AbstractBACKGROUND.The objective of this study was to investigate prognostic factors and clinical outcome of myxoid/round cell and pleomorphic liposarcoma.METHODS.Three hundred twenty‐nine patients with localized myxoid/round cell or pleomorphic liposarcoma who underwent surgery at the Istituto Nazionale per lo Studio e la Cura dei Tumori (Milan, Italy) over 25 years were reviewed. The reates of local recurrence, distant metastases, and survival were studied.RESULTS.Two hundred fourteen patients presented with primary disease, and 115 patients had locally recurrent tumors. The disease‐specific survival rate was 75% at 10 years, and the local recurrence and distant metastases incidence were 25% and 15%, respectively. Presentation with recurrent disease, tumor size (>10 cm), tumor grade (French Federation of Cancer Centers grade II or III vs grade I), and positive surgical margins were independent predictors of death. Tumor site and radiation therapy also played a role, mostly related to their effect on local outcome. Pathologic grade and histologic subtype influenced distant metastases. Extrapulmonary metastases were associated with poorer postmetastatic disease‐specific survival.CONCLUSIONS.Myxoid/round cell liposarcomas shared similar prognostic factors with other soft tissue sarcomas and had a relatively good clinical outcome. The presence of >5% of round cell component singled out a group of patients at greater risk of metastases and death but with a broad spectrum of disease aggressiveness. Extrapulmonary metastases were a peculiar pattern of myxoid/round cell liposarcoma that require special consideration for treatment and prognosis. Cancer 2007. © 2007 American Cancer Society.