Outcomes in lung-only metastatic rhabdomyosarcoma: An analysis of data from the European paediatric Soft tissue sarcoma Study Group MTS 2008 study

Purpose: Patients with metastatic rhabdomyosarcoma (MTS RMS) and lung as the only metastatic site have better reported outcomes than other patients with MTS RMS. We analysed patients with lung-only MTS RMS receiving standard treatment within the EpSSG MTS 2008 protocol. Patients and methods: Previously untreated patients aged< 21 years with MTS RMS received standard induction chemotherapy with radiotherapy (RT) and/or surgery to the primary site and RT recommended to all metastatic sites. Clinical characteristics, treatment and outcomes of patients with lung-only MTS RMS were compared to lung + other site and other site MTS RMS. Results: Among 270 patients with MTS RMS, 59 (22%) had lung-only metastatic disease, 68 (25%) in lung + other and 143 (53%) in other sites. 3-yr Event Free Survival (EFS) and Overall Survival (OS) for lung-only MTS RMS were 40% (95%CI 27–53%) and 60% (95%CI 46–71%). Although 3-yr OS for lung-only MTS RMS was significantly better than lung + other (35%; 95% CI 24–47%) and other (49%; 95% CI 40–57%) sites (p = 0.0382), EFS and OS adjusted for known clinical (Oberlin) risk factors, did not differ between the groups. 3-year EFS was significantly higher in patients with lung-only MTS who received RT to the lungs (RT, n = 26, EFS 56%, 95% CI 35–73%; no RT, n = 24, EFS 33%, 95% CI 16–52%, p = 0.0435). Conclusions: Better outcomes for lung-only MTS RMS seem to be determined by the presence of fewer clinical risk factors. Whole lung radiotherapy continues to be recommended in patients with lung-only MTS RMS.