Résumé
Background Liposarcomas (LPS) are among the most common sarcomas, but gather a diversity of rare to ultrarare molecular subtypes whose presentations and natural histories are partially characterized. The aim of the work was to describe the presentation and outcome of the different LPS histotypes from the NETSARC+ registry. 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 aiming to improve the quality of care of sarcoma patients. Patients' characteristics, treatment and outcomes are collected in a nationwide database. This work describes the outcome of all LPS confirmed by central review pathology review and integrated between 2010 and 2023 in the NETSARC+ database. Findings 11,132 liposarcomas are included in the database for an estimated incidence of 11.5/10 6 /y. Median age was 65 (Q1-Q3: 53-74, range 0-97 y), with 6529 males (58.7%), with 4220 (37.9%) dedifferentiated (DDLPS), 1838 (16.5%) well differentiated LPS (WDLPS) & 2424 (21.8%) atypical lipomatous tumours (ALT), 1371 (12.3%) myxoid LPS (MyxLPS), 450 (4.0%) pleomorphic LPS (PLPS), 177 (1.6%) high grade myxoid LPS (HGMLPS), 24 (0.2%) mixed type liposarcomas (MTLPS), 14 (0.1%) myxoid pleomorphic LPS (MPLPS) and 614 (5.5%) non classified LPS (NCLPS). Age, sex and sites differed across histotypes, but overall, all histotypes were represent in all age groups and sites. We report first on a difference in the sex ratio of liposarcoma in different age groups. Women were less frequently affected with liposarcomas after 50, in DDLPS, MyxLPS and HGMLPS. The median overall survival of DDLPS was 144 months, significantly worse than that of MyxLPS (HR: 0.26 [95% CI 0.21–0.33]), PLPS (HR: 0.76 [95% CI 0.59–0.98]), HGMLPS (HR: 0.30 [95% CI 0.18–0.50]), WDLPS (HR: 0.30 [95% CI 0.24–0.37]), unclassified LPS (HR: 0.53 [95% CI 0.37–0.75]). In addition to a lower incidence, women aged >50 had a better relapse free and overall survival than male, while this was not observed in the group aged 50 or under. In multivariate analyses, size and age were independent prognostic factors for the most common subgroups, but specific prognostic parameters were observed in each molecular subgroup. Female >50 was an independent favorable prognostic factor for the largest groups of DDLPS. Interpretation In this nationwide series of pathology-confirmed LPS, the clinical presentation, management and survival of histotypes are very different with age-related sex differences favoring women >50. DDLPS is the subtype with the worse prognosis