1751P - Clinical and survival data of 336 myxoid liposarcoma patients: The Gustave Roussy experience

Background

Myxoid liposarcoma (MLPS) constitutes around 15% of all liposarcoma. They are characterized by a specific translocation, the t(12;16), leading to the fusion of FUS to DDIT3, which confers specific molecular features. In this study, we assessed the clinical and survival data of MLPS pts (patients) with evaluation of the impact of various clinical and tumor features on survival outcomes.

Methods

This retrospective study included MLPS pts treated at Gustave Roussy between January 1990 and March 2024. All clinical features were gathered as well as survival data and management details. In addition, we performed univariate (UVA) and multivariate analyses (MVA) to evaluate the impact of various factors on survival (age, gender, adjuvant chemotherapy (CT) and radiation therapy (RT), primary site, and tumor grade (TG)).

Results

336 pts were included (median age of 43 yrs and 60.4% were men). They occurred in the lower arms (75.3%, 253 pts, most in the hip (73.1%)), followed by the trunk (9.8%, 33 pts). TG 1 tumor was in 172 pts (64.7%), TG 2 in 85 (31.9%), and TG 3 in 9 (3.4%). 311 pts had surgery (93.9%) of whom 165 had adjuvant RT (53.1%) while 78 received peri-operative CT (25.1%). Out of 317 pts, 85 had at least one local relapse (LR) (26.8%) with a median time to LR of 24.3 mo. At 6 mo, the LR-free survival (LR-FS) was 96% while the 1- and 5-year LRFS reached 92.2% and 75.8%. 95 had at least one metastatic relapse (MR) (30.3%) with a median time of 38.3 mo. [25.9;45.7]. At 6 mo., the MRFS was 98% while the 1- and 5-year reached 94.8% and 70.6%. The median OS was not reached (NR) [249; NR]. At 6 mo., the OS was 98.8% while the 1- and 5-year were 97.7% and 89.3%. In the UVA, adjuvant RT (p<0.001) and CT (p=0.008) had an impact on LR while in the MVA, adjuvant RT (p<0.001) and age (p=0.03) were significant. Male gender (p=0.01) and high TG (p=0.02) had a higher risk of MR as well as shorter survival (male gender (p=0.04) and TG (p=0.004)).

Conclusions

In one of the largest retrospective cohorts, 336 MLPS pts were commonly diagnosed with a tumor in the lower arms with a localized setting. It is characterized by a high risk of both local (26.8%) and distant relapse (30.3%) but with prolonged survival. Male gender and a higher tumor grade were associated with an increased risk of distant relapse and shorter survival.

Clinical trial identification

Editorial acknowledgement

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.