p27(kip)₁ protein expression correlates with survival in myxoid and round-cell liposarcoma

Purpose: The p27(kip1) protein (p27) is a cyclin-dependent kinase inhibitor that has been shown to be an independent prognostic factor in a variety of human neoplasms. Low expression of p27 tends to occur in more aggresive neoplasms. The role of p27 as an independent prognostic factor in the spectrum of myxoid and round-cell liposarcomas has not been examined. Materials and Methods: Forty-seven cases of myxoid and round-cell liposarcomas were examined. Clinicopathologic features and immunohistochemical expression of p27 and Ki-67 antigen were studied in all cases. Survival analysis was performed using the log-rank test and the Cox multivariate regression model. Results: The male:female ratio was 1.4:1, and the mean age at diagnosis was 45 years. The tumors were located in the lower extremities (94%) and retroperitoneum (6%). The median tumor size was 13.5 cm. The median follow-up was 6.3 years, and the overall 5- and 10-year survival rates were 76% and 67%, respectively. Low expression of p27 was identified in 34 cases (72%) and correlated with decreased metastasis-free (P = .026) and overall survival (P = .008). In a multi-variate analysis, only round-cell differentiation and low expression of p27 independently predicted decreased metastasis-free and overall survival. Conclusion: p27 expression predicts the clinical behavior of myxoid and round-cell liposarcomas, even in neoplasms with few or no round-cell differentiation. (C) 2000 by American Society of Clinical Oncology.