P27(Kip1) expression in breast carcinomas: An immunohistochemical study on512 patients with long-term follow-up

p27(Kip1) (p27), a cyclin-dependent kinase inhibitor, has an important role in the progression of cells from G(1) into S phase of the cell cycle. p27 may act as a tumor suppressor, and several reports suggest that; loss of it s expression in breast carcinoma is related to tumor progression and poor p rognosis. We evaluated p27 immunohistochemical expression in 512 consecutiv e cases of breast carcinoma with 9 years of median-term follow-up. p27 expr ession was heterogeneous and frequently less intense than in normal cells. Low p27 expression (<50% of reacting cells) was associated with grade III t umors, N0 status, estrogen receptor-negative status, and low cyclin DI expr ession. In the whole series of cases, p27 expression did not predict outcom e. In node-negative cases (249 patients), high p27 expression indicated poo r prognosis. p27 was not prognostically relevant in the group of 223 patien ts with pTI disease or in the group of 154 patients <50 years of age. We al so investigated the prognostic value of the combined expression of p27 and cyclin DI, but no differences in survival were seen in this bivariate analy sis. (C) 2000 Wiley-Liss, Inc.