(P 150) LOCAL RECURRENCE OF CHONDROSARCOMA: IMPACT ON SURVIVAL AND RECURRENCE AT AN INCREASED GRADE

Objective: Chondrosarcoma grade has been established as a predictor of disease-specific survival (DSS). Impact of local recurrence (LR) on DSS, however, remains controversial. Increased tumor grade following LR has been reported in 10% of LRs, however no studies have compared outcomes based on increased grade. The aim of this study was to evaluate the impact of LR on DSS and report outcomes of chondrosarcoma that recur at an increased grade.

Methods: Three-hundred-and-nine patients with surgically treated chondrosarcoma between 1989 and 2022 were retrospectively reviewed. Demographic and treatment characteristics were collected, local recurrence free survival (LRFS) was calculated, and DSS was compared between those that recurred at a similar grade versus an increased grade.

Results: LRFS was 80% at 10 years. LR was associated with disease-specific mortality based on time-dependent binary covariate analysis (HR 9.38, 95% CI [5.40, 16.3], p < 0.001). Of those that recurred, 33 had pathology available (Table 1) for review. Recurrence occurred at an increased grade in 10 (30%), decreased grade in 1 (3%), and same grade in 22 (67%). Increased grade changes included: Grade 1 to 2 (n=2); Grade 1 to 4 (n=1); Grade 2 to 3 (n=3); Grade 2 to 4 (n=4). Ten-year DSS did not differ between groups based on similar or increased grade LR (68% vs. 21%, p=0.3).

Conclusion: LRFS in this cohort was 80% at 10 years, with LR a risk factor for worse DSS. Increased grade occurred in 30% of LR, three times higher than published in previous series. While no survival differences can be elucidated for increased LR in this study, increased grade trended toward worse DSS.

Table 1: Demographic and tumor features of patients with recurrent chondrosarcoma