[63] Dedifferentiated Liposarcoma Is the Most Frequent Liposarcoma Subtype. A Study from the French Sarcoma Group on the Subtype Frequencies in a Series of 1384 Liposarcomas with a Systematic Molecular Characterisation

Agnes Neuville, Anne-Valerie Decouvelaere, Philippe Terrier, Frederique Larousserie, Bruno Chetaille, Sophie Le Guellec, Yves-Marie Robin, Celine Charon-Barra, Dominique Ranchere-Vince, Jean-Michel Coindre. Institut Bergonié, Bordeaux, France; Centre Léon Bérard, Lyon, France; Institut Gustave Roussy, Villejuif, France; Hôpital Cochin, Paris, France; Institut Paoli Calmette, Marseille, France; Institut Claudius Regaud, Toulouse, France; Centre Oscar Lambret, Lille, France; Centre Georges-François Leclerc, Dijon, France

Background: The standards for subtyping liposarcomas (LPS), and particularly for identifying dedifferentiated LPS, have recently changed with the more and more frequently use of molecular analysis. Therefore, the exact frequency of LPS subtypes is unknown.
Design: A national network of pathologists has been set up in France for a systematic review of every new sarcoma. Moreover, a molecular test is systematically performed for every suspicion of translocation (FISH or RT-PCR), MDM2 amplification (FISH, Q-PCR or array-CGH) or specific mutation. The following data are collected in a shared database (http://www.rreps.sarcomabcb.org): sex, age, location, depth and size of tumor, date and type of sampling, type and result of molecular test and histotype.
Results: From January 1st 2010 to June 30th 2012, 5665 soft tissue sarcomas were collected with 1388 LPS (24%) with 562 (40%) dedifferentiated LPS (DD-LPS), 545 (39%) atypical lipomatous tumors/well differentiated LPS (ALT/WD-LPS), 205 (15%) myxoid/round cell LPS (MR-LPS), 62 (5%) pleomorphic LPS (P-LPS) and 14 (1%) NOS-LPS. In the category of ALT/WD, DD, and MR-LPS, molecular analysis was positive in 1222 cases (93%), negative in 3 cases (MR-LPS) non contributive in 35 cases (2.7%) and not done in 52 cases (4%). Sex, age and location according to histotype is shown in the Table 1

Table 1: Sex, age and location according to LPS subtypes
Type of LPSALT/WD-LPSDD-LPDMR-LPSP-LPS
Sex (M/F)1.151.81.52.1
Median age (years)65704665
Limbs (n*)2537216730
Internal trunk (RP**)170 (120)425 (312)9 (0)11 (7)
Trunk wall108522920
Head and Neck141301
n*: number of cases; RP**: retroperitoneum


Conclusions: In this prospective systematic review of sarcomas, DD-LPS and ALT/WD-LPS represent almost 80% whereas MR-LPS represent only 15% of all LPS. With a more systematic molecular analysis, DD-LPS is actually more frequent than previously thought.
Category: Bone & Soft Tissue

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 24, Tuesday Afternoon

 

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