Radiosensitivity translates into excellent local control in extremity myxoid liposarcoma: a comparison with other soft tissue sarcomas.

BACKGROUND: Myxoid liposarcoma has been reported to be more radiosensitive compared with other soft tissue sarcomas (STS). The authors report the results of multidisciplinary treatment of extremity myxoid liposarcoma compared with a contemporary cohort of other STS subtypes with an emphasis on the role of radiotherapy (RT) in improving local control.
METHODS: Between 1989 and 2004, 691 patients were identified from a prospective STS database who underwent combined management for localized extremity STS and were followed for a minimum of 12 months or until death. All patients underwent surgery together with pre or postoperative RT, depending on their presenting characteristics and resection margins. Demographics and outcomes were compared between patients with myxoid liposarcoma and other STS subtypes (other-STS).
RESULTS: Of 691 patients, 88 patients had myxoid liposarcoma and 603 had other STS subtypes (other-STS). Median age was 48 and 60 years for the myxoid liposarcoma and other-STS groups, respectively. Median follow-up was 86 and 61 months, respectively. For myxoid liposarcoma and other-STS groups, preoperative RT was used in 57% versus 61% of patients and postoperative RT in 43% versus 39%, respectively. The 5-year local recurrence-free survival was 97.7% for patients with myxoid liposarcoma compared with 89.6% for patients with other-STS tumors (P = .008). High-grade tumors were present in 7% and 59% of myxoid liposarcoma and other-STS patients, respectively (P = .0003). Two myxoid liposarcoma patients with local recurrence had positive resection margins, whereas only 33% of patients in the other-STS group who developed a local recurrence had positive resection margins. No patients with myxoid liposarcoma required amputation as primary management, whereas 8 (1.3%) required amputation as primary management in the other-STS group. Systemic disease control was superior in myxoid liposarcoma compared with other-STS patients, with 5-year overall and metastasis-free survival rates of 93.9% versus 76.4% (P = .0008) and 89.1% versus 66.0% (P = .0001) respectively. Of 12 myxoid liposarcoma patients with distant metastases, 7 appeared in nonpulmonary sites. In comparison, 205 (34%) patients with other-STS tumors developed systemic disease but 78% had pulmonary metastases.
CONCLUSIONS: Multidisciplinary management of extremity STS achieves high rates of local control. Myxoid liposarcoma is associated with higher rates of local control compared with other STS subtypes, after combined surgery and radiation, suggesting a particular radiosensitivity that can be exploited to improve oncologic outcome in appropriate cases.