Age-related real-world treatment patterns and outcomes of localised, high-grade osteosarcoma.

Introduction: There is currently no consensus regarding the standard treatment for osteosarcoma arising in middle-aged and older patients. We aimed to evaluate real-world treatment patterns and oncological outcomes using a nationwide Japanese database and to clarify optimal age-adapted treatment strategies. Methods: A total of 871 patients with localised, high-grade osteosarcoma registered between 2011 and 2020 in the Japanese Bone and Soft Tissue Tumour Registry were analysed. Treatment patterns and disease-specific survival (DSS) were evaluated according to age groups (≤ 40 years, n = 615; 41-64 years, n = 154; and ≥ 65 years, n = 102). Results: Trunk tumours were significantly more frequent in patients aged 41-64 (30%) and ≥ 65 years (40%) than in those aged ≤ 40 years (5%). Definitive surgery rates decreased with age (98%, 91%, and 85%, respectively). Perioperative chemotherapy was administered in 92%, 79%, and 34% of patients, with reduced use of methotrexate and cisplatin in patients aged > 40 years. Multivariable analysis identified age ≥ 65 years, absence of surgery, palliative chemotherapy, and adjuvant or palliative radiotherapy as adverse prognostic factors. The 5-year DSS was 79%, 62%, and 45% in patients aged ≤ 40, 41-64, and ≥ 65 years, respectively ( Conclusion: Wide/radical resection combined with perioperative chemotherapy remains the mainstay of treatment regardless of age in osteosarcoma management. The optimal sequencing of chemotherapy and surgery warrants a prospective international collaborative study.