.

Patients with tumors in the head and neck region (orbital, parameningeal, and nonparameningeal) and in other sites who received proton RT had EFS and LCS that were comparable with those of patients who received photon RT. Patients with parameningeal tumors had an improved OS with proton RT.

The efficacy of low RT doses of 32 Gy (HART) and 36 Gy to 41.4 Gy (conventional fractionated RT [CFRT]) in the favorable-risk groups of patients and higher doses of 44.8 Gy (HART) and 50.4 Gy to 55.4 Gy (CFRT) in the unfavorable-risk group of patients was comparable.