The cyclin dependent kinase inhibitor p27 and its prognostic role in breast cancer

p27 is an inhibitor of cyclin dependent kinase involved in the regulation of the cell cycle. In this commentary we discuss the current knowledge on p27 in breast cancer and its significance in predicting the outcome. p27 protein levels are high in most cases of breast carcinomas, are correlated with the levels of cyclin D1 and estrogen receptor, and could be a useful predictor of survival, because they are low in aggressive carcinomas. Immunodetection of p27 in breast tumors could be useful in the assessment of prognosis, especially in those cases in which the commonly used parameters are insufficient, and might ultimately influence the therapy of this disease.