Localized Myxoid/Round Cell Liposarcoma In Adult Patients. Il6 Protein Expression Analysis

10075 Background: Myxoid/round cell liposarcoma (MLPS) is an uncommon soft tissue sarcoma with a relatively favorable prognosis and is considered a low grade malignancy. Methods: Retrospective analysis of 123 localized MLPS adult patients (pts) treated at our institution from 1987 to 2005 was performed. Paraffin embedded tissue was analyzed for IL6, IL6 receptor, NFkB and bcl-2 protein expression (positive (+) or negative) by tissue microarray immunostaining. Results: The median age of the 77 males and 46 females was 42 years (yr) (range 15–70). Lower extremity (LE) was the site more affected (77 pts). Median tumor size was 11 cm (range 2.5–40 cm), 87 were deep tumors and 63 were grade 1 tumors. Preoperative biopsy was carried on 38 pts. All but 2 pts underwent surgery (R0 24%, R1/R2 76%); 44 pts had a second surgery. Chemotherapy (CT) and radiation therapy were given to 30% and 52% of pts respectively. Complete remission was achieved in 98% of pts. After a median follow up of 6 yr (range 0.1–19 yr) 53 pts relapsed (43%); 37 locally, 11 distant and 5 both. Metastases occurred in 26 pts, 17 solitary and 9 multiple. The 5-yr, 10-yr and 15-yr DFS were 56%, 48% and 44% respectively. Median time to first relapse was 6.5 yr (range 0.1–16 yr). The 5-yr, 10-yr and 15-yr OS are 90%, 79% and 64% respectively. Tumor site, pre-surgical biopsy, R0 surgery and second surgery correlates with a better DFS in the multivariate analysis. So far 19 tumors have been studied for, NFkB (+) 57%, IL6 (+) 47% and Bcl2 (+) 30%, positivity. All tumors (+) for IL6 were also (+) for IL6 receptor. None of the proteins correlated to DFS and/or OS. Conclusions: Pts with localized resected MLPS require a prolonged follow-up since relapses occur after 10 yrs. PFS and OS correlate with an optimal loco-regional treatment. Half of MLPS expressed IL6, probably involving an autocrine phenomenon; whether this cytokine is involved in tumor aggressiveness, remains to be established. No significant financial relationships to disclose.