Beyond 5‐year survival. A report from the Cooperative Osteosarcoma Study Group (COSS)

Purpose Prognostic factors have been well described for osteosarcoma, but analyses evaluating the further course of long‐term survivors are lacking. We used the large database of the Cooperative Osteosarcoma Study Group (COSS) to perform such an analysis. Patients and Methods The COSS database 1980‐04/2019 was searched for 5‐year survivors of primary high‐grade central osteosarcoma of the extremities or trunk. Identified patients were analyzed for their further survival outcomes, assessing potentially prognostic and predictive factors already evident at initial disease presentation and treatment as well as their disease course during the first 5 years of follow‐up. Results Two thousand and nine former eligible patients were identified (median age at initial diagnosis 15.1 (2.5–63.0) years; male vs. female 1149 (57.2%) vs. 860 (42.8%); extremities vs. trunk 1927 (95.9%) vs. 82 (4.1%); extremity primaries