1749P - Vertebral MRI in the screening for bone metastasis in myxoid liposarcoma: Is it justified?

Background

Myxoid round cells liposarcoma (MLPS) is a rare type of sarcoma with distinct clinical and molecular features. In advanced setting, with a particular predilection for bone metastasis (BM), a vertebral MRI as a screening test is recommended (especially with round cells (RC)). In this study, we evaluate the performance of vertebral MRI in clinical practice, emphasizing the characteristics of BM and pts survival.

Methods

This is a retrospective analysis of MLPS pts with BM treated at Gustave Roussy between January 1990 and March 2024 from the MLPS cohort (MLPS-GR). The demographic and clinical features were retrieved from the electronic records and their survival data. In addition, data on vertebral MRI were also assessed.

Results

Among 336 pts, 22 had BM (6.5%) of whom 5 at diagnosis (22.7%). They constitute around 20.2% of metastatic sites among 109 with advanced disease. 31 of 336 (9.2%) had a screening vertebral MRI. Of 31 pts, 3 had BMs (9.7%, 1 had RC) of whom 2 had bone-only disease thus serving the purpose of screening. Among those without detectable RC (18 out of 31), only one had BM. In MLPS with BM (22 pts), there were 19 males (86.4%) and a median age of 39.5 yrs. The most common primary site was in lower arms (90.9%) while 12 (66.6%) had grade 1, and 6 had grade 2 (33.3%). 14 had more than 5 bone sites (63.6%). Out of 14, 8 had detectable RCs (57.1%). 16 had an MRI for detecting metastasis (72.7%) and 6 had a CT scan (27.3%). 14 had a bone complication (63.6%): medullary compression (35.8%) and epiduritis (64.2%). All received radiation therapy except 1 having surgery. Median time to BM was 30.4 mo with a max. of 193.7 mo, of whom 2 had a time to BM≤ 6 mo (2.7 and 5.4 mo) that could be considered missed cases since no MRI was done. Median OS was 28.1 mo (15; NR). At 6 mo, the OS was 86.1% [72.7;100] while at 1 and 5 yrs, it reached 86.1% [72.7;100] and 43.2% [23.4;79.6].

Conclusions

Bone is a rare site of metastatic disease in MLPS (6.5%) with a median survival beyond 2 yrs. Vertebral MRI is commonly performed to detect BMs and optimize treatment strategies. Our data shows that despite bone-only disease at diagnosis of MLPS is rare, MRI should still be considered, especially in high-risk pts. Larger trials should be conducted to decipher better the subgroup of pts who benefit most from this approach.

Clinical trial identification

Editorial acknowledgement

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.