Myxoid/round cell and pleomorphic liposarcomas: prognostic factors and survival in a series of patients treated at a single institution.

Background: 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 rates 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.