Outcomes in paediatric metastatic rhabdomyosarcoma: Results of The International Society of Paediatric Oncology (SIOP) study MMT-98

Abstract

Purpose Results are presented of the SIOP study MMT-98 for paediatric metastatic rhabdomyosarcoma (RMS), which evaluated intensive chemotherapy followed by low intensity ‘maintenance’ chemotherapy in standard risk patients (SRG). For poor risk patients (PRG), the value of a therapeutic window study, sequential high dose monotherapy to achieve a complete response (CR) followed by low dose maintenance chemotherapy was examined. Patients and methods From November 1998 to 2005, 146 patients aged 6 months to 18 years with metastatic RMS were entered. Forty-five were SRG, i.e. age < 10 years and no bone marrow or bone involvement. Treatment was a 6-drug regimen with local therapy of surgery and/or radiotherapy followed by maintenance of 9 courses of vincristine, actinomycin D and cyclophosphamide (VAC). One hundred and one patients were PRG, i.e. >10 years, or with bone marrow or bone metastases. An upfront window study, high dose monotherapy, local treatment and then VAC maintenance therapy were given. Results With a median follow-up of 1.52 years, the 3-year event-free survival (EFS) and overall survival (OS) for SRG were 54.92% and 62.14%, respectively, whilst for the PRG 16.17% and 23.17%. The corresponding adverse hazard ratio (HR) for the PRG was HR = 2.65 (95% CI 1.63–4.31, p-value < 0.001) for EFS and HR = 2.51 (CI 1.53–4.11, p-value < 0.001) for OS. Conclusion SRG patients’ EFS and OS were comparable to those of previous studies. For PRG patients there was no improvement in survival.