(P 162) CHONDROSARCOMA OUTCOMES IN YOUNG VERSUS ADULT POPULATIONS

Objective: Chondrosarcoma is rare in patients under 25 years of age. While outcomes of chondrosarcoma in adults have been explored, there is limited data comparing outcomes between patients based on age. Thus, the purpose of this study was to compare presentation and outcomes of chondrosarcoma in patients older and younger than age 25.

Methods: We retrospectively reviewed all patients who were diagnosed with musculoskeletal chondrosarcoma at one institution from 1990-2022. Patients were grouped into cohorts based on age greater than 25 years (N=285) or less than 25 years (N=26) at the time of chondrosarcoma diagnosis. Average age at time of surgery was 19 years (range, 12-25) for the young group, and 55 years (range, 26-88) for the adult group. Average follow up was 10±7 years in the young group, and 6±15 years in the adult group (p=0.2)

Results: There were no differences in rates of neoadjuvant and adjuvant chemotherapy or radiation between groups (p>0.7). Eighteen (70%) patients presented with soft tissue masses in the young group compared to 190 (67%) in the adult group (p=1). At presentation, 3 (12%) patients in the young group had pathologic fractures compared to 44 (15%) patients in the adult group (p=0.8). There were no patients in the young group with metastatic disease at presentation, compared to 5 (2%) patients in the adult group (p=1). Adults had higher rates of dedifferentiated chondrosarcoma at diagnosis (p=0.03), while the young cohort had higher rates of low-grade disease (p=0.005). There was no difference in local recurrence-free survival (LRFS) between groups (p=0.4), with a 10-year local recurrence-free survival of 87% in the young cohort and 79% in the adult cohort. There were no differences in metastatic disease-free survival (MDFS), with rates of 96% at all timepoints in the young cohort compared to 82%, 79%, and 78% in the adult cohort at 2-, 5-, and 10-years (p=0.05). Grade adjusted disease-specific survival (DSS) at 2-, 5-, and 10-years was 95%, 95%, and 89% in the young cohort compared to 79%, 70%, and 62% in the adult cohort (p=0.5).

Conclusion: Young patients with chondrosarcoma demonstrated similar characteristics on presentation and treatment modalities as adults. LRFS was similar in young and adult patients, with MDFS and DSS trending toward improved survival in the young cohort.