(P 125) CHARACTERISTICS, MANAGEMENT AND SURVIVAL OF N=7314 LIPOSARCOMAS FROM THE NATIONWIDE NETSARC REGISTRY IN FRANCE SINCE 2010

Objective: Liposarcomas are among the most common sarcomas, but gather a diversity of rare to ultrarare molecular subtypes whoses natural history and presentation is not always described. We report the analysis of the different liposarcoma subtypes in the nationwide NETSARC

Methods: NETSARC (netsarc.org) is a network of 26 reference sarcoma centers with specialized multidisciplinary tumor boards (MDTB), funded by the French INCA since 2010. Its aims are to improve the quality of diagnosis and care of sarcoma patients. Patients’ characteristics, treatments and outcomes are collected in a nationwide database. The objective of this analysis was describe and present the outcome of all liposarcomas confirmed by central review pathology review and integrated between 2010 and 2023 in the NETSARC+ database.

Results: 7314 liposarcomas are included in the database for an overall incidence of 8.3/106/y. Median age wads 65 (Q1-Q3 : 53-74, range 0-97 y), with 4479 males (61.2%), with 3666 (50.1%) dediff. (DDLPS), 1531 (20.9%) well diff. LPS (WDLPS), 1124 (15.4%) myxoid LPS (MLPS), 401 (5.5%) Pleomorphic LPS (PLPS), 149 (2.0%) Round cell LPS (RCLPS), 12 (0.2%) myxoid pleomorphic LPS, (MPLPS) 18 (0.2%) mixed type (MTLPS) LPS, and 413 (5.6%) unclassified LPS (ULPS).
Primary tissues were soft tissue (6874, 94%), visceral (414, 5.7%), bone (26, 0.4%).
Primary anatomic sites were internal trunk (3806,52.0%), lower limb (1878, 25,7%), trunk wall (772, 10.5%), upper limb (256, 3.5%), Head and neck (155,2.1%), GI (120, 1.6%), Gyne (17,0.2%), other 303, 4.0%).
Age of diagnosis were different: MPLPS MLPS & RCLPS occurred at a younger age (median 47-49) vs WD/DD/PLPS/MTLPS occurred at a median age of 64 to 67.
The different histotypes had different presentations.
WD& DDLPS had similar sites, with >2/3 from the internal trunk and 15% from the limbs. DDLPS occurred 3 years earlier (p< 0.0001), more frequently in men (64% vs 59% p< 0.00001), with more M+ patients in DDLPS (9% vs 2%, p< 0.001), suggesting a dedifferentiation process between the 2 diseases occurring more often in men. PLPS shared similar age, gender size, M+ rates with DDLPS.
In MLPS and RCLPS, primary sites, gender, size, M+ at diagnosis were similar.
Myxoid pleomorphic LPS was the only histotype more frequent in women (p< 0.001), with 59% trunk and 41% limb sites respectively.
Management of patients in reference centers were observed less often for DDLPS and pleomorphic LPS, with a worse compliance to CPGs (p< 0.0001).
The overall survival of DDLPS was significantly worse than that of all other subtypes MLPS (HR: 0.26 [0.21-0.33]), PLPS (HR: 0.76 [0.59-0.98]), RCLPS (HR:0.30 [0.18-0.50]), WDLPS (HR: 0.30 [0.24-0.37]), unclassified LPS (HR: 0.53 [0.37-0.75]).

Conclusion: In this large nationwide series of all pathology confirmed LPS diagnosed in France over 13 years, the clinical presentation, management and survival of histotypes are very different. DDLPS may evolve from WDLPS more often in men. DDLPS remain the subtype with the worse prognosis.