(P 149) SURGICAL TEXTBOOK OUTCOMES IN PATIENTS DIAGNOSED WITH CHONDROSARCOMA

Objective: To characterise clinicopathological features, surgical treatment patterns, and survival outcomes in patients(pts) diagnosed with chondrosarcoma(ChS), and to determine complications following primary ChS resection.

Methods: We retrospectively analysed ChS pts treated at reference centre over the last 25 years. Median relapse-free survival (mRFS) and median overall survival (mOS) were analysed. We used the Kaplan-Meier to calculate the median values of relapse-free survival (mRFS) and overall survival (mOS); the log-rank test was used to assess potential prognostic factors; and Clavien-Dindo scale - to classify surgical complications.

Results: 205 ChS pts were included (median age: 51.84 years; 114 male (55.6%), 91 female (44.4%)). Histological subtypes included: conventional (CChS; n=134, 65.4%), secondary peripheral (SChS; n=25, 12.2%), dedifferentiated (DDChS; n=21, 10.2%), mesenchymal (MCS; n=12, 5.9%). The histologic grades were: G1 (n=83, 40.5%), G2 (n=65, 31.7%), G3 (n=38, 18.5%) and Gx (n=13, 6.3%). R0 resection was achieved in 132 pts (64.4%), R1 in 45 pts (22%) and R2 in 19 pts (9.3%). Amputation was performed in 22 cases (10.7%) - mostly due to primary tumour volume (21/22). 110 pts (53.7%) underwent resection with reconstruction, while endoprosthesis was used in 57 pts (27.8%) and curettage in 13 pts (6.3%). Hemipelvectomy was performed in 37 pts (18%) and the Tikhoff–Lindberg procedure in 38 pts (18.5%). The entire cohort demonstrated mRFS of 41.8 months(mo; 5-year: 45.2%), and mOS of 103.6 mo (5-year: 65.2%). Both values were significantly associated with histological grade (log-rank p< 0.001), with G3 and Gx subtypes demonstrating markedly poorer outcomes. No surgical complications were observed in 84 pts (41%), Grade II occurred in 58 pts (28.3%), IIIB in 27 pts (13.2%), and I in 26 pts (12.7%). A single grade V fatal event (n=1; 0.5%) was recorded.

Conclusion: ChS represents a high heterogeneity. Histopathological diagnosis, including grade significantly influences patients outcomes. Surgical complications have to be considered in clinical decision-making. These data reinforce the importance of referral to high-volume sarcoma centres capable of achieving wide margins and complex reconstructions.