Local control for Intermediate-Risk Rhabdomyosarcoma: Results from D9803 according to Histology, Group, Site and Size: A Report from the Children’s Oncology Group
Menée sur 423 patients pédiatriques atteints d'un rhabdomyosarcome embryonnaire ou alvéolaire à risque intermédiare de récidive (âge médian : 5 ans ; durée médiane de suivi : 6,6 ans), cette étude évalue l'efficacité, du point de vue du contrôle local de la maladie et en fonction des caractéristiques tumorales, de protocoles thérapeutiques comportant une chimiothérapie de type VAC, en alternance ou non avec une chimiothérapie de type VTC, et une radiothérapie
Purpose : To determine local control based on clinical variables for patients with intermediate-risk rhabdomyosarcoma (RMS) treated on Children’s Oncology Group (COG) protocol D9803. Methods : Of 702 patients enrolled, we analyzed 423 patients with central pathology–confirmed group III embryonal (n=280) or alveolar (Group III, n=102; Group I-II, n=41) RMS. Median age was 5 years. Patients received 42 weeks of VAC (vincristine, dactinomycin, cyclophosphamide) or VAC alternating with VTC (T = topotecan). Local therapy with 50.4 Gy radiation therapy (RT) ± delayed primary excision began at week 12 for Group III patients. Patients with Group I/II alveolar RMS received 36-41.4 Gy. Local failure (LF) is defined as local progression as a first event with or without concurrent regional or distant failure. Results : At median follow-up of 6.6 years, patients with Clinical Group I/II alveolar RMS had a 5-year event-free survival (EFS) rate of 69% and LF of 10%. Among patients with Group III RMS, 5-year EFS and LF was 70% and 19%, respectively. LF rates did not differ by histology, nodal status, or primary site, though there was a trend for increased LF for retroperitoneal (RP) tumors (P=.12). Tumors ≥5 cm were more likely to fail locally than tumors <5 cm (25% vs. 10%, P=.0004). Almost all (98%) RP tumors were ≥5 cm with no difference in LF by site when the analysis was restricted to tumors ≥5 cm (P=.86). Conclusion : Local control was excellent for Clinical Group I/II alveolar RMS. LF constituted 63% of initial events in Clinical Group III patients and did not vary by histology or nodal status. The trend for higher LF in RP tumors was related to tumor size. There has been no clear change in local control over RMS studies including IRS-III and IRS-IV. Novel approaches are warranted for larger tumors (>5 cm).