Multimodale behandeling bij gemetastaseerd niet-rhabdomyosarcoma weke-deel sarcoom resulteert in 5-jaars overleving van 36% bij kinderen en jongvolwassenen

BACKGROUND: We evaluated clinical characteristics, response to therapy, event-free and overall survival (EFS and OS), patterns of recurrence/progression, and factors associated with survival in patients with metastatic non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) treated on the Children's Oncology Group ARST0332 trial. METHODS: All patients with metastatic disease enrolled in ARST0332 were included. Treatment involved multimodal therapy with ifosfamide and doxorubicin, surgery ± radiotherapy. EFS was time from enrollment to progression, recurrence, second malignancy, or death; OS was defined as the time to death from any cause. RESULTS: The analysis included 80 patients, with synovial sarcoma as the most common histology (n = 21, 26%). Two-thirds of patients (n = 60) had >1 metastatic site, with the lung being the most common site of metastasis. At the week 13 therapy timepoint, response rate [complete or partial response (CR/PR)] was 41%, and 11% of patients had progressive disease. At a median follow-up of 7.5 years, 61 patients had relapse or progression, most commonly occurring at metastatic sites present at diagnosis (41%), followed by new metastatic sites (11%). The 5-year EFS and OS were 21% [95% Confidence Intervals (CI), 11 to 31] and 36% (95% CI, 24 to 47), respectively. In univariable analysis, histologic subtype was associated with EFS, whereas having a single metastatic site and achieving CR or PR at week 13 were associated with improved EFS and OS (p < 0.05). CONCLUSION: Survival of pediatric metastatic NRSTS remained dismal on ARST0332. Prognosis varied by histology, metastatic burden, and early treatment response, underscoring the urgent need for novel biologically informed, response-adapted treatment strategies.