Embryonal rhabdomyosarcoma with metastases confined to the lungs: report from the CWS Study Group

Embryonal rhabdomyosarcoma [RME] is the most common pediatric soft tissue sarcoma. Whereas the prognosis of localized rhabdomyosarcoma has improved, it remains poor for metastatic disease.

We analyzed RME-patients with isolated pulmonary metastases [PRME] treated in four consecutive CWS-trials. Treatment included multiagent chemotherapy and local treatment of the primary tumor. Therapy of lung metastases after induction chemotherapy depended on response and individual decisions.

Twenty-nine patients <21 years had PRME. Their median age was six years, the median follow-up nine years. Twenty-eight children had their primary tumor located in an unfavorable site and 22 of the primaries were >5 cm. In addition to conventional chemotherapy, seven patients received high-dose treatment and eight patients oral metronomic chemotherapy. The lung metastases were in remission after induction chemotherapy in 22 individuals. 19 patients received no local treatment of metastases; 3 patients had pulmonary metastasectomy and lung radiation was administered to 9 individuals. In total, 24/29 patients achieved a complete remission [CR]. Actuarial 5-year event-free and overall survival for all patients was 37.9 ± 18% and 48.7 ± 18%, respectively; it was 45.8 ± 20% and 58.3 ± 20% for the 24 patients who achieved a CR. Local treatment of metastases had no impact on the failure pattern. Younger age, good response, achievement of CR and maintenance-treatment were favorable prognostic factors in univariate analysis.

Children with PRME have a fair prognosis. Local treatment of metastases did not improve outcome in our sample. Metronomic treatment may be an attractive option for PREM-patients.