p27(kip1) 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 aggressive n eoplasms. The role of p27 as an independent prognostic factor in the spectr um of myxoid and round-cell liposarcomas has not been examined. Materials and Methods: Forty-seven cases of myxoid and round-cell liposarco mas were examined. Clinicopathologic features and immunohistochemical expre ssion 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 retro peritoneum (6%). The median tumor sire war 13.5 cm. The median follow-up wa s 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 multivariate 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 rou nd-cell liposarcomas, even in neoplasms with few or no round-cell different iation. J Clin Oncol 18:2888-2893. (C) 2000 by American Society of Clinical Oncology.