The impact of whole lung irradiation in lung metastatic rhabdomyosarcoma: A pooled analysis of two European trials and one European registry.

BACKGROUND

Lung metastases in patients with metastatic rhabdomyosarcoma (RMS) have not been treated uniformly across Europe. This provides comparison of the impact of whole lung irradiation (WLI).

METHODS

Lung-metastatic patients included in the Cooperative Weichteilsarkom Studiengruppe-IV 2002, European Pediatric Soft Tissue Sarcoma Study Group MTS 2008 or the Soft Tissue Sarcoma Registry received four- or six-drug chemotherapy, surgery, and/or irradiation (radiotherapy) of the primary tumor. Treatment of lung lesions consisted of metastasectomy, WLI, or no local treatment according to protocols.

RESULTS

A total of 238 patients with lung-metastatic RMS were included. Half of these patients (n = 119/238) had lung metastases only (median age, 6.6 years), mainly classified as embryonal RMS (n = 93/119, 78%). Lung-only patients underwent metastasectomy (n = 17) and/or WLI (n = 31) or no local treatment of lung metastases (n = 71). Early complete response of lung metastases was associated with favorable 3-year overall survival (p = .009). A trend toward improved event-free survival after WLI could be identified in patients ≥10 years old (hazard ratio [HR], 2.7; 95% CI, 0.8-9.6), but not in patients under 10 years old (HR, 0.86; 95% CI, 0.44-1.66). Lung-relapse-free survival (lung-RFS) was not influenced by WLI or metastasectomy in the univariable and multivariable analyses. When analyzing all lung-metastatic patients (including those with metastases in other sites, n = 238), WLI in patients older than 10 years was a significant prognostic factor (HR, 2.2; 95% CI, 1.0-4.9).

CONCLUSIONS

The analysis failed to show a significant benefit of WLI in patients with lung-metastatic RMS, apart from the subgroup of patients older than 10 years. Lung-RFS was not influenced by WLI.