Prognostic relevance of p53 alterations and Mib-1 proliferation index in subgroups of primary liposarcomas

For prognostic analyses of p53 alterations (p53 gene mutations + p53 immuno positivity) and Mib-1 proliferation index, we investigated 42 primary malig nant lipomatous tumors for which complete clinical data and a long follow-u p were available. p53 gene mutations were investigated by PCR-single strand conformation polymorphism-sequencing analysis, and immunohistochemistry wa s used to determine p53 protein expression and Mib-1 proliferation index, W e found a mutation frequency of 14.3%. Nine liposarcomas (21%) were p53 imm unopositive, and 11 (26.2%) had at least one p53 alteration. In myxoid lipo sarcomas, p53 alterations are not relevant to the presence or absence of ro und cell components. Pleomorphic liposarcomas showed a significantly higher proliferation index and more p53 alterations than myxoid or well-different iated variants (P < 0.001), When the Cox's regression analysis tumors of gr ade III histology (P = 0.005) was performed, the pleomorphic subtype (P = 0 .016) and liposarcomas of retroperitoneal localization (P = 0.015) showed a significantly poorer prognosis. Moreover, we found that p53 alterations an d high proliferation index correlated significantly with reduced overall su rvival. Their prognostic value seemed to be higher in myxoid than in pleomo rphic liposarcomas. The metastasis-free survival was reduced in patients wh o had liposarcomas with p53 alterations (P = 0.171) or elevated proliferati on index (P < 0.016), reflecting a more aggressive behavior. In conclusion, the determination of p53 alterations and/or Mib-1 proliferation index is u seful for assessing the prognosis of patients with liposarcomas and may esp ecially be helpful in dividing different prognostic groups for patients wit h myxoid variants.