The prognostic value of early radiographic response in children and adolescents with embryonal rhabdomyosarcoma stage IV, metastases confined to the lungs: A report from the Cooperative Weichteilsarkom Studiengruppe (CWS)
Patients with metastatic rhabdomyosarcoma (RMS) have a poor prognosis apart from children with embryonal RMS whose metastases are confined to the lungs (PRME). The prognostic significance of response in patients with metastatic disease is still unknown and optimal treatment remains to be defined.Methods
Patient-, tumor- and treatment-related factors of patients with PRME treated on multiple prospective trials of the Cooperative Weichteilsarkom Studiengruppe (CWS) (1981–2013) were analyzed with a focus on response to induction chemotherapy. Response at week 7–10 was based on anatomic imaging and determined (1) for the primary tumor as complete response (CR), good response (GR), partial response (PR) and no response (NR) and (2) for pulmonary metastases as either complete lack of residual lesions (pCR) or no complete response (no-pCR). Event-free (EFS) and overall survival (OS) were the endpoints.Results
EFS and OS of all 53 eligible patients was 41% (±13 confidence interval [CI] 95%) and 52% (±11 CI 95%), respectively. pCR at week 7–10 and maintenance therapy (MT) were favorable prognostic factors. Interestingly, response of primary tumor at week 7–10 and number of metastases were not prognostic factors. The 5-year OS was 68% (±18 CI 95%) for 26 patients in pCR, but only 36% (±18 CI 95%) for 27 patients not in pCR at week 7–10 (P = 0.004) despite achieving pCR under continuation of chemotherapy or local therapy.Conclusion
Achievement of pCR at week 7–10 by induction chemotherapy is a prognostic factor.