Is multimodality therapy necessary for the management of pure myxoid liposarcomas? A multi-institutional series of pure myxoid liposarcomas of the extremities and torso

Background and Objectives: The treatment of patients with pure (<5% round cell component) myxoid liposarcomas (pMLS) has not been well characterized. We hypothesized that multimodality therapy (oncological resection with radiation therapy) may not be necessary for pMLS. Methods: Patients who underwent resection of localized pMLS at three institutions from 2000 to 2010 were identified and treatment variables were analyzed. Results: Of 75pts with pMLS, the median tumor size was 10 cm, the majority (95%) were deep tumors, and located in lower extremity. Radiation (XRT) was administered to 58pts(77%). Comparing the no XRT to XRT patients, lower extremity location (77% vs. 79%, P = 1.0), tumor size (13 vs. 11 cm, P = 0.3), and positive margins (13% vs. 16%, P = 1.0) were similar. The majority (82%) of patients not receiving XRT had deep tumors. After a median follow-up of 60 months, 2pts (3%) developed local recurrence and 10pts (13%) developed distant recurrence with a mean recurrence-free survival (RFS) and disease-specific survival (DSS) of 114 and 148mos, respectively. In multivariate analyses, increasing age and tumor size were the only significant predictors of recurrence. XRT was not a significant predictor of RFS in multivariate analysis. Conclusions: pMLS is an STS subtype with favorable tumor biology and an extremely low-rate of local recurrence. Our results suggest that multimodality therapy may not be necessary for all pMLS.