(P 161) CLINICAL CHARACTERISTICS, PATTERNS OF CARE, AND TREATMENT OUTCOMES OF CHONDROSARCOMA: A SINGLE-INSTITUTIONAL EXPERIENCE

Objective: Chondrosarcomas (CS) represent a spectrum of malignant connective tissue tumors whose management remains uncertain, with high-grade patients experiencing particularly poor outcomes.

Methods: We retrospectively reviewed CS patients evaluated at The Ohio State University between January 1, 2010 to March 7, 2022. Demographics, histologic subtypes, tumor characteristics, treatments, and survival outcomes were analyzed.

Results: Of 140 patients identified, 118 were evaluable with adequate follow-up. 91.5% were white and 50.8% were male. Median age at diagnosis was 57 (range: 21-84).

70.3% had Conventional CS, 13.5% Dedifferentiated CS, 3.4% Mesenchymal/Clear cell CS, and 12.7% Myxoid/Extraskeletal myxoid CS. At diagnosis, 47.5% had Grade I tumor, 29.7% Grade II tumor, and 18.6% Grade III tumor. 92.2% had localized disease at presentation and the median primary tumor size was 6.3 cm. The lower extremities were the most common primary site (36.4%), followed by thoracoabdominal (38.9%), skull base/head and neck (14.4%), and upper extremities (10.2%).

94.9% of patients received surgery, of whom R0 margins were achieved in 70.5%, R1 margins 17.0%, and R2 margins 0.1%, with the remainder undefined. 15.3% of patients (of whom 22.2% had localized disease and 77.8% metastatic disease) received systemic therapy, most frequently Pazopanib (55%). 10.2% of patients received radiation therapy, 41.7% with palliative intent and 58.3% with locally definitive intent.

Median overall survival in the entire cohort was 90.6 months. The median survival time differed significantly by subtype: Conventional CS 104.6 months, Dedifferentiated CS 25.9 months, Mesenchymal/Clear cell CS 57.2 months, Myxoid/Extraskeletal myxoid CS 108.3 months (Chi-square p< 0.001). No association was seen between anatomic subsite and overall survival (upper extremities 202.80 months, lower extremities 85.30 months, and Pelvis/Retroperitoneal/Lower back & Chest/Abdomen Wall/Upper Back 82.3 months, p=0.216). Grade was associated with overall survival: Grade I median 202.80 months, Grade II 80.87 months, and Grade III 21.067 months (p=0.000).

Conclusion: CS remains a clinical challenge due to its rarity and limited treatment options. While surgical resection remains the primary treatment for localized disease, systemic therapy and radiation can have important roles in patients with locally recurrent, advanced, or metastatic disease. These findings highlight the need for subtype-specific strategies and prospective trials to refine CS care.