Prognostic factors and survival outcomes in patients undergoing limb-sparing surgery for primary malignant bone tumors.

Background: Primary malignant bone tumors are aggressive neoplasms that frequently affect adolescents and young adults. Limb-sparing surgery (LSS) has become the preferred surgical approach when oncologically feasible; however, survival outcomes vary considerably, and robust prognostic indicators remain essential for risk stratification and follow-up planning. Aim: To evaluate clinical, laboratory, surgical, and histopathological factors associated with survival and functional outcomes in patients with primary malignant bone tumors treated with limb-sparing surgery. Materials and methods: This retrospective cohort study included 110 patients with histologically confirmed primary malignant bone tumors who underwent LSS at a tertiary orthopedic oncology center. All patients were free of distant metastasis at baseline. Clinical, imaging, laboratory, surgical, and pathological variables were analyzed. Tumor necrosis was assessed only in patients receiving neoadjuvant chemotherapy. Survival outcomes were evaluated using Kaplan-Meier analysis, and Cox proportional hazards regression was performed with exclusion of post-baseline events from baseline models to avoid time-dependent bias. Functional outcomes were assessed using the Musculoskeletal Tumor Society (MSTS) and Toronto Extremity Salvage Score (TESS). The median follow-up duration was 36 months (IQR: 24-60 months). Results: During follow-up, 27 deaths (24.55%), 17 local recurrences (15.45%), and 28 distant metastatic events (25.45%) were recorded. The overall survival rate at last follow-up was 75.45%, and the disease-free survival rate beyond two years was 67.27%. Favorable survival was significantly associated with tumor necrosis >90%, wide surgical margins, and lower serum LDH levels. In multivariable analysis, tumor necrosis ≤90% (HR 2.84), non-wide surgical margins (HR 2.47), elevated LDH (HR 2.12), and high Ki-67 index (HR 2.28) were independently associated with reduced overall survival. Good functional outcomes (MSTS ≥24) were achieved in 62.73% of patients, and 65.45% attained TESS scores >70. Conclusion: Limb-sparing surgery can provide satisfactory oncologic and functional outcomes in selected patients with primary malignant bone tumors. Survival outcomes were independently associated with tumor response to chemotherapy, surgical margin status, and tumor biology. Given the heterogeneity of bone sarcoma subtypes, these findings should be interpreted with caution and regarded as hypothesis-generating, supporting individualized multidisciplinary management strategies.