Intermediate-risk rhabdomyosarcoma (RMS) is:
- Non-metastatic (Group I-III) alveolar (RMS) arising at any site (Stage 1-3)
- Incompletely excised (Group III) embryonal RMS arising in an unfavorable site (Stage 2,3).
The long-term failure-free survival (FFS) for intermediate-risk RMS, as defined above, is still only 65%.
To improve long-term survival, the current COG research study ARST0531 compares standard VAC chemotherapy versus VAC alternating with vincristine and irinotecan (VI). RT begins at week 4 in conjunction with VI to determine the potential benefit of early local therapy in this group of patients. The outcome of patients randomly assigned to either standard vincristine, dactinomycin, and cyclophosphamide (VAC) chemotherapy or VAC alternating with vincristine and irinotecan (VI) will be compared.
- The cumulative dose of cyclophosphamide in the VAC arm of this study is lower than the previous IRS-III and IV studies (16.8 g/m2 vs 23.4g/m2 and 26.4g/m2 respectively). It is unknown whether this will affect survival or acute and chronic toxicity related to this drug).
- RT starts early at Week 4 (compared to week 13 in the low risk study) for most all patients.
- The long-term morbidity of RT or aggressive surgery for very young (≤ 24 months old) children makes local control very challenging. The COG study permits deviations at the discretion of the treating clinicians in these very young patients.
- Guidelines for GTV, CTV and PTV same as low risk protocol.
Clinical Group and required RT Total Dose:
| Clinical Group | Total Dose |
I |
Alveolar only 36 Gy
|
| II | Node negative 36 Gy |
| II | Node positive 41.4 Gy |
| III | Alveolar, orbit only 45 Gy |
| III | all other sites 50.4 Gy |
