The outcomes and prognostic factors in patients with osteosarcoma according to age: a Japanese nationwide study with focusing on the age differences

BACKGROUND: Few reports have described clinical features, prognosis and prognostic factors of osteosarcoma patients according to age. METHODS: Using the Bone and Soft Tissue Tumor Registry in Japan, we identified 1043 osteosarcoma patients including 760 who were younger than 40 years, 173 aged between 41 and 64 years, and 110 patients older than 65 years. We extracted data on patient demographics and prognosis. Prognostic factors for patients older than 65 years or other age groups were analyzed. RESULTS: Patients older than 65 years showed a significantly higher proportion of tumors arising in the trunk and with metastasis at diagnosis, and their 5-year disease-specific survival (DSS) rate was 32.7%. Multivariate analysis showed that the presence of metastasis at diagnosis [hazard ratio (HR): 3.04; 95% confidence interval (CI), 1.63–5.69; P < 0.001] and tumors > 16 cm in size (HR: 2.84 compared with < 8 cm; 95% CI, 1.16–6.97; P = 0.023) were significantly associated with worse DSS. The 5-year DSS was 39.1% in 80 patients older than 65 years without metastasis at diagnosis. Methotrexate was used in only 5.0% of these patients. Adjuvant chemotherapy was not significantly associated with better DSS (P = 0.323) in this generation and aged between 41 and 64 years (P = 0.566), although adjuvant chemotherapy yielded significantly better survival in patients younger than 40 years (P < 0.001). CONCLUSIONS: Analysis of this cohort of osteosarcoma patients revealed some unique clinical, therapeutic and prognostic features according to age groups in the largest cohort. Adjuvant chemotherapy was not associated with a better DSS in the group of patients aged between 41 and 64 years or older than 65 years.