Metastatic osteosarcoma, patterns of care and outcomes of patients in a real-life national setting over a decade.

Metastatic osteosarcoma (MOS) has a poor prognosis, and few treatment options. This multicentre observational study provides real-world data on treatment patterns of patients with MOS in France. The primary objective was to describe treatment modalities of patients with MOS aged ≥12 years treated in 11 reference network centers. Secondary objectives were to assess time to next treatment (TTNT), overall survival (OS) and prognostic factors for TTNT and OS. From 2008 to 2018, 262 patients with MOS were included; 88 patients were metastatic at diagnosis, and 174 patients had a metastatic relapse. Median age at diagnosis was 26 (12-86). A total of 227 (86.6%) patients received systemic treatment in the metastatic setting, and 75 (28.6%) patients received more than two lines. Overall, 153 (58.4%) patients underwent at least a loco-regional procedure, and 50 patients (19.1%) participated in a clinical trial in the metastatic setting. Median OS from metastasis diagnosis was 21.5 months [95% CI 18.9-27.0], 23.0 months [95% CI 15.0-31.1] in the synchronous cohort, and 21.4 months [95% CI 18.7-29.7] in the metachronous cohort. Median TTNT was 8.2 months [95% CI 6.7-9.9], 5.7 months [95% CI 4.2-7.2], 3.7 months [95% CI 3.0-4.3], and 2.9 months [95% CI 1.8-3.9] in first, second, third, and fourth line. It was 7.6 months [95% CI 5.1-12.5], 6 months [95% CI 3.6-8.7], and 4.8 months [95% CI 2.9-7.5] for tyrosine kinase inhibitors such as regorafenib or cabozantinib in first, second, and third line. In MOS, the benefit of chemotherapy after first line is limited. TKIs show encouraging activity from first line. Inclusion in clinical trials should be prioritized.