Prognostic factors of patients with extremity myxoid liposarcomas after surgery

BACKGROUND: Extremity myxoid liposarcoma (MLS) is a rare soft tissue sarcoma in adults. We performed this study to define distinctive clinical features of extremity MLS by assessing prognostic factors. METHODS: Between 1973 and 2015, 1756 patients with extremity MLS who underwent surgical resection were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database of the US National Cancer Institute. Both overall survival (OS) and cancer-specific survival (CSS) were assessed using the Kaplan-Meier method (to obtain OS and CSS curves) and a Cox proportional hazards regression model. RESULTS: Of the 1756 patients with extremity MLS, the mean and median patient age at diagnosis were 47 and 45 years, respectively. More than half (n = 1027, 58.5%) of the patients were male. In terms of location, 10.5% tumors were located in the upper limbs and 89.5% in lower limbs. All patients received local surgery, and about half of the patients (57.2%) received radiation treatment. The 5- and 10-year OS rates of the entire cohort were 86.4% and 75.9%, respectively. The 5- and 10-year CSS rates were 90.5% and 85.2%, respectively. On multivariate analysis, older age, male gender, high tumor grade, and tumor size > 10 cm were found to be independent risk factors of both decreased OS and CSS. Year of diagnosis ≥ year 2000 was significantly associated with an increased CSS. In addition, radiation treatment failed to become an independent risk factor for either OS or CSS. CONCLUSION: We identified age, gender, tumor grade, year of diagnosis, and tumor size as independent prognostic factors for OS and CSS in patients with extremity MLS.