(P 54) CHONDROBLASTIC OSTEOSARCOMA IS A RISK FACTOR FOR LOCAL RECURRENCE IN PATIENTS WITH SKELETAL OSTEOSARCOMA

Objective: Osteosarcoma is the most common primary malignant bone tumor with an incidence of 3-4 per million people per year. Despite advancements in the management, the risk of local recurrence in osteosarcoma poses a significant challenge, given its association with mortality. Thus, this study aims to identify risk factors for local recurrence following surgical resection of skeletal osteosarcoma.

Methods: This was a retrospective review of 102 patients who underwent surgical resection for skeletal osteosarcoma between August 2001 and August 2021. Demographics, comorbidities, tumor characteristics, treatment modalities and surgical margins were compared by univariate analysis. Multivariable analysis identified risk factors for local recurrence. Survival outcomes were estimated using Kaplan-Meier analysis.

Results: The average age of the total cohort was 25.6 ± 16.9 years and 45.1% were female. Fourteen patients (13.7%) developed local recurrence. The five-year local recurrence -free survivorship was 85.3% (95% CI [78.2%- 93.0%]) and the five-year overall survival was 70.7% (95% CI [61.6%- 81.2%]). Patients who developed local recurrence had a higher incidence of chondroblastic osteosarcoma (p< 0.01). There were no significant differences in patient demographics, chemotherapy regimen, treatment response, tumor grade, size, location or surgical margins. Multivariable analysis controlling for confounders, revealed a higher local recurrence risk for chondroblastic osteosarcoma (p< 0.05). The distribution of survival from local recurrence and overall patient survival was significantly different between groups (p < 0.001), with worse outcomes among patients with chondroblastic osteosarcoma.

Conclusion: Chondroblastic osteosarcoma was associated with an increased risk of local recurrence. Vigilant monitoring and future research on tailored management strategies are warranted to mitigate this risk or recurrence and improve patient survival in patients with chondroblastic osteosarcoma.