Impact of Surgical Margins in Chest Wall Chondrosarcomas: A CanSaRCC Study

BACKGROUND: Chest wall chondrosarcoma is the most common primary malignant bone tumor of the thoracic cage. Owing to its resistance to chemotherapy and radiotherapy, complete surgical excision with negative margins remains the cornerstone of treatment. However, the optimal margin width for local control and survival remains uncertain. METHODS: Data from nine Canadian sarcoma centres participating in the CanSaRCC registry were retrospectively reviewed. Patients aged ≥ 18 years with pathologically confirmed primary chest wall chondrosarcoma (2000-2024) who underwent curative-intent resection were included. Margins were defined as the minimum measured distance from tumor to resection margin, irrespective of tissue type and categorized as positive, < 4 mm, or ≥ 4 mm. Overall survival (OS), disease-free survival (DFS), and local recurrence free survival (LRFS) were analysed using Kaplan-Meier and multivariable Cox regression. RESULTS: Among 147 patients (median age 54 years (range; 21-85), 16% had positive margins, 52% < 4 mm, and 24% ≥ 4 mm. At 5 years, OS and DFS were 77% (±4.8%) and 68% (±5.2%), respectively, for the entire cohort. Independent predictors of worse overall survival included tumor size ≥ 10 cm (HR 3.23, p = 0.021) and grade 3 tumors (HR 12.40, p < 0.001) but not margin size (margin ≥ 4 mm; HR 0.70, p = 0.512). Margins ≥ 4 mm significantly reduced local recurrence (HR 0.12, p = 0.023). CONCLUSIONS: In primary chest wall chondrosarcoma, tumor biology rather than surgical margin width drives systemic outcomes. Margins ≥ 4 mm improve local control, supporting balanced resections that preserve function while maintaining oncologic safety.